Depressive symptoms, sex, and risk for Alzheimer's disease

Persistent depressive symptoms and cognitive function in late midlife: the Whitehall II study

OBJECTIVE

Depression has been widely linked to poor cognition and dementia in the elderly. However, comorbidity at older ages does not allow an assessment of the role of mental health as a risk factor for cognitive outcomes. We examined the association between depressive symptoms, measured 6 times over an 18-year period, and cognitive deficits in late midlife.

METHOD

Of the 10,308 participants in the Whitehall II study, 4,271 men and women (aged 35-55 years at baseline) were followed up for 18 years, during which depressive symptoms were assessed 6 times using the General Health Questionnaire depression subscale. The follow-up was from 1985-1988 to 2002-2004. Cognition was assessed at the most recent wave (2002-2004, mean age 61 years, range 50-74 years) using 6 tests: memory, reasoning, vocabulary, 2 tests of verbal fluency, and the MMSE (Mini Mental State Examination). Cognitive deficit was defined as MMSE score <28 and performance in the worst sex-specific quintile for the other tests.

RESULTS

History of depressive symptoms, once or more in the 6 times assessed, had a weak association with some of the cognitive tests. However, in analysis adjusted for sociodemographic variables, diabetes, coronary heart disease, hypertension, stroke, and antidepressant use, persistent depressive symptoms (4-6 times) were associated with cognitive deficits on all tests: memory (OR=1.91; 95% CI, 1.36-2.67), reasoning (OR=1.60; 95% CI, 1.15-2.20), vocabulary (OR=1.75; 95% CI, 1.27-2.41), phonemic fluency (OR=1.40; 95% CI, 1.00-1.94), semantic fluency (OR=1.68; 95% CI, 1.20-2.35), and the MMSE (OR=1.76; 95% CI, 1.25-2.50).

CONCLUSIONS

Our data show that depressive episodes tend to persist in some individuals, and these individuals are at a greater risk of cognitive deficits in late midlife.

Recurrent depressive symptoms and the incidence of dementia and mild cognitive impairment

OBJECTIVE

A history of depression has been linked to an increased dementia risk. This risk may be particularly high in recurrent depression due to repeated brain insult. We investigated whether there is a dose-dependent relationship between the number of episodes of elevated depressive symptoms (EDS) and the risk for mild cognitive impairment (MCI) and dementia.

METHODS

A total of 1,239 older adults from the Baltimore Longitudinal Study of Aging were followed for a median of 24.7 years. Diagnoses of MCI and dementia were made based on prospective data. Participants completed the Center for Epidemiologic Studies Depression Scale at 1- to 2-year intervals and were considered to have an EDS if their score was > or = 16. Kaplan-Meier survival curves, log-rank test for trend for survivor functions, and Cox proportional hazards models were conducted to examine the risk of MCI and dementia by number of EDS.

RESULTS

We observed a monotonic increase in risk for all-cause dementia and Alzheimer disease as a function of the number of EDS. Each episode was associated with a 14% increase in risk for all-cause dementia. Having 1 EDS conferred an 87%-92% increase in dementia risk, while having 2 or more episodes nearly doubled the risk. Recurrence of EDS did not increase the risk of incident MCI.

CONCLUSIONS

Our findings support the hypothesis that depression is a risk factor for dementia and suggest that recurrent depression is particularly pernicious. Preventing the recurrence of depression in older adults may prevent or delay the onset of dementia.

Depressive symptoms and risk of dementia: the Framingham Heart Study

OBJECTIVES

Depression may be associated with an increased risk for dementia, although results from population-based samples have been inconsistent. We examined the association between depressive symptoms and incident dementia over a 17-year follow-up period.

METHODS

In 949 Framingham original cohort participants (63.6% women, mean age = 79), depressive symptoms were assessed at baseline (1990-1994) using the 60-point Center for Epidemiologic Studies Depression Scale (CES-D). A cutpoint of > or = 16 was used to define depression, which was present in 13.2% of the sample. Cox proportional hazards models adjusting for age, sex, education, homocysteine, and APOE epsilon4 examined the association between baseline depressive symptoms and the risk of dementia and Alzheimer disease (AD).

RESULTS

During the 17-year follow-up period, 164 participants developed dementia; 136 of these cases were AD. A total of 21.6% of participants who were depressed at baseline developed dementia compared with 16.6% of those who were not depressed. Depressed participants (CES-D >/=16) had more than a 50% increased risk for dementia (hazard ratio [HR] 1.72, 95% confidence interval [CI] 1.04-2.84, p = 0.035) and AD (HR 1.76, 95% CI 1.03-3.01, p = 0.039). Results were similar when we included subjects taking antidepressant medications as depressed. For each 10-point increase on the CES-D, there was significant increase in the risk of dementia (HR 1.46, 95% CI 1.18-1.79, p < 0.001) and AD (HR 1.39, 95% CI 1.11-1.75, p = 0.005). Results were similar when we excluded persons with possible mild cognitive impairment.

CONCLUSIONS

Depression is associated with an increased risk of dementia and AD in older men and women over 17 years of follow-up.

Apolipoprotein e4 genotype and depressive symptoms as risk factors for dementia in an older korean population

OBJECTIVE

Growing evidence suggests the separate associations of apolipoprotein E e4 allele (apo E4) and depression with incident dementia. This study investigated the separate and combined effects of apo E4 and depression on the incidence of dementia in both men and women.

METHODS

Of 625 elderly without dementia at baseline, 518 (83%) were followed over a 2.4-year period and were assessed clinically for incident dementia. The apo E polymorphism was ascertained, and depression was identified using the Korean version of the Geriatric Depression Scale (KGDS). Covariates included age, gender, education, disability, alcohol history, physical activity, and vascular risk factors.

RESULTS

The incidence of dementia was significantly higher in elderly Koreans with both apo E4 and depression compared to those without both factors [adjusted odds ratio (95% CI)=5.85 (1.77-19.38)]. This interaction was significant in men (p=0.049), but not in women (p=0.354).

CONCLUSION

Depressed elderly people are at great risk for incident dementia in the presence of apo E4. Potential gender differences require further evaluation.

Soluble beta amyloid(1-42): a critical player in producing behavioural and biochemical changes evoking depressive-related state?

BACKGROUND AND PURPOSE

Depression is common in early phases of Alzheimer's disease (AD) and may represent prodromal symptoms of dementia. Recent reports suggest that early memory deficits and neuropsychiatric symptoms are caused by soluble rather than aggregated betaamyloid (Abeta). Thus, we investigated the effects of soluble Abeta(1-42) on working memory and depressive/anxiety-related behaviour in rats and on 5-hydroxytryptaminergic neurotransmission and neurotrophin content in various brain regions.

EXPERIMENTAL APPROACH

Behavioural reactivity to novel object recognition, open field, elevated plus maze and forced swimming test were assessed 7 days after i.c.v. injection of Abeta(1-42) or its vehicle. BDNF (brain-derived neurotrophic factor) and NGF (nerve growth factor) mRNA and protein levels and 5-hydroxytriptamine (5-HT) content were measured in the prefrontal cortex (PFC), striatum (STR) and nucleus accumbens (NAc).

KEY RESULTS

Abeta(1-42) did not affect the ability to distinguish between familiar and novel objects, but Abeta-treated rats exhibited an increase in forced swimming immobility. No differences were revealed between experimental groups in the elevated plus maze test or in self-grooming (evaluated in the open field). In the PFC, but not STR or NAc, Abeta-injected rats exhibited a selective reduction in 5-HT content, BDNF and NGF expression.

CONCLUSIONS AND IMPLICATIONS

Our data suggest that soluble Abeta-treated rats have a depressive, but not anxiogenic-like, profile, accompanied by brain region-dependent alterations in the expression of neurotrophins and 5-hydroxytryptaminergic neurotransmission. Hence, these alterations induced by soluble Abeta might be sensitive indicators of early phases of AD and possible risk factors for the expression of neuropsychiatric symptoms in AD.

Depression and plasma amyloid beta peptides in the elderly with and without the apolipoprotein E4 allele

Depression associated with low plasma amyloid-beta peptide 42 (Abeta42) leading to a high ratio of Abeta40/Abeta42, a biomarker of Alzheimer disease (AD), may represent a unique depression subtype. The relationship between low plasma Abeta42 in depression and the major risk factor of AD, apolipoprotein E4 (ApoE4), is unknown. With the goal of clarifying this relationship, we analyzed 1060 homebound elders with ApoE characterization and depression status in a cross-sectional study. Plasma Abeta40 and Abeta42 were measured, and cognition were evaluated. In the absence of the ApoE4 allele, depressed subjects had lower plasma Abeta42 [median (Q1, Q3): 17.1 (11.6, 27.8) vs. 20.2 (12.9, 32.9) pg/mL, P=0.006], a higher Abeta40/Abeta42 ratio [median (Q1, Q3): 7.1 (4.6, 11.3) vs. 6.9 (3.4, 9.7), P=0.03], and lower cognitive function (mean+/-SD of Mini-Mental State Examination: 24.5+/-3.1 vs. 25.5+/-3.3, P<0.0001) than those without depression. In contrast, these relationships were not observed in the presence of ApoE4. Instead, regardless the depression status ApoE4 carriers had lower plasma Abeta42 and a higher Abeta40/Abeta42 ratio than non-ApoE4 carriers. Using multivariate logistic regression, it was found that depression was not associated with ApoE4 allele, but with the interaction between plasma Abeta42 and ApoE4 (odds ratio=3.94, 95% confidence interval=1.50, 10.33, P=0.005), denoting low plasma Abeta42 in the absence of ApoE4. Both ApoE4 carriers and non-ApoE4 carriers with depression had lower Abeta42 and a higher Abeta40/Abeta42 ratio in plasma compared with non-ApoE4 carriers without depression in the homebound elderly. As a combination of low plasma Abeta42 and high plasma Abeta40 has been shown to increase the risk of AD in 2 large cohort studies, amyloid-associated depression shown in this study may suggest a risk factor of AD in the absence of ApoE4.

Frontal Atrophy and Attention Deficits in Older Adults with a History of Elevated Depressive Symptoms

Studies of older adults with depressive disorders indicate greater cognitive deficits and brain alterations than would be expected for their age. There is some evidence that these findings are present after a single episode of depression, but this work has been cross-sectional in nature. We investigated both cross-sectional and longitudinal associations between a history of elevated depressive symptoms (HDS), frontal lobe volumes, and cognitive performance within the context of normal age-related changes over time in the Baltimore Longitudinal Study of Aging. After controlling for age, HDS was associated with smaller total frontal gray matter volumes and with smaller regional volumes in the cingulate gyrus and orbitofrontal cortex. Men, but not women, with HDS showed deficits in auditory attention span at older ages. Results confirm previous reports that even a single episode of depression is associated with adverse outcomes in older adults but suggest that HDS does not affect longitudinal trajectories of cognitive and brain volume change.

Epidemiology of Alzheimer's disease: occurrence, determinants, and strategies toward intervention

More than 25 million people in the world today are affected by dementia, most suffering from Alzheimer's disease. In both developed and developing nations, Alzheimer's disease has had tremendous impact on the affected individuals, caregivers, and society. The etiological factors, other than older age and genetic susceptibility, remain to be determined. Nevertheless, increasing evidence strongly points to the potential risk roles of vascular risk factors and disorders (eg, cigarette smoking, midlife high blood pressure and obesity, diabetes, and cerebrovascular lesions) and the possible beneficial roles of psychosocial factors (eg, high education, active social engagement, physical exercise, and mentally stimulating activity) in the pathogenetic process and clinical manifestation of the dementing disorders. The long-term multidomain interventions toward the optimal control of multiple vascular risk factors and the maintenance of socially integrated lifestyles and mentally stimulating activities are expected to reduce the risk or postpone the clinical onset of dementia, including Alzheimer's disease.

Longitudinal study of chronic depressive symptoms and regional cerebral blood flow in older men and women

OBJECTIVES

Late-life depression is associated with alterations in regional cerebral blood flow (rCBF) and metabolism in a neural network that includes frontostriatal and limbic regions and the cerebellum. Prior studies suggest that clinical depression and subthreshold depressive symptoms (SDS) are associated with similar cognitive deficits and structural brain changes, but little is known about the relationship between SDS and patterns of brain activity. Additionally, the neural correlates of depression have not been fully explored in men and women separately. This study investigated cross-sectional and longitudinal relationships between SDS and rCBF in older men and women.

METHODS

Sixty-one dementia-free older adults (35 men, 26 women), 56 years of age and older at baseline, from the neuroimaging substudy of the Baltimore Longitudinal Study of Aging participated. Participants underwent resting-state PET scans at baseline and at year 9 and completed the Center for Epidemiologic Studies Depression Scale annually.

RESULTS

At 8-year follow-up, both men and women showed cross-sectional associations between mean depressive symptom scores and activity in primarily frontal and temporal regions and the cerebellum. Higher average depressive symptoms were associated with longitudinal rCBF decreases in frontal regions in both men and women, and in temporal regions in men.

CONCLUSION

Regions showing associations between activity and SDS were similar to those found in studies of clinical depression, providing support for the hypothesis that depressive syndromes exist on a continuum of severity. Sex differences in associations provide some evidence that the pathophysiology of depressive disorders differs between men and women.

Effects of the LHRH antagonist Cetrorelix on the brain function in mice

The decapeptide Cetrorelix, an LHRH antagonist, inhibits gonadotropin and sex steroid secretion. Cetrorelix is used for IVF-ET procedures and for the treatment of patients with prostate carcinoma, benign prostatic hyperplasia, endometriosis, leiomyomas and, ovarian cancer. However little is known about the effects of Cetrorelix on the brain function. In the present work the influence of Cetrorelix on different aspects of the brain function was studied following its administration into the lateral brain ventricle in mice. The effects tested included the impairment of the consolidation of a passive avoidance reflex caused by beta-amyloid 25-35, anxiolytic action in the plus-maze, antidepressive action in a forced swimming test and a tail suspension test and open-field behavior. In the passive avoidance test, beta-amyloid 25-35 administered immediately after the learning trial impaired the consolidation of passive avoidance learning. Cetrorelix fully blocked the impairment of the consolidation of passive avoidance learning when given icv 30 min following beta-amyloid 25-35 administration. If beta-amyloid 25-35 and Cetrorelix icv were given simultaneously, the Cetrorelix attenuated, but did not block the action of the beta-amyloid 25-35. Cetrorelix elicited anxiolytic action in the plus-maze, depending on the dose used. In the forced swimming and tail suspension tests, Cetrorelix demonstrated antidepressive-like action. Concerning open-field behavior, Cetrorelix displayed no action on locomotion, rearing or grooming. The results demonstrate that Cetrorelix affects brain function: and is able to correct the impairment of the memory consolidation caused by beta-amyloid 25-35. Cetrorelix also elicits anxiolytic and antidepressive action, but it does not influence the open-field activity. Further experimental work with Cetrorelix is necessary, but the results imply the possible merit of a clinical trial with Cetrorelix in patients with anxiety, depression and Alzheimer's disease.

No association between APOE and major depressive disorder in a community sample of 17,507 adults

Mood-related phenotypes are commonly comorbid with, and have been implicated in the development of, neurological disorders. APOE is a major susceptibility gene for neurodegeneration. Recent evidence from case-control studies has suggested that the apoE 2 allele is associated with major depressive disorder (MDD). However, evidence from large-scale community-based studies is limited. APOE was genotyped for 17,507 men and women, aged 41-80 years, participating in the European Prospective Investigation into Cancer-Norfolk study, who had also completed a psychosocial assessment that included measures of emotional health status defined by MDD, psychological distress (as represented by the Mental Health Inventory, MHI-5), and by an assessment of neuroticism. No associations were found between APOE genotypes and measures either of past-year or lifetime MDD, or of emotional health defined according to the MHI-5 or by neuroticism. Data from this large-scale, community-based, study are not supportive of an association between either MDD or associated measures of emotional state and APOE genotype. These findings suggest that the association between APOE and MDD risk is more modest than has been previously reported.

Enrichment Effects on Adult Cognitive Development: Can the Functional Capacity of Older Adults Be Preserved and Enhanced?

In this monograph, we ask whether various kinds of intellectual, physical, and social activities produce cognitive enrichment effects-that is, whether they improve cognitive performance at different points of the adult life span, with a particular emphasis on old age. We begin with a theoretical framework that emphasizes the potential of behavior to influence levels of cognitive functioning. According to this framework, the undeniable presence of age-related decline in cognition does not invalidate the view that behavior can enhance cognitive functioning. Instead, the course of normal aging shapes a zone of possible functioning, which reflects person-specific endowments and age-related constraints. Individuals influence whether they function in the higher or lower ranges of this zone by engaging in or refraining from beneficial intellectual, physical, and social activities. From this point of view, the potential for positive change, or plasticity, is maintained in adult cognition. It is an argument that is supported by newer research in neuroscience showing neural plasticity in various aspects of central nervous system functioning, neurochemistry, and architecture. This view of human potential contrasts with static conceptions of cognition in old age, according to which decline in abilities is fixed and individuals cannot slow its course. Furthermore, any understanding of cognition as it occurs in everyday life must make a distinction between basic cognitive mechanisms and skills (such as working-memory capacity) and the functional use of cognition to achieve goals in specific situations. In practice, knowledge and expertise are critical for effective functioning, and the available evidence suggests that older adults effectively employ specific knowledge and expertise and can gain new knowledge when it is required. We conclude that, on balance, the available evidence favors the hypothesis that maintaining an intellectually engaged and physically active lifestyle promotes successful cognitive aging. First, cognitive-training studies have demonstrated that older adults can improve cognitive functioning when provided with intensive training in strategies that promote thinking and remembering. The early training literature suggested little transfer of function from specifically trained skills to new cognitive tasks; learning was highly specific to the cognitive processes targeted by training. Recently, however, a new generation of studies suggests that providing structured experience in situations demanding executive coordination of skills-such as complex video games, task-switching paradigms, and divided attention tasks-train strategic control over cognition that does show transfer to different task environments. These studies suggest that there is considerable reserve potential in older adults' cognition that can be enhanced through training. Second, a considerable number of studies indicate that maintaining a lifestyle that is intellectually stimulating predicts better maintenance of cognitive skills and is associated with a reduced risk of developing Alzheimer's disease in late life. Our review focuses on longitudinal evidence of a connection between an active lifestyle and enhanced cognition, because such evidence admits fewer rival explanations of observed effects (or lack of effects) than does cross-sectional evidence. The longitudinal evidence consistently shows that engaging in intellectually stimulating activities is associated with better cognitive functioning at later points in time. Other studies show that meaningful social engagement is also predictive of better maintenance of cognitive functioning in old age. These longitudinal findings are also open to important rival explanations, but overall, the available evidence suggests that activities can postpone decline, attenuate decline, or provide prosthetic benefit in the face of normative cognitive decline, while at the same time indicating that late-life cognitive changes can result in curtailment of activities. Given the complexity of the dynamic reciprocal relationships between stimulating activities and cognitive function in old age, additional research will be needed to address the extent to which observed effects validate a causal influence of an intellectually engaged lifestyle on cognition. Nevertheless, the hypothesis that an active lifestyle that requires cognitive effort has long-term benefits for older adults' cognition is at least consistent with the available data. Furthermore, new intervention research that involves multimodal interventions focusing on goal-directed action requiring cognition (such as reading to children) and social interaction will help to address whether an active lifestyle enhances cognitive function. Third, there is a parallel literature suggesting that physical activity, and aerobic exercise in particular, enhances older adults' cognitive function. Unlike the literature on an active lifestyle, there is already an impressive array of work with humans and animal populations showing that exercise interventions have substantial benefits for cognitive function, particularly for aspects of fluid intelligence and executive function. Recent neuroscience research on this topic indicates that exercise has substantial effects on brain morphology and function, representing a plausible brain substrate for the observed effects of aerobic exercise and other activities on cognition. Our review identifies a number of areas where additional research is needed to address critical questions. For example, there is considerable epidemiological evidence that stress and chronic psychological distress are negatively associated with changes in cognition. In contrast, less is known about how positive attributes, such as self-efficacy, a sense of control, and a sense of meaning in life, might contribute to preservation of cognitive function in old age. It is well known that certain personality characteristics such as conscientiousness predict adherence to an exercise regimen, but we do not know whether these attributes are also relevant to predicting maintenance of cognitive function or effective compensation for cognitive decline when it occurs. Likewise, more information is needed on the factors that encourage maintenance of an active lifestyle in old age in the face of elevated risk for physiological decline, mechanical wear and tear on the body, and incidence of diseases with disabling consequences, and whether efforts to maintain an active lifestyle are associated with successful aging, both in terms of cognitive function and psychological and emotional well-being. We also discuss briefly some interesting issues for society and public policy regarding cognitive-enrichment effects. For example, should efforts to enhance cognitive function be included as part of a general prevention model for enhancing health and vitality in old age? We also comment on the recent trend of business marketing interventions claimed to build brain power and prevent age-related cognitive decline, and the desirability of direct research evidence to back claims of effectiveness for specific products.

Apolipoprotein E epsilon4 allele genotype and the effect of depressive symptoms on the risk of dementia in men: the Honolulu-Asia Aging Study

CONTEXT

The apolipoprotein E epsilon4 (APOE epsilon4) allele is a genetic risk factor for Alzheimer disease. Recently, depression has also become recognized as a risk factor for dementia. However, the possible effect of the APOE genotype on the association between depression and dementia is unexamined.

OBJECTIVE

To examine the independent and combined effects of depression and APOE epsilon4 on the risk of dementia and its subtypes.

DESIGN

The Honolulu-Asia Aging Study, a population-based prospective cohort study of Japanese American men.

SETTINGS AND PARTICIPANTS

Depressive symptoms and presence of the APOE epsilon4 allele were assessed between March 1991 and October 1993 in 1932 cognitively healthy men aged 71 to 90 years. Incident cases of dementia were diagnosed during approximately 6 years of follow-up based on neurologic assessment at 2 repeated examinations (April 1994-April 1996 and October 1997-February 1999).

MAIN OUTCOME MEASURES

Overall dementia, Alzheimer disease, and vascular dementia.

RESULTS

The interaction of depression and APOE epsilon4 was statistically significant in the analytical models. Compared with men with neither APOE epsilon4 nor depression, the risk of dementia in nondepressed men with APOE epsilon4 was not significant (hazard ratio, 1.1; 95% confidence interval [CI], 0.6-1.8); however, depressed men without APOE epsilon4 had a 1.6-fold greater risk (95% CI, 0.8-3.0), whereas depressed men with APOE epsilon4 had a 7.1-fold greater risk (95% CI, 3.0-16.7) of dementia. For subtypes, we found similar increased risks of Alzheimer disease.

CONCLUSIONS

The APOE epsilon4 status modifies the association between depressive symptoms and dementia in elderly men. Because individuals with depressive symptoms and the APOE epsilon4 allele had a markedly increased risk of dementia, one might be especially watchful for early signs of dementia in the older person with depression who is also positive for the APOE epsilon4 allele. Because this cohort includes only men, further investigation in women is required.

Association between BDNF Val66Met polymorphism and trait depression is mediated via resting EEG alpha band activity

A functional polymorphism of the brain-derived neurotrophic factor, BDNF Val66Met, is associated with risk for major depression alongside impairments in memory and selective attention. This study aims to identify the mediating neural mechanisms in links between BDNF and depression using highly heritable electroencephalographic (EEG) recordings. In 305 healthy subjects, BDNF Val66Met genotypes were compared in terms of trait depression, neural function (EEG during a resting state) and cognitive performance. The mediating effects of the EEG brain imaging endophenotypes were also examined using structural equation (path) modeling. A genotype-endophenotype-phenotype path model showed that Met homozygosity predicted elevated working memory commission errors and altered EEG activity; that is elevated relative theta and delta power coupled with reduced alpha power. In turn, reduced EEG alpha activity mediated the relationship between the Met/Met genotype and trait depression. These findings demonstrate the utility of an integrative endophenotype approach. They suggest that the BDNF Met/Met homozygote has a direct impact on memory systems, but impacts trait depression via the secondary effects of neural changes.

Impact of depressive symptoms on the rate of progression to dementia in patients affected by mild cognitive impairment. The Italian Longitudinal Study on Aging

BACKGROUND

Mild cognitive impairment (MCI) is often a prodromal of dementia and depressive symptoms have been suggested as risk factor for dementing disorders. We evaluated the possible impact of depressive symptoms on the rate of progression to dementia in MCI patients after a 3.5-year follow-up; and the interaction between depressive symptoms and vascular risk factors for conversion to dementia.

METHODS

A total of 2,963 individuals from a sample of 5,632 65-84 year old subjects were evaluated at the first (1992-1993), and second survey (1995-1996) of the Italian Longitudinal Study on Aging (ILSA), a prospective cohort study. MCI and dementia were classified using current clinical criteria. Depressive symptoms were measured with the Geriatric Depression Scale.

RESULTS

Among the 2,963 participants, 139 prevalent MCI patients were diagnosed at the first survey. During the 3.5-year follow-up, 14 MCI patients progressed to dementia, and we did not find any significant relationship between depressive symptoms and rate of progression to dementia (RR 1.42, 95% CI, 0.48-4.23, chi2 0.40, p < 0.53). No socio-demographic variables or vascular risk factors modified the association between depressive symptoms and conversion to dementia.

CONCLUSIONS

In our population, depressive symptoms were not associated with the rate of progression to dementia in MCI patients. Our findings did not support a role of socio-demographic variables or vascular risk factors in the association of depressive symptoms and conversion to dementia.

The Worldwide Challenge of the Dementias: A Role for B Vitamins and Homocysteine?

Dementia has reached epidemic proportions, with an estimated 4.6 million new cases worldwide each year. With an aging world population, the prevalence of dementia will increase dramatically in the next few decades. Of the predicted 114 million who will have dementia in 2050, about three-quarters will live in less developed regions. Although strongly age-related, dementia is not an inevitable part of aging but is a true disease, caused by exposure to several genetic and nongenetic risk factors. Prevention will be possible when the nongenetic risk factors have been identified. Apart from age, more than 20 nongenetic risk factors have been postulated, but very few have been established by randomized intervention studies. Elevated blood concentrations of total homocysteine and low-normal concentrations of B vitamins (folate, vitamin B12, and vitamin B6) are candidate risk factors for both Alzheimer's disease and vascular dementia. Seventy-seven cross-sectional studies on more than 34,000 subjects and 33 prospective studies on more than 12,000 subjects have shown associations between cognitive deficit or dementia and homocysteine and/or B vitamins. Biologically plausible mechanisms have been proposed to account for these associations, including atrophy of the cerebral cortex, but a definite causal pathway has yet to be shown. Raised plasma total homocysteine is a strong prognostic marker of future cognitive decline, and is common in world populations. Low-normal concentrations of the B vitamins, the main determinant of homocysteine concentrations, are also common and occur in particularly vulnerable sections of the population, such as infants and elderly. Large-scale randomized trials of homocysteine-lowering vitamins are needed to see if a proportion of dementia in the world can be prevented.

Depressive symptoms, vascular risk factors and mild cognitive impairment. The Italian longitudinal study on aging

AIMS

We evaluated the impact of depressive symptoms on the rate of incident mild cognitive impairment (MCI) after a 3.5-year follow-up, and we assessed the interaction between depressive symptoms and vascular risk factors for incident MCI.

METHODS

A total of 2,963 individuals from a sample of 5,632 65- to 84-year-old subjects were cognitively and functionally evaluated at the 1st and 2nd surveys of the Italian Longitudinal Study on Aging, a prospective cohort study with a 3.5-year follow-up. MCI and dementia were classified using current clinical criteria. Depressive symptoms were measured with the Geriatric Depression Scale.

RESULTS

Among the 2,963 participants, 139 prevalent MCI cases were diagnosed at the 1st survey. During the 3.5-year follow-up, 105 new events of MCI were diagnosed. We did not observe any significant association between depressive symptoms and incident MCI (RR = 1.25, 95% CI = 0.85-1.84, chi(2) = 1.30, p < 0.25). No sociodemographic variables or vascular risk factors modified the relationship between depressive symptoms and incident MCI.

CONCLUSION

In our population, depressive symptoms were not associated with the rate of incident MCI. Our findings did not support a role of sociodemographic variables or vascular risk factors in the link between depressive symptoms and incident MCI.

Amyloid-associated depression: a prodromal depression of Alzheimer disease?

CONTEXT

A high ratio of plasma amyloid-beta peptide 40 (Abeta(40)) to Abeta(42), determined by both high Abeta(40) and low Abeta(42) levels, increases the risk of Alzheimer disease. In a previous study, we reported that depression is also associated with low plasma Abeta(42) levels in the elderly population.

OBJECTIVE

To characterize plasma Abeta(40):Abeta(42) ratio and cognitive function in elderly individuals with and without depression.

DESIGN

Cross-sectional study.

SETTING

Homecare agencies.

PARTICIPANTS

A total of 995 homebound elderly individuals of whom 348 were defined as depressed by a Center for Epidemiological Studies Depression score of 16 or greater.

MAIN OUTCOME MEASURES

Cognitive domains of memory, language, executive, and visuospatial functions according to levels of plasma Abeta(40) and Abeta(42) peptides.

RESULTS

Subjects with depression had lower plasma Abeta(42) levels (median, 14.1 vs 19.2 pg/mL; P = .006) and a higher plasma Abeta(40):Abeta(42) ratio (median, 8.9 vs 6.4; P < .001) than did those without depression in the absence of cardiovascular disease and antidepressant use. The interaction between depression and plasma Abeta(40):Abeta(42) ratio was associated with lower memory score (beta = -1.9, SE = 0.7, P = .006) after adjusting for potentially confounders. Relative to those without depression, "amyloid-associated depression," defined by presence of depression and a high plasma Abeta(40):Abeta(42) ratio, was associated with greater impairment in memory, visuospatial ability, and executive function; in contrast, nonamyloid depression was not associated with memory impairment but with other cognitive disabilities.

CONCLUSION

Amyloid-associated depression may define a subtype of depression representing a prodromal manifestation of Alzheimer disease.

Rates of depression in individuals with pathologic but not clinical Alzheimer disease are lower than those in individuals without the disease: findings from the Baltimore Longitudinal Study on Aging (BLSA)

The prevalence of major depression is increased in Alzheimer disease (AD), but currently the basis of this association remains unclear. The present study examined rates of depression in 4 groups of participants with postmortem examination from the Baltimore Longitudinal Study of Aging: (1) cognitively normal controls with no Alzheimer pathology, (2) cognitively normal individuals with Alzheimer pathology, (3) individuals with mild cognitive impairment plus Alzheimer pathology, (4) individuals with clinical diagnoses of dementia plus Alzheimer pathology. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale. Individuals with Alzheimer pathology but no cognitive decline before death had significantly lower rates of depression than cognitively normal controls with no Alzheimer pathology and individuals with Alzheimer pathology plus clinical diagnoses of dementia. These findings suggest that depression is a risk factor for AD in the presence of AD pathology, but depression is not a risk factor for AD pathology.

Depression, antidepressants, and plasma amyloid beta (Beta) peptides in those elderly who do not have cardiovascular disease

BACKGROUND

Low plasma amyloid-beta peptide 42 (Abeta42) is associated with depressive symptoms independently of cardiovascular disease (CVD) in the elderly. It is critical to investigate whether antidepressants modify this relationship.

METHODS

We evaluated 324 elders without CVD in a cross-sectional study. Depression was evaluated with the Center for Epidemiological Studies Depression (CES-D) scale. Antidepressants were documented. Plasma Abeta40 and Abeta42 were measured.

RESULTS

In the absence of CVD, those with depression had lower plasma Abeta42 (median: 13.7 vs. 18.8 pg/mL, p = .003) than those without. Depressed subjects on antidepressant treatment had a lower concentration of plasma Abeta40 (median: 97.8 vs. 133.5 pg/mL, p = .008), but not Abeta42, than those without the treatment. Multivariate logistic regression showed that antidepressant use did not influence the relationship between depression and low plasma Abeta42 (odds ratio = .55; 95% CI = .33, .90; p = .02) after adjusting for confounders, but its use interacted with plasma Abeta40 in the model.

CONCLUSIONS

Lower concentration of plasma Abeta42 is associated with depression in the absence of CVD that is not related to the antidepressant use by those subjects. Prospective studies are needed to determine whether depression associated with low plasma Abeta42 predicts the onset of Alzheimer's disease.

Symptoms of anxiety and depression in the course of cognitive decline

BACKGROUND/AIMS

Anxiety and depression are common inpatients with cognitive decline and Alzheimer's disease (AD), and recognition and treatment of these symptoms can improve their quality of life. The present study investigates anxiety and depression in different phases of cognitive decline.

METHODS

The sample consisted of five groups of elderly people in different phases of cognitive decline; four from a community-based sample (Longitudinal Aging Study Amsterdam), and one group of elderly people diagnosed with AD. ANOVAs were performed to investigate group differences in the severity and prevalence of anxiety and depression, and comorbid anxiety and depressive symptoms.

RESULTS

The prevalence rates of anxiety, comorbid anxiety and depressive symptoms and depressive symptoms follow a pattern of an increasing prevalence as cognitive performance declines and a decrease in the prevalence when cognitive functioning is severely impaired. AD patients report fewest anxiety symptoms.

CONCLUSION

We found that the prevalence of anxiety symptoms, depressive symptoms and comorbid anxiety and depressive symptoms seems to increase in the early phase of cognitive decline, and decreases as cognitive functioning further declines. Elderly diagnosed with AD report less anxiety as expected, probably due to lack of insight caused by AD.

Subjective memory complaints: presence, severity and future outcome in normal older subjects

BACKGROUND/AIMS

Subjective memory complaint (SMC) in normal individuals may predict future cognitive decline. The goal of this study was to examine whether the probability of decline increases with growing intensity of complaint.

METHODS

Normal subjects over the age of 50 years were included in a longitudinal retrospective study (mean follow-up time = 8 years). All subjects (n = 230) underwent cognitive and medical examination at baseline. The presence of SMC was determined based on Global Deterioration Scale staging. A subgroup of 83 participants also received baseline assessment for the intensity of SMC. Logistic regression was used to predict outcome from baseline variables. Three outcome groups were established at the final visit: nondeclining, declining and diagnostically unstable (i.e. the diagnosis changed over time: from normal to mild cognitive impairment, then back to normal).

RESULTS

The presence of SMC was a predictor of future decline but also increased the likelihood of the unstable diagnosis. Increasing intensity of SMC did not further raise the risk for decline. High intensity of complaints and more pronounced affective symptoms predicted the unstable clinical diagnosis.

CONCLUSIONS

The presence of SMC contributes to the risk of future decline, however, the increasing intensity of the perceived impairment does not further enhance the risk.

Chronic distress and incidence of mild cognitive impairment

OBJECTIVE

Mild cognitive impairment (MCI) is associated with increased morbidity and mortality but its development is not well understood. Here we test the hypothesis that chronic psychological distress is associated with increased incidence of MCI in old age.

METHODS

Participants are older persons from two cohort studies with uniform annual clinical evaluations which included detailed cognitive testing and clinical classification of MCI. We excluded persons with dementia or MCI at baseline; follow-up data were available on 1,256 persons without cognitive impairment (95% of those eligible). At baseline, they completed a six-item measure of neuroticism (mean = 15.6, SD = 6.6), an indicator of the tendency to experience psychological distress.

RESULTS

During up to 12 years of follow-up, 482 persons (38%) developed MCI. Risk of MCI increased by about 2% for each one unit increase on the distress scale (relative risk [RR] = 1.02; 95% CI: 1.01, 1.04), with the association slightly stronger in men than women. Overall, a distress-prone person (score = 24, 90th percentile) was about 40% more likely to develop MCI than someone not prone to distress (score = 8, 10th percentile). Adjustment for depressive symptomatology at baseline did not substantially change results (RR = 1.02; 95% CI: 1.00, 1.03). Depressive symptoms were also related to risk of MCI but not after controlling for distress score. In mixed-effects models, higher distress score was associated with lower level of function in multiple cognitive domains at baseline and more rapid cognitive decline, especially in episodic memory.

CONCLUSION

Among older persons without manifest cognitive impairment, higher level of chronic psychological distress is associated with increased incidence of mild cognitive impairment.

Depression is associated with low plasma Abeta42 independently of cardiovascular disease in the homebound elderly

BACKGROUND

Depression often precedes the onset of Alzheimer's disease (AD) before the appearance of cognitive symptoms. Plasma Amyloid-beta peptide 42 (Abeta42) declines before and soon after the onset of AD, yet the relationship between plasma Abeta42 and depression is unclear.

METHODS

We used 515 homebound elders aged 60 and older in a population-based, cross-sectional study to investigate associations between plasma Abeta levels and depression with and without cardiovascular co-morbidities. Depression was evaluated by using the Center for Epidemiological Studies Depression (CES-D) scale. Plasma Abeta40 and Abeta42 were measured.

RESULTS

The elderly with depression had lower plasma Abeta42 (median: 15.3 vs. 18.9, p = 0.008) than those without depression. The CES-D score was inversely associated with plasma Abeta42 (p = 0.001) in subjects with no cardiovascular disease (CVD); however, in the presence of CVD, this association did not exist. Low plasma Abeta42 (OR = 0.41, p = 0.007) and the presence of CVD (OR = 1.84, p = 0.005) were independently associated with depression after adjusting for the confounders of age, stroke and apolipoprotein E4.

CONCLUSIONS

Depressive symptoms are associated with low plasma Abeta42 independently of CVD. Prospective studies are needed to determine whether depression associated with low plasma Abeta42 is a separate depression subtype that could predict the onset of AD.

Depressive symptoms, major depressive episode and cognition in the elderly: the three-city study

OBJECTIVES

The relationship between depression and dementia in the elderly has been extensively studied but the tools used to define depressed subjects are heterogeneous between studies. The objective of this study was to examine the relationship between depression and cognitive performances by using multiple measures of depressive state.

METHODS

A sample of 7,869 nondemented community-dwelling persons aged >or=65 years participated in the study. Depressive symptoms were evaluated by the Center for Epidemiological Study Depression Scale and the Mini-International Neuropsychiatric Interview was used to assess history of major depressive episodes (MDE). Cognitive function was evaluated by several tests including the Mini-Mental State Examination (MMSE), Trail Making Test, Isaacs Set Test and Benton Visual Retention Test.

RESULTS

When studied in separate models, depressive symptoms were significantly related to lower cognitive performances for all neuropsychological tests after adjusting for potential confounders (p<0.0001), whereas subjects with current MDE had significantly lower performances in MMSE and Isaacs Set Test. When studied concomitantly, only high levels of depressive symptoms were related to lower cognitive performance, whereas existence of MDE (past or current) was no longer associated with cognitive performances.

CONCLUSIONS

These data suggest that once current depressive symptoms are taken into account, major depression (past or current) is not associated with lower cognitive performances in a community-based sample of elderly people aged >or=65 years.

Depression and risk for Alzheimer disease: systematic review, meta-analysis, and metaregression analysis

CONTEXT

A history of depression may increase risk for developing Alzheimer disease (AD) later in life. Clarifying this relation might improve understanding of risk factors for and disease mechanisms in AD.

OBJECTIVE

To systematically review and complete a meta-analysis on the relation of depression and AD.

DATA SOURCES

We conducted electronic bibliographic searches of MEDLINE, PsychLit, EMBASE, and BIOSIS using search terms sensitive to studies of etiology combined with searches on terms related to depression and AD and reviewed reference lists of articles.

STUDY SELECTION

Studies with data contrasting depressed vs nondepressed patients who did and did not later develop AD were included. Studies that related continuous measures of depression and cognitive status were excluded.

DATA EXTRACTION

Numerical data were independently extracted by 3 reviewers. They also rated studies on a scale that assessed quality indicators for observational studies. Data on the interval between observation of depression and the diagnosis of AD were collected when available.

DATA SYNTHESIS

Meta-analytic evaluation with random-effects models resulted in pooled odds ratios of 2.03 (95% confidence interval, 1.73-2.38) for case-control and of 1.90 (95% confidence interval, 1.55-2.33) for cohort studies. Findings of increased risk were robust to sensitivity analyses. Interval between diagnoses of depression and AD was positively related to increased risk of developing AD, suggesting that rather than a prodrome, depression may be a risk factor for AD.

CONCLUSIONS

A history of depression may confer an increased risk for later developing AD. This relation may reflect an independent risk factor for the disease.

Why sex matters for neuroscience

A rapidly burgeoning literature documents copious sex influences on brain anatomy, chemistry and function. This article highlights some of the more intriguing recent discoveries and their implications. Consideration of the effects of sex can help to explain seemingly contradictory findings. Research into sex influences is mandatory to fully understand a host of brain disorders with sex differences in their incidence and/or nature. The striking quantity and diversity of sex-related influences on brain function indicate that the still widespread assumption that sex influences are negligible cannot be justified, and probably retards progress in our field.

Cognitive assessment and differentiating the 3 Ds (dementia, depression, delirium)

Differentiation between a diminished or altered cognitive functioning asa consequence of aging and one resulting from serious health problems is critical in the elderly. An unrecognized cognitive disorder or the worsening of the impairment may hamper the effectiveness and appropriateness of care and treatment; therefore, standardized assessment procedures and systematic monitoring of cognition and behavior are important aspects of the nursing care. of older adults. In this article, current notions for accurate and comprehensive cognitive assessment in older persons are delineated. Further, an overview of epidemiological screening and diagnostic dilemmas of dementia, depression, and deliriumare provided.

Course and outcomes of depression in the elderly

Major depressive disorder is a potentially debilitating condition that often is unrecognized or undertreated in the elderly. Even when aggressively treated, the course of geriatric depression can be severe. There is growing evidence that suggests that late-life depression may carry a higher illness burden than depression with onset earlier in life, and that severity is linked to medical and psychiatric comorbidity. Data continue to accumulate in support of various treatment modalities, including medication, electroconvulsive therapy, and psychotherapy. Given the increased risk of adverse outcomes associated with geriatric depression, such as dementia and suicide, it is essential that future investigations continue to build on the evidence base supporting improved diagnosis and treatment of this complex disorder.

Predicting Alzheimer's disease in the Baltimore longitudinal study of aging

Longitudinal studies offer opportunities for studying children whose parents have Alzheimer's disease. The Baltimore Longitudinal Study of Aging (BLSA) has examined adult cognitive performance but has not systematically recruited participants' children. We initiated studies of dementia in the 1980s. This work suggested that hormone replacement and use of nonsteroidal anti-inflammatory drugs reduced the risk of Alzheimer's disease and that risk for Alzheimer's disease could be predicted from cognitive performance as many as 20 years prior to its onset. More recently, we showed that premorbid levels of free testosterone were lower in men who developed Alzheimer's disease and premorbid depressive symptomatology was a risk for Alzheimer's disease in men but not women as many as 6 years before the onset of dementia. Participants in the BLSA include family members with a variety of degrees of relationship, but there is no systematic effort to collect data from relatives of participants.