Depression in Alzheimer's disease: is there a temporal relationship between the onset of depression and the onset of dementia?

The Interface between Depression and Alzheimer's Disease. A Comprehensive Approach

Depression and Alzheimer's disease (AD) are frequent interacting diseases in the elderly with a negative impact on the quality of life of patients and caregivers. Late-life depression may be regarded either as an early symptom of AD or a risk factor for AD, depending on the context. This review was focused on the latest developments in the fields of the neurobiological basis and treatment of depression in AD. We found that some plausible hypotheses are emerging to correlate with depression in AD, such as neuroinflammation and dysimmune regulation. It seems that depression is not related to amyloid deposition, but this issue is not completely resolved. The response to antidepressants is controversial according to the evidence from 10 small double-blind randomized placebo-controlled clinical trials with antidepressants in AD patients with depression: four with sertraline, one with three arms (sertraline, mirtazapine, placebo), one with fluoxetine, one with imipramine, one with clomipramine, one with escitalopram, and one with vortioxetine. The total number of treated patients completing the trials was 638. The main criterion of a positive response was a reduction in the scores of clinical scales for depression of at least 50%. The weighted OR (odds ratio) was calculated with the method of Mantel-Haenszel: 1.29; 95% CI: 0.77-2.16. No significant differences were found compared with placebo. Antidepressants did not have a meaningful negative influence on cognition, which was measured with the mini-mental state examination (MMSE) in 18 clinical trials. Alternatives other than drugs are also discussed. Although there have been important advances in this field, pathophysiology and treatment deserve further research.

Age-Dependent Alterations in Platelet Mitochondrial Respiration

Mitochondrial dysfunction is an important cellular hallmark of aging and neurodegeneration. Platelets are a useful model to study the systemic manifestations of mitochondrial dysfunction. To evaluate the age dependence of mitochondrial parameters, citrate synthase activity, respiratory chain complex activity, and oxygen consumption kinetics were assessed. The effect of cognitive impairment was examined by comparing the age dependence of mitochondrial parameters in healthy individuals and those with neuropsychiatric disease. The study found a significant negative slope of age-dependence for both the activity of individual mitochondrial enzymes (citrate synthase and complex II) and parameters of mitochondrial respiration in intact platelets (routine respiration, maximum capacity of electron transport system, and respiratory rate after complex I inhibition). However, there was no significant difference in the age-related changes of mitochondrial parameters between individuals with and without cognitive impairment. These findings highlight the potential of measuring mitochondrial respiration in intact platelets as a means to assess age-related mitochondrial dysfunction. The results indicate that drugs and interventions targeting mitochondrial respiration may have the potential to slow down or eliminate certain aging and neurodegenerative processes. Mitochondrial respiration in platelets holds promise as a biomarker of aging, irrespective of the degree of cognitive impairment.

Anxiety and depression in Alzheimer's disease: a systematic review of pathogenetic mechanisms and relation to cognitive decline

Objectives

To explore the pathogenetic hypothesis provided to explain the comorbidity of anxious and depressive symptomatology and AD and to assess the association between anxious and depressive symptoms and the AD-related cognitive impairment.

Methods

In October 2020 and March 2021, PsycINFO, Embase, Ovid, and CINAHL were searched for peer-reviewed original articles investigating anxiety and/or depression in AD.

Results

A total of 14,760 studies were identified and 34 papers on AD patients were included in the review. Suggested biological causes of depression and anxiety in AD include higher strychnine-sensitive glycine receptor (GlyRS) functioning and selective reduction of N-methyl-d-aspartate (NMDA) receptor NR2A density, cortical and limbic atrophy, lower resting cortical metabolism, lower CSF Aβ42 and higher t-tau and p-tau levels, and neuritic plaques. At the same time, dysthymia arises in the early stages of AD as an emotional reaction to the progressive cognitive decline and can cause it; anxiety can appear as an initial compensating behaviour; and depression might be related to AD awareness and loss of functional abilities. Affective symptoms and the expression of the depressive symptoms tend to reduce as AD progresses.

Conclusion

The neurodegeneration of areas and circuits dealing with emotions can elicit anxiety and depression in AD. In the early stages of the disease, anxiety and depression could arise as a psychological reaction to AD and due to coping difficulties. In late AD stages, the cognitive impairment reduces the emotional responses and their expression. Anxiety and depression are more intense in early-onset AD, due to the major impact of AD on the individual.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10072-022-06068-x.

Stress-Induced Depression and Alzheimer's Disease: Focus on Astrocytes

Neurodegenerative diseases and depression are multifactorial disorders with a complex and poorly understood physiopathology. Astrocytes play a key role in the functioning of neurons in norm and pathology. Stress is an important factor for the development of brain disorders. Here, we review data on the effects of stress on astrocyte function and evidence of the involvement of astrocyte dysfunction in depression and Alzheimer's disease (AD). Stressful life events are an important risk factor for depression; meanwhile, depression is an important risk factor for AD. Clinical data indicate atrophic changes in the same areas of the brain, the hippocampus and prefrontal cortex (PFC), in both pathologies. These brain regions play a key role in regulating the stress response and are most vulnerable to the action of glucocorticoids. PFC astrocytes are critically involved in the development of depression. Stress alters astrocyte function and can result in pyroptotic death of not only neurons, but also astrocytes. BDNF-TrkB system not only plays a key role in depression and in normalizing the stress response, but also appears to be an important factor in the functioning of astrocytes. Astrocytes, being a target for stress and glucocorticoids, are a promising target for the treatment of stress-dependent depression and AD.

Spousal caregiving, widowhood, and cognition: A systematic review and a biopsychosocial framework for understanding the relationship between interpersonal losses and dementia risk in older adulthood

Accumulating research suggests that stressful life events, especially those that threaten close intimate bonds, are associated with an increased risk of dementia. Grieving the loss of a spouse, whether in the form of caregiving or after the death, ranks among 'life's most significant stressors', evoking intense psychological and physiological distress. Despite numerous studies reporting elevated dementia risk or poorer cognition among spousal caregivers and widow(er)s compared to controls, no review has summarized findings across cognitive outcomes (i.e., dementia incidence, cognitive impairment rates, cognitive performance) or proposed a theoretical model for understanding the links between partner loss and abnormal cognitive decline. The current systematic review summarizes findings across 64 empirical studies. Overall, both cross-sectional and longitudinal studies revealed an adverse association between partner loss and cognitive outcomes. In turn, we propose a biopsychosocial model of cognitive decline that explains how caregiving and bereavement may position some to develop cognitive impairment or Alzheimer's disease and related dementias. More longitudinal studies that focus on the biopsychosocial context of caregivers and widow(er)s are needed.

Different Sides of Depression in the Elderly: An In-depth View on the Role of Aβ Peptides

BACKGROUND

Late-onset depression (LOD) is the most common neuropsychiatric disorder associated with Alzheimer's disease (AD), often associated with structural and functional brain changes, neuropsychological impairments and negative family history for affective disorders. LOD could be a risk factor or a prodromal phase of AD; this has led to the investigation of the link between depression and amyloid-β (Aβ) peptides by measuring Aβ levels in plasma, cerebrospinal fluid (CSF) and brains of elderly depressed subjects.

OBJECTIVE

Clarify the complex relationship between depression, Aβ peptides and AD.

METHOD

We evaluated all articles published up to 2019 in PubMed in which Aβ was measured in serum (or plasma), CSF or brain in elderly with Major Depressive Disorder or depressive symptoms evaluated with standard scales.

RESULTS

Low plasma Aβ42 levels are strongly associated with depression severity. Plasma Aβ40 levels are higher in younger depressed, drug-resistant and those with more severe symptoms. CSF Aβ42 levels are lower in depressed than controls. PET-detected global and region-specific increases in Aβ deposition are sometimes associated with LOD, cognitive impairment, anxiety but not with Cardiovascular Diseases (CVDs)/CVD risk factors. Elderly depressed with CVDs/CVD risk factors have more frequently high plasma Aβ40 levels and drug-resistance; those without these co-morbidities have low plasma Aβ42 levels and a greater cognitive impairment.

CONCLUSION

Two specific Aβ profiles emerge in elderly depressed. One is associated with Aβ42 reductions in plasma and CSF, possibly reflecting increased brain amyloid deposition and prodromal AD. The other one is characterized by high plasma Aβ40 levels, cerebrovascular disease and clinically associated with increased AD risk.

Chronic Stress and Oxidative Stress as Common Factors of the Pathogenesis of Depression and Alzheimer's Disease: The Role of Antioxidants in Prevention and Treatment

There is a growing body of scientific research showing the link between depression and dementia in Alzheimer’s disease (AD). The chronic stress contributes to the formation of oxidative stress in the parts of the brain involved in the development of depression and AD. The scientific literature reports the significant role of antioxidants, which are highly effective in treating these diseases. In this review, we have summarized the relationship between chronic stress, oxidative stress, and the changes in the brain they cause occurring in the brain. Among all the compounds showing antioxidant properties, the most promising results in AD treatment were observed for Vitamin E, coenzyme Q10 (CoQ10), melatonin, polyphenols, curcumin, and selenium. In case of depression treatment, the greatest potential was observed in curcumin, zinc, selenium, vitamin E, and saffron.

Ethnic Differences in Loneliness, Depression, and Malnutrition Among Older Adults During COVID-19 Quarantine

BACKGROUND

Depression in older adults may result from a variety of reasons such as loneliness feelings and malnutrition.

OBJECTIVE

To examine the direct and indirect effect of loneliness feelings on depressive symptoms, mediated by malnutrition, among older adults from different cultures during the Coronavirus disease 2019 (Covid-19) pandemic quarantine.

METHOD

A convenience sample of 101 Arabs and 100 Jewish older adults aged 65 and over was interviewed. Using bootstrapping, we tested the strength and significance of the conditional indirect effect of malnutrition (mediator) on the relationship between loneliness feelings and depressive symptoms.

RESULTS

The relationship between loneliness feelings and depressive symptoms was mediated by malnutrition and Arab older adults reported a higher level than Jewish older adults of loneliness, depression, and malnutrition during the Covid-19 pandemic quarantine.

CONCLUSIONS AND IMPLICATIONS

To reduce loneliness feelings, depressive symptoms, and malnutrition in times of crisis like the Covid-19 pandemic, it is essential to develop new communication methods for and with older adults in general, with particular attention paid to ethnic differences, that will be effective in reducing loneliness and in promoting nutrition intervention. Possible solutions include new social network technologies for reducing loneliness, with continued reliance on phone communication for combined intervention that includes psychological support accompanied by instructions for a healthy lifestyle and malnutrition prevention.

Use of radiomic features and support vector machine to discriminate subjective cognitive decline and healthy controls

Subjective cognitive decline (SCD) is a high-risk preclinical stage in the progress of Alzheimer's disease (AD). Its timely diagnosis is of great significance for older adults. Though multi-parameter magnetic resonance imaging (MPMRI) is a noninvasive neuroimaging technique to detect SCD, the lack of biomarkers and computed aided diagnosis (CAD) tools is a major concern for its application. Radiomics, a high-dimensional imaging feature extraction method, has been widely used for identifying biomarkers and developing CAD tools in oncological studies. Therefore, in this study, we aimed to investigate whether the radiomic approach could be used for the diagnosis of SCD. In the proposed radiomic approach, we mainly performed four steps: image preprocessing, feature extraction and screening, and classification. The dataset from Xuanwu Hospital, Beijing, China, was used in this study, including 105 healthy controls (HC) and 130 SCD subjects. All subjects were divided into one training & validation group and one test group. We extracted 30128 radiomic features from MPMRI of each subject. The t-test, autocorrelation, and Fisher score were performed for feature selection, and we deployed the support vector machine (SVM) for classification. The above process was performed 100 times with 5-fold cross-validation. The results showed that the accuracy, sensitivity, and specificity of classification was 89.03%±5.37%, 85.44%±9.28% and 91.97%±6.38% in the validation set and 84.70%±4.68%, 86.98%±10.49% and 82.59%±7.07% in the test set. In conclusion, this study has shown that the radiomic approach could be used to discriminate SCD and HC with high accuracy and sensitivity effectively.

Pattern of inpatient care for depression: an analysis of 232,289 admissions

BACKGROUND

The prevalence of major depressive disorder (MDD) in women is up to 50% higher as compared to men. However, little is known about discrepancies in health care utilization between depressed female and male patients. Consequently, the aim of the present study was to elucidate gender differences regarding the frequency of hospital admissions and the length of inpatient treatment for MDD across the lifespan.

METHODS

This nationwide, registry-based study analyzed all inpatient admissions in psychiatric hospitals due to recurrent/non-recurrent MDD episodes according to ICD-10 (moderate (F32/33.1), severe (F32/33.2), severe with psychotic features (F32/33.3)) in Austria across 14 years. We calculated weekly admission rates per 100,000 patients by directly age-standardized rates.

RESULTS

Across 232,289 admissions (63.2% female) the population based admission rates in MDD were significantly higher in women (p < 0.001). Female to male ratios across subgroups were 1.65 (F32/33.1), 1.58 (F32/33.2), 1.73 (F32/33.3), and peaked around 65 years (ratio ≥ 2 for all subgroups). Length of hospital stay for women was significantly longer in all depression subtypes (p < 0.001).

CONCLUSIONS

Elevated rates of inpatient treatment in women cannot solely be explained by a higher MDD prevalence and are dependent on age and type of depressive episode. Irrespective of the type and severity of the mood episode, women exhibit longer hospitalisation times.

Temporal Relationship Between Depressive Symptoms and Cognition in Mid and Late Life: A Longitudinal Cohort Study

OBJECTIVES

To examine the bidirectional temporal relationship between depressive symptoms and cognition in relation to risk, reaction, and prodrome.

DESIGN

Cross-lag analysis of longitudinal data collected online at baseline and 12-month follow-up.

SETTING AND PARTICIPANTS

A United Kingdom population cohort of 11,855 participants aged 50 years and over.

MEASURES

Patient Health Questionnaire-9 (depressive symptoms), cognitive measures: Paired Associate Learning, Verbal Reasoning, Spatial Working Memory, and Digit Span.

RESULTS

Depressive symptoms predicted a decline in paired associates learning [β = -.020, P = .013, (95% confidence interval [CI], ‒.036, -.004)] and verbal reasoning [β = -.014, P = .016, (95% CI ‒.025, -.003)] but not vice versa. Depressive symptoms predicted [β = -.043, P < .001, (95% CI ‒.060, -.026); β = -.029, P < .001, (95% CI ‒.043, -.015)] and were predicted by [β = -.030, P = < .001, (95% CI ‒.047, -.014); β = -.025, P = .003, (95% CI ‒.041, -.009)], a decline in spatial working memory and verbal digit span, respectively.

CONCLUSIONS AND IMPLICATIONS

Depressive symptoms may be either a risk factor or prodrome for cognitive decline. In addition, a decline in attention predicts depressive symptoms. Clinical implications and implications for further research are discussed.

Stress and the Etiopathogenesis of Alzheimer's Disease and Depression

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder with a complex physiopathology whose initiators are poorly defined. Accumulating clinical and experimental evidence suggests a causal role of lifetime stress in AD. This chapter summarizes current knowledge about how chronic stress and its accompanying high levels of glucocorticoid (GC) secretion, trigger the two main pathomechanisms of AD: (i) misprocessing of amyloid precursor protein (APP) and the generation of amyloid beta (Aβ) and (ii) Tau hyperphosphorylation and aggregation. Given that depression is a well-known stress-related illness, and the evidence that depression may precede AD, this chapter also explores neurobiological mechanisms that may be common to depressive and AD pathologies. This review also discusses emerging insights into the role of Tau and its malfunction in disrupting neuronal cascades and neuroplasticity and, thus triggering brain pathology.

Drugs related to monoamine oxidase activity

Progress in understanding the role of monoamine neurotransmission in pathophysiology of neuropsychiatric disorders was made after the discovery of the mechanisms of action of psychoactive drugs, including monoamine oxidase (MAO) inhibitors. The increase in monoamine neurotransmitter availability, decrease in hydrogen peroxide production, and neuroprotective effects evoked by MAO inhibitors represent an important approach in the development of new drugs for the treatment of mental disorders and neurodegenerative diseases. New drugs are synthesized by acting as multitarget-directed ligands, with MAO, acetylcholinesterase, and iron chelation as targets. Basic information is summarized in this paper about the drug-induced regulation of monoaminergic systems in the brain, with a focus on MAO inhibition. Desirable effects of MAO inhibition include increased availability of monoamine neurotransmitters, decreased oxidative stress, decreased formation of neurotoxins, induction of pro-survival genes and antiapoptotic factors, and improved mitochondrial functions.

Depression as a risk factor for Alzheimer's disease: Genes, steroids, cytokines and neurogenesis - What do we need to know?

Depression (MDD) is prodromal to, and a component of, Alzheimer's disease (AD): it may also be a trigger for incipient AD. MDD is not a unitary disorder, so there may be particular subtypes of early life MDD that pose independent high risks for later AD, though the identification of these subtypes is problematical. There may either be a common pathological event underlying both MDD and AD, or MDD may sensitize the brain to a second event ('hit') that precipitates AD. MDD may also accelerate brain ageing, including altered DNA methylation, increased cortisol but decreasing DHEA and thus the risk for AD. So far, genes predicting AD (e.g. APOEε4) are not risk factors for MDD, and those implicated in MDD (e.g. SLC6A4) are not risks for AD, so a common genetic predisposition looks unlikely. There is as yet no strong indication that an epigenetic event occurs during some forms of MDD that predisposes to later AD, though the evidence is limited. Glucocorticoids (GCs) are disturbed in some cases of MDD and in AD. GCs have marked degenerative actions on the hippocampus, a site of early β-amyloid deposition, and rare genetic variants of GC-regulating enzymes (e.g. 11β-HSD) predispose to AD. GCs also inhibit hippocampal neurogenesis and plasticity, and thus episodic memory, a core symptom of AD. Disordered GCs in MDD may inhibit neurogenesis, but the contribution of diminished neurogenesis to the onset or progression of AD is still debated. GCs and cytokines also reduce BDNF, implicated in both MDD and AD and hippocampal neurogenesis, reinforcing the notion that those cases of MDD with disordered GCs may be a risk for AD. Cytokines, including IL1β, IL6 and TNFα, are increased in the blood in some cases of MDD. They also reduce hippocampal neurogenesis, and increased cytokines are a known risk for later AD. Inflammatory changes occur in both MDD and AD (e.g. raised CRP, TNFα). Both cytokines and GCs can have pro-inflammatory actions in the brain. Inflammation (e.g. microglial activation) may be a common link, but this has not been systematically investigated. We lack substantial, rigorous and comprehensive follow-up studies to better identify possible subtypes of MDD that may represent a major predictor for later AD. This would enable specific interventions during critical episodes of these subtypes of MDD that should reduce this substantial risk.

Hippocampus atrophy and the longitudinal course of late-life depression

OBJECTIVES

Smaller hippocampal volumes are observed in depression but it remains unclear how antidepressant response and persistent depression relate to changes in hippocampal volume. We examined the longitudinal relationship between hippocampal atrophy and course of late-life depression.

SETTING

Academic medical center.

PARTICIPANTS

Depressed and never-depressed cognitively intact subjects age 60 years or older.

MEASUREMENTS

Depression severity was measured every three months with the Montgomery-Asberg Depression Rating Scale (MADRS). Participants also completed cranial 1.5-T magnetic resonance imaging every 2 years. We compared 2-year change in hippocampal volume based on remission status, then in expanded analyses examined how hippocampal volumes predicted MADRS score.

RESULTS

In analyses of 92 depressed and 70 never-depressed subjects, over 2 years the cohort whose depression never remitted exhibited greater hippocampal atrophy than the never-depressed cohort. In expanded analyses of a broader sample of 152 depressed elders, depression severity was significantly predicted by a hippocampus × time interaction where smaller hippocampus volumes over time were associated with greater depression severity.

CONCLUSIONS

Hippocampal atrophy is associated with greater and persistent depression severity. Neuropathological studies are needed to determine if this atrophy is related to the toxic effects of persistent depression or related to underlying Alzheimer disease.

Soluble amyloid-β levels and late-life depression

Late-Life Major Depression (LLMD) is a complex heterogeneous disorder that has multiple pathophysiological mechanisms such as medical comorbidity, vascular-related factors and Alzheimer's disease (AD). There is an association between LLMD and AD, with LLMD possibly being a risk factor for, or early symptom of AD and vascular dementia. Whether depression is an etiologic risk factor for dementia, or part of the dementia prodrome remains controversial. AD has a long prodromal period with the neuropathologic features of the disease preceding the onset of clinical symptoms by as much as 15-20 years. Clinicopathological studies have provided robust support for the importance of Aβ42 in the pathogenesis of AD, but several other risk factors have also been identified. Given the relationship between Aβ42 and AD, a potential relationship between Aβ42 and LLMD would improve the understanding of the association between LLMD and AD. We reviewed 15 studies that analyzed the relationship between soluble Aβ42 and LLMD. For studies looking at plasma and/or cerebrospinal fluid (CSF) levels of Aβ42, the relationship between LLMD and soluble Aβ42 was equivocal, with some studies finding elevated Aβ42 levels associated with LLMD and others finding the opposite, decreased levels of Aβ42 associated with LLMD. It may be that there is poor reliability in the diagnosis of depression in late life, or variability in the criteria and the scales used, or subtypes of depression in late life such as early vs. late onset depression, vascular-related depression, and preclinical/comorbid depression in AD. The different correlations associated with each of these factors would be causing the inconsistent results for soluble Aβ42 levels in LLMD, but it is also possible that these patterns derive from disease stage-dependent differences in the trajectory of CSF Aβ42 during older age, or changes in neuronal activity or the sleep/wake cycle produced by LLMD that influence Aβ42 dynamics.

Midlife vs late-life depressive symptoms and risk of dementia: differential effects for Alzheimer disease and vascular dementia

CONTEXT

Depression and dementia are common in older adults and often co-occur, but it is unclear whether depression is an etiologic risk factor for dementia.

OBJECTIVE

To clarify the timing and nature of the association between depression and dementia.

DESIGN

We examined depressive symptoms assessed in midlife (1964-1973) and late life (1994-2000) and the risks of dementia, Alzheimer disease (AD), and vascular dementia (VaD) (2003-2009) in a retrospective cohort study. Depressive symptoms were categorized as none, midlife only, late life only, or both. Cox proportional hazards models (age as timescale) adjusted for demographics and medical comorbidities were used to examine depressive symptom category and risk of dementia, AD, or VaD.

SETTING

Kaiser Permanente Medical Care Program of Northern California.

PARTICIPANTS

Thirteen thousand five hundred thirty-five long-term Kaiser Permanente members.

MAIN OUTCOME MEASURE

Any medical record diagnosis of dementia or neurology clinic diagnosis of AD or VaD.

RESULTS

Subjects had a mean (SD) age of 81.1 (4.5) years in 2003, 57.9% were women, and 24.2% were nonwhite. Depressive symptoms were present in 14.1% of subjects in midlife only, 9.2% in late life only, and 4.2% in both. During 6 years of follow-up, 22.5% were diagnosed with dementia (5.5% with AD and 2.3% with VaD). The adjusted hazard of dementia was increased by approximately 20% for midlife depressive symptoms only (hazard ratio, 1.19 [95% CI, 1.07-1.32]), 70% for late-life symptoms only (1.72 [1.54-1.92]), and 80% for both (1.77 [1.52-2.06]). When we examined AD and VaD separately, subjects with late-life depressive symptoms only had a 2-fold increase in AD risk (hazard ratio, 2.06 [95% CI, 1.67-2.55]), whereas subjects with midlife and late-life symptoms had more than a 3-fold increase in VaD risk (3.51 [2.44-5.05]).

CONCLUSIONS

Depressive symptoms in midlife or in late life are associated with an increased risk of developing dementia. Depression that begins in late life may be part of the AD prodrome, while recurrent depression may be etiologically associated with increased risk of VaD.

Depression, hypothalamic pituitary adrenal axis, and hippocampal and entorhinal cortex volumes--the SMART Medea study

BACKGROUND

Structural brain changes have often been found in major depressive disorder (MDD), and it is thought that hypothalamic-pituitary-adrenal (HPA) axis hyperactivity may explain this relation. We investigated the association of MDD and history of depression with hippocampal and entorhinal cortex volumes and whether HPA axis activity explained this association.

METHODS

In 636 participants with a history of atherosclerotic disease (mean age 62 ± 9 years, 81% male) from the second Manifestation of ARTerial disease-Memory depression and aging (SMART-Medea) study, a 12-month diagnosis of MDD and history of depression were assessed. Age of first depressive episode was classified into early-onset depression (< 50 years) and late-onset depression (≥ 50 years). HPA axis regulation was assessed by four morning saliva samples, two evening samples, and one awakening sample after .5 mg dexamethasone. Hippocampus and entorhinal cortex volume were manually outlined on three-dimensional T1-weighted magnetic resonance images.

RESULTS

General linear models adjusted for demographics, vascular risk, antidepressant use, and white matter lesions showed that ever having had MDD was associated with smaller hippocampal volumes but not with entorhinal cortex volumes. Remitted MDD was related to smaller entorhinal cortex volumes (p < .05). Participants with early-onset depression had smaller hippocampal volumes than those who were never depressed (p < .05), whereas participants with late-onset depression had smaller entorhinal cortex volumes (p < .05). HPA axis activity did not explain these differences.

CONCLUSIONS

We found differential associations of age of onset of depression on hippocampal and entorhinal cortex volumes, which could not be explained by alterations in HPA axis regulation.

The structure and validity of self-reported affect in mild cognitive impairment and mild Alzheimer's disease

BACKGROUND

This study determined the reliability, validity, and factor structure of self-report emotions in persons with mild Alzheimer's disease (AD) and mild cognitive impairment (MCI) relative to controls.

METHODS

Participants (mild AD, n = 73; MCI, n = 159; controls, n = 96) rated current emotions with the Visual Analogue Mood Scales (Stern, 1997).

RESULTS

Internal consistency reliabilities were comparable across groups, as were the factor structures of emotion. Persons with AD reported more negative affect (NA) than persons with MCI and controls. The emotion that most differentiated groups was confusion. NA and PA may be more bipolar in persons with AD than for persons with MCI and controls.

CONCLUSIONS

The underlying structure of affect was similar in persons with mild AD, MCI, and controls. Further, persons with MCI appeared to be "transitional" between cognitive health and dementia with regard to mood and affect. That is, participants with MCI tended to have affect scores that were intermediate between those with AD and controls. Implications for interventions to improve emotional well-being in AD and MCI are discussed.

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.

Case for and against specificity of depression in Alzheimer's disease

AIMS

The aims of this study were to assess the epidemiological, phenomenological, and pathophysiological evidence that suggests the specificity of depression associated with Alzheimer's disease (AD).

METHODS

We reviewed the English-language literature.

RESULTS

Depression occurs significantly more often in patients with AD than in the general elderly population. While development of depression in response to the disability and emotional stress of AD may be a contributory factor in some patients, several studies showed that depression was not, or was only seldom, related to self-awareness of AD and these studies could not explain the high prevalence figures. To overcome the overlapping phenomenology of the two diseases, specific diagnostic criteria have been developed for depression in this context. Mixed findings have come from neuropathological and neuroimaging studies, with some evidence linking the underlying neural substrate of AD and depression, suggesting an overlapping cause of primary depression and depression comorbid with AD. Few randomized controlled trials for depression associated with AD have been conducted, with rather poor results for the use of antidepressants.

CONCLUSIONS

Currently, depression associated with AD is not considered a separate disorder by regulatory authorities and is unlikely to be considered as such in the near future. Several obstacles remain to support such a specific position, including the heterogenous nature of depression in general and within AD itself, the lack of a distinct set of symptoms, and limited treatment.

Depression vs. Dementia: A comparative analysis of neuropsychological functions

Previous studies concerned with neuropsychological aspect of depression, detected comparatively specific profile of cognitive deficiencies, including the disorders of attention, memory and executive functions. Although the classical depression is recognized as psuedodementia, or reversible dementia, these two entities frequently overlap in the elder population. Many patients who are at first depressive, become demented later, and the initial stages of dementia are not rarely accompanied with mood changes. The aim of this study is the establishing of differences between neuropsychological profiles of depression and dementia. The sample included three groups: the first group represented the patients with endogenous depression, the second - the patients with dementia, and the third one - healthy individuals. The participants have been tested by a neuropsychological battery. Two patient groups were tested during the stage of remission/adequate mood. Abilities most susceptible to depression are: attention, executive functions and memory. Cognitive flexibility and general cognitive ability are preserved in depressive patients. Depressive patients express cognitive disorders of moderate degree during the remission stage. Impairment pattern in the group of depressive patients does not indicate intellectual degradation of the dementia type. Neuropsychological deficiencies of the patients with endogenous depression suggest frontal limbic dysfunction. Excesses in cognitive functioning of demented patients are more serious and massive in comparison with cognitive difficulties in depressive patients.

Smell test predicts performance on delayed recall memory test in elderly with depression

INTRODUCTION

Elderly with depression are at increased risk for cognitive dysfunction and dementia. Smell tests are correlated with performance on cognitive tests in the elderly and therefore might serve as a screening test for cognitive impairment in depressed elderly.

PURPOSE

To assess the validity of the CC-SIT (Cross-Cultural Smell Identification Test) as a screening test for cognitive impairment in elderly with depression.

METHODS

Forty-one patients, aged 60 and over, were assessed with the CC-SIT and CVLT (California Verbal Learning Test) after 3 months treatment of a Major Depressive Episode (DSM-IV) at the Day Hospital for Depression, Baycrest. Patients already diagnosed with dementia, or other psychiatric and neurological disorders, were excluded. Receiver Operating Characteristics (ROC) analysis was applied to assess the CC-SIT's accuracy in identifying individuals with impairment (2 SD below the mean for age and education or less) on CVLT delayed recall trials.

RESULTS

Forty-one patients (33 women and eight men) were assessed. Mean age was 76.8 (SD: 6.5), mean HRSD scores before treatment was 22.0 (SD: 5.1). Nine patients had impairment on CVLT delayed recall measures. The area under the ROC curve was 0.776 (95% CI = 0.617-0.936).

CONCLUSIONS

Our results support the use of the CC-SIT as a screening tool for cognitive impairment among elderly with depression as an indicator for the need of a comprehensive neuropsychological evaluation. Replication with larger samples is necessary.

Stress and glucocorticoid footprints in the brain-the path from depression to Alzheimer's disease

Increasingly, stress is recognized as a trigger of depressive episodes and recent evidence suggests a causal role of stress in the onset and progression of Alzheimer's disease (AD) pathology. Besides aging, sex is an important determinant of prevalence rates for both AD and mood disorders. In light of a recent meta-analysis indicating that depressed subjects have a higher likelihood of developing AD, a key message in this article will be that both depression and AD are stress-related disorders and may represent a continuum that should receive more attention in future neurobiological studies. Accordingly, this review considers some of the cellular mechanisms that may be involved in regulating this transition threshold. In addition, it highlights the importance of addressing the question of how aging and sex interplay with stress to influence mood and cognition, with a bias towards consideration of neuroplastic events in particular brain regions, as the basis of AD and depressive disorders.

Distinguishing between depression and dementia in older persons: neuropsychological and neuropathological correlates

Dementia and depression are frequently comorbid among older adult patients. Depression is related to cognitive decrement and can even represent the first signs of a neurodegenerative process. It can be difficult to distinguish depressed patients exhibiting the first signs of dementia from those whose cognition will improve with treatment. In this article, studies from the neuropsychological literature are reviewed that aid in accurate diagnosis and prognosis. Furthermore, the relationship between depression and dementia is explored by examining potential neurobiological mechanisms that may potentiate both syndromes in the context of the ongoing debate on depression as a prodrome and/or a risk factor for dementia. This article is concluded with suggestions for clinicians when deciding who to refer for neuropsychological assessment and with ideas for further research that might promote a better understanding of the complex association between depression and dementia during old age.

Is lower cognitive function in one spouse associated with depressive symptoms in the other spouse?

This study examines whether lower cognitive function in one spouse is associated with depressive symptoms in the other spouse. The subjects were 528 community-dwelling spouse pairs aged 65+ who participated in the Chicago Health and Aging Project (CHAP), an ongoing longitudinal, bi-racial, population-based study of risk factors for incident Alzheimer's disease and other age-related chronic conditions. CHAP participants were assessed at 3-year intervals over a period of nearly ten years. The results show a cross-sectional association of wives' lower cognitive function at baseline with depressive symptoms in husbands; however, husbands' cognitive function was not associated with wives' depressive symptoms. There was no longitudinal association of cognitive function at baseline with increased depressive symptoms over time. Furthermore, change in cognitive function over time had no effect on depressive symptoms in either spouse. The relationship between cognitive function and depressive symptoms in spouse pairs is complex. Our findings suggest that husbands may be particularly psychologically vulnerable to the negative effects of their wives' cognitive impairment. This vulnerability may have a range of long-term health and caregiving implications.