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Perceived Loss of Memory Ability and Cerebral Metabolic Decline in Persons With the Apolipoprotein E-IV Genetic Risk for Alzheimer Disease
Linda Ercoli, PhD;
Prabha Siddarth, PhD;
Sung-Cheng Huang, PhD;
Karen Miller, PhD;
Susan Y. Bookheimer, PhD;
Benjamin C. Wright, MD;
Michael E. Phelps, PhD;
Gary Small, MD
Arch Gen Psychiatry. 2006;63:442-448.
ABSTRACT
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Context Concerns about age-related memory loss are greater in persons who have the apolipoprotein E-IV (APOE4) genetic risk for Alzheimer disease, but the correlation between the degree of concerns and future cerebral metabolic decline is unknown.
Objective To investigate whether the degree of self-perceived memory loss is associated with regional cerebral metabolic decline.
Design Longitudinal study.
Setting Aging and Memory Research Center, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles.
Participants Thirty right-handed, cognitively intact, middle-aged and older adults (age range, 50-82 years) with age-associated memory complaints, 14 of whom were carriers of the apolipoprotein E-IV allele, were recruited for longitudinal study.
Main Outcome Measures At baseline, we administered a standardized neuropsychological battery and assessed self-appraisal of memory functioning using the Memory Functioning Questionnaire, which yields 4 factor scores indicating frequency of forgetting, seriousness of forgetting, retrospective functioning, and mnemonics use. Regional cerebral glucose metabolism was determined using fluorodeoxyglucose F18–positron emission tomography at baseline and after 2 years.
Results At baseline, APOE4 carriers and noncarriers did not differ significantly on objective memory measures or on Memory Functioning Questionnaire factor scores. However, the factor score for frequency of forgetting significantly correlated with global cerebral metabolic decline in all subjects regardless of APOE4 genetic risk (P = .01). By contrast, the factor score for mnemonics use significantly correlated with metabolic decline in the temporal regions in APOE4 carriers but not in noncarriers (P = .03).
Conclusions The degree of perceived memory loss correlates with subsequent global cerebral metabolic decline for APOE4 carriers and noncarriers; hence, memory complaints may reflect underlying cerebral metabolic changes. Compensatory strategies, as reflected by more frequent mnemonics use in APOE4 carriers, may reflect underlying metabolic changes in the brain regions associated with prodromal Alzheimer disease. Self-reported mnemonics use may be helpful in identifying persons for clinical monitoring.
INTRODUCTION
Memory complaints are common in middle-aged and older adults. In community-based studies, the prevalence of subjective memory complaints ranges from 22%1-2 to 56%,3 but rates may vary depending on the type of surveying, the affective status, and the demographics or composition of the sample.4
Memory complaints of patients are often brought to the attention of a physician, but whether increasing complaints signal future objective cognitive decline or dementia is controversial. Although the results of some longitudinal studies5-11 indicate that memory complaints are associated with future cognitive decline or dementia, the results of other studies3, 12-17 do not. Discrepancies can be attributed to methodological factors, study design, and control of variables commonly associated with cognitive complaints or cognitive decline, such as age, education, and depression.3-4,7 Baseline cognitive functioning,5-7,16 psychological distress,15 physical deficits,3 and recency of onset of subjective memory complaints5 correlate with cognitive decline, sometimes more so than subjective memory complaints. The relationship between subjective memory complaints and change in cognition may vary as a function of ethnicity.3 The predictive validity of subjective memory complaints may depend on the sensitivity of objective tests16 and on the extent to which objective tests measure the types of everyday difficulties assessed by subjective memory complaint measures.18
Physiological indexes of brain function or biological (genetic) markers for dementia risk offer an alternative approach to assessing the predictive validity of memory complaints. Few investigations have addressed the association between memory complaints and underlying brain function, but in one such study19 the patterns of cerebral activation during functional magnetic resonance (MR) imaging distinguished between diagnostic groups with subjective memory complaints. An association between subjective reports of increased use of memory aids and resting-state frontal lobe glucose metabolism in nondemented older adults has been found.20-21
One biological marker of dementia that may be useful in assessing the predictive validity of memory complaints is the apolipoprotein E-IV (APOE4) allele. Possession of APOE4 is a major risk factor for sporadic and familial late-onset22 and early-onset23 Alzheimer disease (AD). APOE has 3 allelic variants (variants 2, 3, and 4) and 5 common genotypes (genotypes 2/2, 2/3, 3/3, 3/4, and 4/4). Possession of APOE4 confers increased risk for AD in a dose-related fashion,24 while possession of APOE2 confers protection.25
Several investigations have identified a relationship between APOE4 genetic risk and cognitive complaints with respect to family history of AD,26 depression,27-28 and cognition.29-30 Findings from a previous study28 suggest that memory complaints in APOE4 carriers may reflect underlying neurobiological determinants.
To our knowledge, no previous study has examined whether the degree of subjective memory complaints among nondemented persons with memory complaints is associated with future brain metabolic decline according to APOE4 genetic risk. We investigated whether the degree of subjective memory complaint, as measured by Memory Functioning Questionnaire (MFQ) factor scores,31 APOE4 genetic risk, and their interaction, were associated with regional cerebral metabolic decline in 30 nondemented persons who were followed up longitudinally.
METHODS
SUBJECTS
The 30 subjects were drawn from a larger longitudinal study32 of predictors of cognitive decline. Subjects were recruited irrespective of family history of AD and memory complaints. To increase the likelihood of obtaining APOE4 carriers, some advertisements and physician referrals emphasized middle-aged and older persons with memory complaints and family histories of dementia in a first-degree relative. Subjects received neurological and psychiatric evaluations and routine screening laboratory tests to rule out treatable causes of cognitive impairment or potential cognitive confounding factors (eg, severe sensory deficits or nonpsychotropic medication interactions). All subjects were proficient in the English language. A neuropsychological battery was administered to quantify cognitive performance and to confirm the absence of a diagnosis of dementia or mild cognitive impairment.33-34 The 17-item Hamilton Rating Scale for Depression35 was administered to assess mood.
Of 573 volunteers, we excluded 520 for various reasons (eg, medication use, concurrent use of psychotropic medications, concurrent medical or psychiatric illness, dementia or mild cognitive impairment, unclear or ambiguous family history of dementia, and presence of a neurological, medical, or major psychiatric condition that could affect memory or cognitive processing). Of the remaining 53 subjects, 35 returned for follow-up, but only 30 subjects had complete MFQ data. The other subjects did not return for follow-up for several reasons (eg, they were lost to follow-up, declined participation, developed exclusionary medical conditions, or started exclusionary medications).
We conducted an attrition analysis to determine if the 30 subjects who completed the study differed on demographic variables or on cognitive test results from the 23 subjects who did not complete the study. We found that the 2 groups did not differ significantly in age, sex, educational achievement, cognitive measures, or APOE genotype.
The final sample of subjects ranged in age from 50 to 82 years and was stratified according to APOE4 genetic risk. Of the 30 subjects (27 white and 3 Asian), 14 were APOE4 carriers and 16 were noncarriers. All APOE4 carriers had the APOE 3/4 genotype. Of the 16 APOE4 noncarriers, 2 had the APOE 2/3 genotype and 14 had the APOE 3/3 genotype. After complete description of the study to participants, we obtained written informed consent.
DNA ANALYSIS
We obtained DNA from blood samples. APOE genotypes were determined using standard techniques as previously described.22
OBJECTIVE AND SUBJECTIVE MEMORY TESTS
A neuropsychological battery was administered to subjects as previously described,32 but we included only the objective tests of verbal and nonverbal memory for the present analyses. We included tests of immediate and delayed paragraph recall36 (Wechsler Memory Scale–Revised logical memory), word list learning (Buschke-Fuld Selective Reminding Test total recall),37 figure learning (Benton Visual Retention Test),38 and delayed figure recall (Rey-Osterrieth Complex Figure).39 We evaluated gross cognitive functioning using the Mini-Mental State Examination.40
We assessed self-appraisal of everyday memory functioning using the MFQ, a popular instrument with high internal consistency and moderate concurrent validity with memory performance measures.41 The MFQ consists of 64 items rated on a 7-point scale and provides 4 unit-weight factor scores measuring frequency of forgetting, seriousness of forgetting, retrospective functioning (changes in current memory ability relative to earlier life), and mnemonics use (memory support techniques, mostly including external aids such as calendars and appointment books). Higher scores indicate higher (more favorable) levels of perceived memory functioning.
NEUROIMAGING
Subjects underwent positron emission tomography (PET) as previously described.42-43 In brief, they were imaged in the supine position with low ambient noise, and their eyes and ears were unoccluded. Intravenous lines were placed 10 to 15 minutes before tracer injection of 10 mCi of fluorodeoxyglucose F18. All imaging was performed 40 minutes after fluorodeoxyglucose F18 injection using the CTI/Seimens 831-08 EXACT HR (Seimens Corp, Hoffman Estates, Ill) or the CTI 962 EXACT HR+ scanner (15-63 image planes), and the duration of PET was 40 minutes. We acquired images of 21 subjects at baseline and follow-up using the 962 scanner; images of the 9 remaining subjects were acquired using the 831 scanner at baseline and the 962 scanner at follow-up. Because 2 scanners were used to acquire images (because of scanner availability), computed tomographic images were reconstructed and axially smoothed to give comparable spatial resolution (full width at half-maximum, 0.65 cm in the axial plane and 0.8 cm in the image plane). The procedure has been previously described.32 Because the images from both scanners were reconstructed to have the same spatial resolution and because the same procedure was used for attenuation correction, no systematic differences are expected between images obtained from these 2 scanners. At baseline, 21.4% (3/14) of APOE4 carriers and 37.5% (6/16) of APOE4 noncarriers were imaged using the 831 scanner. At follow-up, all subjects were imaged using the 962 scanner. Images were acquired parallel to the canthomeatal line; a transmission measurement was used for attenuation correction.
Baseline brain MR images were obtained using a 1.5-T magnet or a 3-T magnet (General Electric MR Signa; General Electric Medical Systems, Milwaukee, Wis). At baseline, 21.4% (3/14) of APOE4 carriers and 31.3% (5/16) of APOE4 noncarriers were imaged using the 3-T magnet. At follow-up, all subjects were imaged using the 3-T magnet. Thirty-six transaxial planes were collected throughout the brain volume, superior to the cerebellum. For MR imaging registration (using PET for anatomical metabolic data localization with reference to individual structural anatomy), we acquired a dual-echo, fast spin-echo series using a 24-cm field of view and a 256 x 256–pixel matrix with 3-mm section thickness with no gaps between sections (repetition times, 6000 milliseconds [3-T magnet] and 2000 milliseconds [1.5-T magnet]; echo times, 17 milliseconds [first echo] and 85 milliseconds [second echo] [3-T magnet] and 30 milliseconds [first echo] and 90 milliseconds [second echo] [1.5-T magnet]). An intermodality image coregistration program44 that performs image segmentation and simulation as preprocessing procedures was used to coregister PET and baseline MR images of each subject. Region of interest (ROI) analyses were then performed.
ROI ANALYSIS
Two persons blinded to clinical diagnosis and genotype manually drew the ROI in the axial plane on registered MR images for each subject. We assessed interrater reliability for the 2 persons drawing the ROIs by calculating the spatial overlap of ROIs drawn twice for 10 subjects to ensure that the mean ± SD reliability was 0.85 ± 0.04 or higher.
We designated rules for ROI drawing based on the identification of sulcal and gyral landmarks using the atlas of Talairach and Tournoux.45 As previously described,32 the ROIs pertaining to memory processing and AD involve the right and left hemispheres and comprise the following: (1) the inferoparietal cortex (bounded anteriorly by the postcentral sulcus, superiorly by the intraparietal sulcus, inferiorly by the Sylvian fissure, and posteriorly by the antero-occipital sulcus), (2) the posterior cingulate cortex (surrounded by the cingulate sulcus posterior to the corpus callosum [retrosplenial region]), (3) the dorsolateral prefrontal cortex (defined by the middle frontal gyrus and the gray matter surrounding the inferofrontal sulcus and corresponding approximately to Brodmann areas 9 and 46), (4) the inferotemporal cortex (surrounding the inferotemporal sulcus at the base of the temporal lobes), (5) the superotemporal cortex (located immediately posterior to the transverse temporal gyri, from the Sylvian fissure to the superotemporal sulcus), and (6) the mediotemporal cortex (defined by the section through the center of the long axis of the hippocampus that included the amygdala, hippocampus, and parahippocampal gyrus). All ROIs were identified in their entirety, but for each region we located the middle section across planes that best represented the ROI for each subject, to avoid partial volume effects and difficulties with boundary demarcations between subjects. The whole-brain ROI, drawn manually around the brain on each axial plane, included cortex, subcortical gray matter, and the midbrain to the level of the pons and excluded the cerebellum.
Exclusion of white matter from the ROIs was done first by segmentation, then manually by tightly adhering to gray matter while drawing the ROI boundaries, and then by thresholding. For thresholding, only the pixel values within 30% of the maximal pixel value within each ROI were used when calculating the mean ROI values. The choice of the 30% threshold was made as a compromise between the need to minimize the effects of the statistical noise of the image and the variability of ROI drawing on the calculated ROI values.46 The ROI values were normalized to the whole-brain value at that same level. Investigators (L.E., P.S., and S.-C.H.) blinded to clinical and genetic findings analyzed the image data.
Written informed consent was obtained in accord with the procedures set by the UCLA Human Subjects Protection Committee. Genetic test results were not released to participants.
STATISTICAL ANALYSIS
We screened data for outliers and violations of normality assumptions. t Tests and  2 tests were performed for comparisons of APOE4 carriers and noncarriers on demographics, clinical variables, and MFQ factor scores (frequency of forgetting, seriousness of forgetting, retrospective functioning, and mnemonics use).
To study the associations between the 4 MFQ factor scores and changes on the 5 objective memory tests for APOE4 carriers and noncarriers, we performed separate univariate analyses of variance, with change scores (follow-up scores minus baseline scores) for each memory test as the dependent variable. The MFQ factor scores, APOE4 genetic risk, and their interaction were the independent variables. Age was a covariate in all analyses. Given the relationship between depression and subjective memory, we also controlled for depressive severity by including the Hamilton Rating Scale for Depression scores as covariates in all analyses. All tests were 2-tailed, and in follow-up univariate analyses we adopted a significance level of P=.05 after Bonferroni correction.
To study the associations between MFQ factor scores and metabolic changes (follow-up rates minus baseline rates), we computed a repeated-measures analysis of covariance with APOE4 genetic risk as the intersubject classification variable and the ROIs (left and right) of each of the following regions as the intrasubject classification variable: dorsolateral prefrontal cortex, posterior cingulate cortex, inferoparietal cortex, and temporal cortex (mean of the mediotemporal, inferotemporal, and superotemporal regions). Separate models were fitted for each of the MFQ factor scores. Each factor score and its interaction with APOE4 genetic risk were used as the independent variables in the repeated-measures analysis of variance. Age, educational achievement, and Hamilton Rating Scale for Depression scores were used as covariates. All tests were 2-tailed, and we adopted a significance level of P=.05.
RESULTS
Table 1 summarizes the demographic and clinical information. Baseline comparisons of APOE4 carriers and noncarriers indicated no significant differences in age, sex, educational achievement, family history of AD, or Hamilton Rating Scale for Depression scores. The APOE4 carriers and noncarriers did not differ significantly on objective memory test scores or on MFQ factor scores (Table 2) at baseline. Although the groups did not differ significantly in age or baseline test performances, given the relationship between APOE4 genetic risk and age, we addressed the possibility that the slightly younger APOE4 carriers may have been mildly cognitively impaired compared with noncarriers. We conducted analyses of variance to determine if there was an interaction effect of age x APOE4 genetic risk on the results of the baseline memory tests and the Mini-Mental State Examination. Our findings indicated no significant interactions between age and genetic risk for any of these measures.
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Table 1. Baseline Demographic and Clinical Characteristics for Subject Groups*
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Table 2. Baseline Test Scores for Subject Groups*
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The APOE4 carriers and noncarriers did not differ significantly in baseline cerebral metabolism for any ROI (Table 2). After Bonferroni correction, there were no significant declines in regional metabolism in either genetic risk group after 2 years. For APOE4 noncarriers, only the right dorsolateral prefrontal cortex demonstrated a 2% decline after 2 years (P = .04), which was nonsignificant after Bonferroni correction.
The univariate analyses of variance examining the relationship between subjective memory complaints and objective memory test result changes showed that none of the MFQ factor scores was associated with memory test changes for either APOE4 genetic risk group. The repeated-measures analyses of covariance examining the relationship between subjective memory complaints and metabolic changes showed that frequency of forgetting was significantly correlated with global cerebral metabolic decline (F1,23 = 8.34, P = .01) regardless of APOE4 genetic risk (Figure A). With increasing complaints of frequency of forgetting, glucose metabolism (after 2 years) decreased in all regions. Furthermore, we found a significant interaction between mnemonics use and APOE4 genetic risk (F1,23 = 5.47, P = .03) with regional cerebral metabolic decline, which differed among APOE4 carriers vs noncarriers. For APOE4 carriers only, increased mnemonics use was significantly associated with a decline in cerebral metabolism over time (t23 = 2.24, P = .03).
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Figure. Correlation of baseline Memory Functioning Questionnaire factor scores with percentage point changes in cerebral metabolism over 2 years. A, A significant correlation between a higher degree of frequency of forgetting and percentage point decline in global cerebral metabolism was found for all subjects regardless of apolipoprotein E-IV (APOE4) genotype. B, A significant interaction was found between mnemonics use and APOE4 status on percentage point change in medial temporal metabolism. For only APOE4 carriers, greater mnemonics use was significantly associated with a decline in medial temporal metabolism.
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We conducted separate analyses for the temporal, parietal, dorsolateral prefrontal, and posterior cingulate regions to assess which ROIs were associated with subjective memory complaints. The ROIs were averaged over the left and right hemispheres. For APOE4 carriers, increased mnemonics use at baseline was associated with metabolic decline in the temporal ROIs, while for APOE4 noncarriers there was no such association (F1,23 = 4.53, P = .04) (Figure B). No other MFQ factor score main effects or MFQ factor score x APOE genetic risk interactions reached statistical significance.
To assess scanner comparability, we reran the analyses with only the 21 subjects who were imaged using the same scanner at both periods. We found a significant relationship between greater complaints of frequency of forgetting at baseline and global decline over time for all subjects (t14 = –14.7, P<.001). A trend toward an association between greater mnemonics use at baseline and temporal lobe metabolic decline was found only for APOE4 carriers (t14 = –1.8, P = .09). Overall, the findings suggest that scanner differences did not affect the study results.
To ensure homogeneous group comparisons, we reran all analyses comparing only subjects having the APOE 3/3 genotype with subjects having the APOE 3/4 genotype. All results were identical to those conducted with the full sample.
At the time of the follow-up assessment, 1 subject was taking antidepressant medications. Analyses were rerun excluding this individual, and the findings were identical.
COMMENT
To our knowledge, the present findings are the first to indicate that the degree of self-awareness of memory difficulties is associated with longitudinal declines in underlying cerebral metabolism, as measured using fluorodeoxyglucose F18–PET. Complaints of greater frequency of forgetting at baseline are associated with global cerebral metabolic decline at follow-up for all subjects regardless of APOE4 genetic risk. Self-reports of increased use of compensatory memory strategies (ie, mnemonics use) correlate with glucose metabolic decline in the temporal brain regions in APOE4 carriers but not in noncarriers. The findings suggest that the correlation between complaints of frequent forgetting and global decreases47 in cortical metabolism is related to normal aging and not to underlying APOE4 genetic risk of AD, as it was previously found that prefrontal decreases48 occur in normal aging as well.
In contrast, the association between increasing mnemonics use and temporal metabolic decline suggests an awareness of underlying physiological deficits related to dementia risk. The temporal ROIs, which included medial temporal lobe and lateral temporal association cortices, are areas that subserve memory functions49-51 and demonstrate neuropathological changes in preclinical and early AD.52-53 The temporal or temporal-parietal regions are among the earliest areas that demonstrate hypometabolism54-55 or hypoperfusion56 in persons with AD, in unaffected relatives of persons with familial AD,57 in unaffected monozygotic cotwins of persons with AD,55 and in nondemented APOE4 carriers.32, 58 In longitudinal investigations, hypometabolism in the medial temporal, lateral temporal, or temporal-parietal regions has predicted the conversion of isolated memory impairment or mild cognitive impairment to AD,59-60 and APOE4 carriers with declining cognitive function demonstrate temporal neocortical reductions in glucose metabolism.61 The prognostic implications would have been stronger if APOE4 carriers in the present study had demonstrated objective cognitive impairment relative to noncarriers; however, carriers were highly educated, and neuropsychological tests may be less sensitive to subtle declines in such persons because of their high levels of cognitive reserve.62 In addition, neocortical hypometabolism may precede objective memory deficits because of the brain's compensatory abilities or cognitive reserve,54 and it follows that such hypometabolism may have been ongoing in our APOE4 carriers at the time of their enrollment in this study, although there were no significant group differences in baseline regional metabolism. Therefore, it is possible that persons with a genetic risk for AD may notice cognitive decline and use mnemonics to compensate for real memory changes before objective clinical detection.
Our results suggest differential predictive validity for metabolic decline depending on the type of memory complaint. In parallel, previous research indicates that some types of subjective memory self-ratings are more predictive of objective memory test performance than others.63
The present study expands on previous investigations of subjective memory complaints and underlying brain function in persons at risk for cognitive decline. Patterns of activation involving the lateral and medial temporal regions during performance of an episodic memory task, as assessed by functional MR imaging, distinguished between persons with memory complaints with early AD or major depression and healthy controls without memory complaints.19 The patients with AD demonstrated decreased activation in the medial, mid, and lateral temporal regions compared with controls, particularly in the right hippocampus, compared with patients with major depression. Previous cross-sectional studies20-21 examined the relationship between MFQ factor scores and cerebral metabolism in a sample of persons with and without a family history of AD who had age-associated memory impairment. Consistent with the present findings, group differences in resting-state regional cerebral glucose metabolism and memory measures were minimal. Few objective memory measures correlated with metabolic rates. Less frequent mnemonics use correlated with increased frontal metabolic activity, suggesting that memory complaints may be a more sensitive indicator of decreased frontal lobe activity than objective memory tests. In the previous cross-sectional studies,20-21 APOE4 genetic risk was not a variable, which may explain why the present study did not replicate the frontal metabolic finding. Overall, the present results are consistent with previous findings that subjective memory complaints are sensitive indicators of underlying brain function and extend the findings to support that memory complaints are associated with regional glucose metabolic decline in APOE4 carriers.19-21
In the present study, APOE4 carriers did not differ significantly from noncarriers in subjective memory complaints, which was inconsistent with some previous reports. The APOE4 allele may be overrepresented in persons with memory complaints and a family history of AD,26 in persons with memory complaints and age-related cognitive decline,29 and in older depressed adults.27 In the present study, family histories of dementia were not significantly different between APOE4 carriers and noncarriers, subjects in the present investigation were less cognitively impaired (mean Mini-Mental State Examination score, >28.5) compared with persons with age-related cognitive decline in the study by Blesa et al29 (mean Mini-Mental State Examination score, 24.4), and our subjects were not depressed. In another study30 of APOE4 carriers, subjective memory complaints were associated with accelerated cognitive decline on a test assessing the speed of information processing but not on tests of immediate or delayed recall. In the present study, APOE4 carriers and noncarriers did not differ in the prevalence of memory complaints or in the rate of decline on tests of immediate or delayed memory. Findings in a previous cross-sectional study64 among a slightly larger overlapping sample demonstrated that APOE4 carriers had significantly more complaints about retrospective functioning than noncarriers. Discrepancies may be due to sample composition and uncorrected statistical test results in the previous study. As emphasized in the previous study,64(p1037) although results were statistically significant, group differences on the MFQ factor scores were small, and 95% confidence intervals for the means overlapped between groups.
There are several limitations of the present study. The sample was not representative of the general clinical population, as most subjects were highly educated and white. Only 30 (5.2%) of 573 persons who volunteered for the study were included. Volunteers with other possible health risk factors for cognitive impairment, including those that may interact with the APOE4 genetic risk to increase the risk for dementia (eg, cerebral vascular disease), were excluded. It is possible that very mild cases of dementia were undetected, which may have affected metabolic rate findings, although detailed screenings were conducted at baseline to rule out dementia or mild cognitive impairment. Because this is a naturalistic study, we cannot rule out that right censoring may have occurred, meaning that APOE4 carriers were more highly represented among those excluded because of baseline cognitive deficits (eg, mild cognitive impairment) compared with noncarriers. Finally, the present study is the first known report of a correlation between subjective memory complaints and subsequent cerebral metabolic decline in genetically at-risk persons, and replication of these findings is warranted.
Our results support the validity of memory complaints for individuals by indicating that the degree of memory complaints is reflected in objective metabolic changes and suggest that complaints should be taken seriously. Regardless of APOE4 genetic risk, complaints of increased frequency of forgetting predicted global cerebral metabolic decline, and such metabolic changes may be indicative of normal aging. Specific memory complaints related to the use of compensatory strategies in APOE4 carriers may provide additional information regarding the potential for metabolic decline in the regions that subserve memory and that are associated with AD. Self-reported use of compensatory strategies may be useful in identifying persons for further study or for increased clinical monitoring. Distinguishing between general complaints and behavioral compensation may be important in future studies assessing the validity of memory complaints.
AUTHOR INFORMATION
Correspondence: Linda Ercoli, PhD, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, 760 Westwood Plaza, Room 88-201, Los Angeles, CA 90024-1759 (lercoli{at}mednet.ucla.edu).
Submitted for Publication: April 22, 2004; final revision received September 12, 2005; accepted September 14, 2005.
Funding/Support: This study was supported by grants MH52453, AG13308, AG10123, RG296051, NS31153, NS26630, AG05128, AG100784, AG16570, and AG11268 from the National Institutes of Health, Bethesda, Md; by grant M01 RR00865 from the US Public Health Service, Hyattsville, Md; by grant IIRG94101 from the Alzheimer's Association, Chicago, Ill; by grant 95-23330 from the California Department of Health Services, Sacramento; by the US Department of Energy, Washington, DC; by the Sidell-Kagan Foundation, Los Angeles; by the Montgomery Street Foundation, San Francisco, Calif; by the Fran and Ray Stark Foundation Fund for Alzheimer's Disease Research, Los Angeles; by the Parlow-Solomon Chair on Aging, David Geffen School of Medicine at UCLA; by the Brain Mapping Medical Research Organization, Los Angeles; by the Ahmanson Foundation, Beverly Hills, Calif; by the Tamkin Foundation, Los Angeles; by the Louis and Harold Price Foundation, Inc, New York, NY; and by the Larry L. Hillblom Foundation, Inc, Petaluma, Calif.
Previous Presentation: This study was presented in part at the 16th Annual Meeting of the American Association for Geriatric Psychiatry, March 2, 2003; Honolulu, Hawaii.
Acknowledgment: We thank Andrea Kaplan; Deborah Dorsey, RN; Gwendolyn Byrd, MA; and Teresann Crowe-Lear for administrative assistance.
Author Affiliations: Departments of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior (Drs Ercoli, Siddarth, Miller, Bookheimer, Wright, and Small), and Molecular and Medical Pharmacology, David Geffen School of Medicine (Drs Huang and Phelps), and Center on Aging (Dr Small), University of California, Los Angeles.
REFERENCES
| |
1. Bassett SS, Folstein MF. Memory complaint, memory performance, and psychiatric diagnosis: a community study. J Geriatr Psychiatry Neurol. 1993;6:105-111.
ISI
| PUBMED
2. Jonker C, Launer LJ, Hooijer C, Lindeboom J. Memory complaints and memory impairment in older individuals. J Am Geriatr Soc. 1996;44:44-49.
ISI
| PUBMED
3. Blazer DG, Hays JC, Fillenbaum GG, Gold DT. memory complaint as a predictor of cognitive decline. J Aging Health. 1997;9:171-184.
FREE FULL TEXT
4. Jonker C, Geerlings MI, Schmand B. Are memory complaints predictive for dementia? a review of clinical and population-based studies. Int J Geriatr Psychiatry. 2000;15:983-991.
FULL TEXT
|
ISI
| PUBMED
5. Schofield PW, Marder K, Dooneief G, Jacobs DM, Sano M, Stern Y. Association of subjective memory complaints with subsequent cognitive decline in community-dwelling elderly individuals with baseline cognitive impairment. Am J Psychiatry. 1997;154:609-615.
ABSTRACT
6. Schmand B, Jonker C, Geerlings MI, Lindeboom J. Subjective memory complaints may announce dementia. Neurology. 1996;46:121-125.
FREE FULL TEXT
7. Schmand B, Jonker C, Geerlings MI, Lindeboom J. Subjective memory complaints in the elderly: depressive symptoms and future dementia. Br J Psychiatry. 1997;171:373-376.
FREE FULL TEXT
8. Jorm AF, Christensen H, Korten AE, Jacomb PA, Henderson AS. Memory complaints as a precursor of memory impairment in older people: a longitudinal analysis over 7-8 years. Psychol Med. 2001;31:441-449.
ISI
| PUBMED
9. Tobiansky R, Blizard R, Livingston G, Mann A. The Gospel Oak Study stage IV: the clinical relevance of subjective memory impairment in older people. Psychol Med. 1995;25:779-786.
ISI
| PUBMED
10. Geerlings MI, Jonker C, Bouter LM, Herman JA, Schmand B. Association between memory complaints and incident Alzheimer's disease in elderly people with normal baseline cognition. Am J Psychiatry. 1999;156:531-537.
FREE FULL TEXT
11. Wang L, van Belle G, Crane P, Kukull W, Bowen J, McCormick WC, Larson EB. Subjective memory deterioration and future dementia in people aged 65 and older. J Am Geriatr Soc. 2004;52:2045-2051.
FULL TEXT
|
ISI
| PUBMED
12. O’Brien JT, Beats B, Hill K, Howard R, Sahakian B, Levy R. Do subjective memory complaints precede dementia? a three-year follow-up of patients with supposed "benign senescent forgetfulness." Int J Geriatr Psychiatry. 1992;7:481-486.
FULL TEXT
|
ISI
13. Hänninen T, Reinikainen KJ, Helkala EL, Koivisto K, Mykkanen L, Laakso M, Pyörälä K, Riekkinen PJ. Subjective memory complaints and personality traits in normal elderly subjects. J Am Geriatr Soc. 1994;42:1-4.
ISI
| PUBMED
14. Jorm AF, Christensen H, Korten AE, Henderson AS, Jacomb PA, Mackinnon A. Do cognitive complaints either predict future cognitive decline or reflect past cognitive decline? a longitudinal study of an elderly community sample. Psychol Med. 1997;27:91-98.
FULL TEXT
|
ISI
| PUBMED
15. Smith GE, Petersen RC, Ivnik RJ, Malec JF, Tangalos EG. Subjective memory complaints, psychological distress, and longitudinal change in objective memory performance. Psychol Aging. 1996;11:272-279.
FULL TEXT
|
ISI
| PUBMED
16. Flicker C, Ferris SH, Reisberg B. A longitudinal study of cognitive function in elderly persons with subjective memory complaints. J Am Geriatr Soc. 1993;41:1029-1032.
ISI
| PUBMED
17. Taylor JL, Miller TP, Tinklenberg JR. Correlates of memory decline: a four-year longitudinal study of older adults with memory complaints. Psychol Aging. 1992;7:185-193.
FULL TEXT
|
ISI
| PUBMED
18. West RL, Boatwright LK, Schleser R. The link between memory performance, self-assessment, and affective status. Exper Aging Res. 1984;10:197-200.
19. Gron G, Bittner D, Schmitz B, Wunderlich AP, Riepe MW. Subjective memory complaints: objective neural markers in patients with Alzheimer's disease and major depressive disorder. Ann Neurol. 2002;51:491-498.
FULL TEXT
|
ISI
| PUBMED
20. Small GW, Okonek A, Mandelkern MA, La Rue A, Chang L, Khonsary A, Ropchan JR, Blahd WH. Age-associated memory loss: initial neuropsychological and cerebral metabolic findings of a longitudinal study. Int Psychogeriatr. 1994;6:23-44.
FULL TEXT
| PUBMED
21. Small GW, Komo S, La Rue A, Kaplan A, Mandelkern MA. Memory self-appraisal and cerebral glucose metabolism in age-associated memory impairment. Am J Geriatr Psychiatry. 1995;3:132-143.
FULL TEXT
|
ISI
22. Saunders AM, Strittmatter WJ, Schmechel D, St George-Hyslop PH, Pericak-Vance MA, Joo SH, Rosi BL, Gusella JF, Crapper-MacLachlan DR, Alberts MJ, Hulette C, Crain B, Goldgaber D, Roses AD. Association of apolipoprotein E allele  4 with late-onset familial and sporadic Alzheimer's disease. Neurology. 1993;43:1467-1472.
FREE FULL TEXT
23. Okuizumi K, Onodera O, Tanaka H, Kobyashi H, Tsuji S, Takahashi H, Oyanagi K, Seki K, Tanaka M, Naruse S, Miyatake T, Mizusawa H, Kanazawa I. ApoE-4 and early-onset Alzheimer's [letter]. Nat Genet. 1994;7:10-11.
ISI
| PUBMED
24. Corder EH, Saunders AM, Strittmatter WJ, Schmechel DE, Gaskell PC, Small GW, Roses AD, Haines JL, Pericak-Vance MA. Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer's disease in late onset families. Science. 1993;261:921-923.
FREE FULL TEXT
25. Corder EH, Saunders AM, Risch MJ, Strittmatter WJ, Schmechel DE, Gaskell PC Jr, Rimmler JB, Locke PA, Conneally PM, Schmader KE, Small GW, Roses AD, Haines JL, Pericak-Vance MA. Protective effect of apolipoprotein E type 2 allele for late onset Alzheimer disease. Nat Genet. 1994;7:180-183.
FULL TEXT
|
ISI
| PUBMED
26. Laws SM, Clarnette RM, Taddei K, Martings G, Paton A, Hallmayer J, Almeida OP, Groth DM, Gandy SE, Forstl H, Martins RN. APOE-4 and APOE-491A polymorphisms in individuals with subjective memory loss. Mol Psychiatry. 2002;7:768-775.
FULL TEXT
|
ISI
| PUBMED
27. Stewart R, Russ C, Richards M, Brayne C, Lovestone S, Mann A. Depression, APOE genotype and subjective memory impairment: a cross-sectional study in an African-Caribbean population. Psychol Med. 2001;31:431-440.
ISI
| PUBMED
28. Small GW, Chen ST, Komo S, Ercoli L, Miller K, Siddarth P, Kaplan A, Dorsey D, Lavretsky H, Saxena S, Bookheimer SY. Memory self-appraisal and depressive symptoms in people at genetic risk for Alzheimer's disease. Int J Geriatr Psychiatry. 2001;16:1071-1077.
FULL TEXT
|
ISI
| PUBMED
29. Blesa R, Adroer R, Santacruz P, Ascaso C, Tolosa E, Oliva R. High apolipoprotein E 4 allele frequency in age-related memory decline. Ann Neurol. 1996;39:548-551.
FULL TEXT
|
ISI
| PUBMED
30. Dik MG, Jonker C, Comijs HC, Bouter LM, Twisk JW, van Kamp GJ, Deeg DJ. Memory complaints and APOE-4 accelerate cognitive decline in cognitively normal elderly. Neurology. 2001;57:2217-2222.
FREE FULL TEXT
31. Gilewski MJ, Zelinski EM, Schaie KW. The Memory Functioning Questionnaire for assessment of memory complaints in adulthood and old age. Psychol Aging. 1990;5:482-490.
FULL TEXT
|
ISI
| PUBMED
32. Small GW, Ercoli LM, Silverman DH, Huang SC, Komo S, Bookheimer SY, Lavretsky H, Miller K, Siddarth P, Rasgon NL, Mazziotta JC, Saxena S, Wu HM, Mega MS, Cummings JL, Saunders AM, Pericak-Vance MA, Roses AD, Barrio JR, Phelps ME. Cerebral metabolic and cognitive decline in persons at genetic risk for Alzheimer's disease. Proc Natl Acad Sci U S A. 2000;97:6037-6042.
FREE FULL TEXT
33. Flicker C, Ferris SH, Reisberg B. Mild cognitive impairment in the elderly: predictors of dementia. Neurology. 1991;41:1006-1009.
FREE FULL TEXT
34. Smith GE, Petersen RC, Parisi JE, Ivnik RJ. Definition, course and outcome of mild cognitive impairment. Aging Neuropsychol Cognition. 1996;3:141-147.
FULL TEXT
35. Hamilton M. A Rating Scale for Depression. J Neurol Neurosurg Psychiatry. 1960;23:56-62.
FREE FULL TEXT
36. Wechsler D. Wechsler Adult Intelligence Scale–Revised. San Antonio, Tex: Psychological Corp; 1981.37. Buschke H, Fuld PA. Evaluating storage, retention and retrieval in disordered memory and learning. Neurology. 1974;24:1019-1025.
FREE FULL TEXT
38. Benton AL. The Revised Visual Retention Test. New York, NY: Psychological Corp; 1974.39. Osterrieth PA. Le test de copie d’une figure complexe. Arch Psychol (Frankf). 1944;30:206-356.
40. Folstein MF, Folstein SE, McHugh PR. "Mini-Mental State": a practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975;12:189-198.
FULL TEXT
|
ISI
| PUBMED
41. Zelinski EM, Gilewski MJ, Anthony-Bergstone CR. Memory Functioning Questionnaire: concurrent validity with memory performance and self-reported memory failures. Psychol Aging. 1990;5:388-399.
FULL TEXT
|
ISI
| PUBMED
42. Phelps ME, Huang SC, Hoffman EJ, Selin C, Sokoloff L, Kuhl DE. Tomographic measurement of local cerebral glucose metabolic rate in humans with (F-18) 2-fluoro-2-deoxy-D-glucose: validation of method. Ann Neurol. 1979;6:371-388.
FULL TEXT
|
ISI
| PUBMED
43. Huang SC, Phelps ME, Hoffman EJ, Sideris K, Selin CJ, Kuhl DE. Noninvasive determination of local cerebral metabolic rate of glucose in man. Am J Physiol. 1980;238:E69-E82.
FREE FULL TEXT
44. Lin KP, Huang SC, Baxter LR, Phelps ME. A general technique for interstudy registration of multifunction and multimodality images. IEEE Trans Nucl Sci. 1994;41:2850-2855.
FULL TEXT
|
ISI
45. Talairach J, Tournoux P. Coplanar Stereotaxic Atlas of the Human Brain: Three-Dimensional Proportional System: An Approach to Cerebral Imaging. New York, NY: Thieme-Stratton Inc; 1988.46. Rottenberg DA, Moeller JR, Strother SC, Dhawan V, Sergi ML. Effects of percent thresholding on the extraction of [18F] fluorodeoxyglucose positron emission tomographic region-of-interest data. J Cereb Blood Flow Metab. 1991;11:A83-A88.
ISI
| PUBMED
47. Willis MW, Ketter TA, Kimbrell TA, George MS, Herscovitch P, Danielson AL, Benson BE, Post RM. Age, sex and laterality effects on cerebral glucose metabolism in healthy adults. Psychiatry Res. 2002;114:23-37.
ISI
| PUBMED
48. Mielke R, Kessler J, Szelies B, Herholz K, Wienhard K, Heiss WD. Normal and pathological aging: findings of positron-emission-tomography. J Neural Transm. 1998;105:821-837.
FULL TEXT
|
ISI
| PUBMED
49. Ojemann GA, Schoenfield-McNeill J, Corina DP. Anatomic subdivisions in human temporal cortical neuronal activity related to recent verbal memory. Nat Neurosci. 2002;5:64-71.
FULL TEXT
|
ISI
| PUBMED
50. Mummery CJ, Patterson K, Hodges JR, Wise RJ. Generating ‘tiger’ as an animal name or a word beginning with T: differences in brain activation. Proc Biol Sci. 1996;263:989-995. [published correction appears in Proc R Soc Lond B Biol Sci. 1996;263:1755-1756].51. Desgranges B, Baron JC, Eustache F. The functional neuroanatomy of episodic memory: the role of the frontal lobes, the hippocampal formation, and other areas. Neuroimage. 1998;8:198-213.
FULL TEXT
|
ISI
| PUBMED
52. Braak H, Braak E. Neuropathological staging of Alzheimer-related changes. Acta Neuropathol (Berl). 1991;82:239-259.53. Price JL, Davis PB, Morris JC, White DL. The distribution of tangles, plaques and related immunohistochemical markers in healthy aging and Alzheimer's disease. Neurobiol Aging. 1991;12:295-312.
FULL TEXT
|
ISI
| PUBMED
54. Grady CL, Haxby JV, Horwitz B, Sundaram M, Berg G, Schapiro M, Friedland RP, Rapoport SI. Longitudinal study of the early neuropsychological and cerebral metabolic changes in dementia of the Alzheimer type. J Clin Exp Neuropsychol. 1988;10:576-596.
ISI
| PUBMED
55. Järvenpää T, Räihä I, Kaprio J, Koskenvuo M, Laine M, Kurki T, Vahlberg T, Viljanen T, Ahonen K, Rinne J. Regional cerebral glucose metabolism in monozygotic twins discordant for Alzheimer's disease. Dement Geriatr Cogn Disord. 2003;16:245-252.
FULL TEXT
|
ISI
| PUBMED
56. Cohen RM, Andreason PJ, Sunderland T. The ratio of mesial to neocortical temporal lobe blood flow as a predictor of dementia. J Am Geriatr Soc. 1997;45:329-333.
ISI
| PUBMED
57. Kennedy AM, Frackowiak RSJ, Newman SK, Bloomfield PM, Seaward J, Roques P, Lewington G, Cunningham VJ, Rossor MN. Deficits in cerebral glucose metabolism demonstrated by positron emission tomography in individuals at risk of familial Alzheimer's disease. Neurosci Lett. 1995;186:17-20.
FULL TEXT
|
ISI
| PUBMED
58. Reiman EM, Caselli RJ, Yun LS, Chen K, Bandy D, Minoshima S, Thibodeau SN, Osborne D. Preclinical evidence of Alzheimer's disease in persons homozygous for the 4 allele for apolipoprotein E. N Engl J Med. 1996;334:752-758.
FREE FULL TEXT
59. Berent S, Giordani B, Foster N, Minoshima S, Lajiness-O’Neill R, Koeppe R, Kuhl DE. Neuropsychological function and cerebral glucose utilization in isolated memory impairment and Alzheimer's disease. J Psychiatr Res. 1999;33:7-16.
FULL TEXT
|
ISI
| PUBMED
60. Arnaiz E, Jelic V, Almkvist O, Wahlund LO, Winblad B, Valind S, Nordberg A. Impaired cerebral glucose metabolism and cognitive functioning predict deterioration in mild cognitive impairment. Neuroreport. 2001;12:851-855.
FULL TEXT
|
ISI
| PUBMED
61. de Leon MJ, Convit A, Wolf OT, Tarshish CY, DeSanti S, Rusinek H, Tsui W, Kandil E, Scherer AJ, Roche A, Imossi A, Thorn E, Bobinski M, Caraos C, Lesbre P, Schlyer D, Poirer J, Reisberg B, Fowler J. Prediction of cognitive decline in normal elderly subjects with 2-[18F]fluoro-2-deoxy-D-glucose/positron-emission tomography (FDG/PET). Proc Natl Acad Sci U S A. 2001;98:10966-10971.
FREE FULL TEXT
62. Rentz DM, Huh TJ, Faust RR, Budson AE, Scinto LF, Sperling RA, Daffner KR. Use of IQ-adjusted norms to predict progressive cognitive decline in highly intelligent older individuals. Neuropsychology. 2004;18:38-49.
FULL TEXT
|
ISI
| PUBMED
63. Cipolli C, Neri M, Andermarcher E, Pinelli M, Lalla M. Self-rating and objective memory testing of normal and depressed elderly. Aging (Milano). 1990;2:39-48.
PUBMED
64. Small GW, Chen ST, Komo S, Ercoli L, Bookheimer S, Miller K, Lavretsky H, Saxena S, Kaplan A, Dorsey D, Scott WK, Saunders AM, Haines JL, Roses AD, Pericak-Vance MA. Memory self-appraisal in middle-aged and older adults with the apolipoprotein E-4 allele. Am J Psychiatry. 1999;156:1035-1038.
FREE FULL TEXT
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