Cognitive impairment in depression is not associated with neuropathologic evidence of increased vascular or Alzheimer-type pathology

[Which Treatment Setting is Suited for Forensic Inpatients Aged≥60 Years?A Systemic Literature Analysis]

In the inpatient correctional system, the question of a suitable treatment setting for older forensic inpatients (i. e. ≥60 years) arises against the background of demographic change. In this regard, the research literature was examined using four medical databases (PsycInfo, Medline, Embase, Web of Science) for relevant keywords (elderly offender/perpetrator, aged, mental disorder, forensic treatment, forensic psychiatry). Out of 744 pre-selected articles, only 5 studies made it into the final selection. The majority of the sample is composed of men with previous criminal justice experience, who may be mentally and/or physically ill. Placement and capacity problems as well as a lack of age-appropriate infrastructure are reported. Based on the study results, an empirical recommendation regarding a suitable treatment setting cannot be given.

The heterogeneity of late-life depression and its pathobiology: a brain network dysfunction disorder

Depression is frequent in older individuals and is often associated with cognitive impairment and increasing risk of subsequent dementia. Late-life depression (LLD) has a negative impact on quality of life, yet the underlying pathobiology is still poorly understood. It is characterized by considerable heterogeneity in clinical manifestation, genetics, brain morphology, and function. Although its diagnosis is based on standard criteria, due to overlap with other age-related pathologies, the relationship between depression and dementia and the relevant structural and functional cerebral lesions are still controversial. LLD has been related to a variety of pathogenic mechanisms associated with the underlying age-related neurodegenerative and cerebrovascular processes. In addition to biochemical abnormalities, involving serotonergic and GABAergic systems, widespread disturbances of cortico-limbic, cortico-subcortical, and other essential brain networks, with disruption in the topological organization of mood- and cognition-related or other global connections are involved. Most recent lesion mapping has identified an altered network architecture with "depressive circuits" and "resilience tracts", thus confirming that depression is a brain network dysfunction disorder. Further pathogenic mechanisms including neuroinflammation, neuroimmune dysregulation, oxidative stress, neurotrophic and other pathogenic factors, such as β-amyloid (and tau) deposition are in discussion. Antidepressant therapies induce various changes in brain structure and function. Better insights into the complex pathobiology of LLD and new biomarkers will allow earlier and better diagnosis of this frequent and disabling psychopathological disorder, and further elucidation of its complex pathobiological basis is warranted in order to provide better prevention and treatment of depression in older individuals.

Differential Diagnosis Between Alzheimer's Disease-Related Depression and Pseudo-Dementia in Depression: A New Indication for Amyloid-β Imaging?

BACKGROUND

Alzheimer's disease and depression can start with combined cognitive and depressive symptoms [1, 2]. Accurate differential diagnosis is desired to initiate specific treatment.

OBJECTIVE

We investigated whether amyloid-β PET imaging can discriminate both entities.

METHODS

This retrospective observational study included 39 patients (20 female, age = 70±11years) with both cognitive and depressive symptoms who underwent amyloid-β PET imaging and in whom clinical follow-up data was available. Amyloid-β PET was carried out applying [18F]Florbetaben or [11C]PiB. The PET images were analyzed by standardized visual and relative-quantitative evaluation. Based on clinical follow-up (median of 2.4 years [range 0.3 to 7.0 years, IQR = 3.7 years] after amyloid PET imaging which was not considered in obtaining a definite diagnosis), discrimination ability between AD-related depression and pseudo-dementia in depression/depression with other comorbidities was determined.

RESULTS

Visually, all 10 patients with pseudo-dementia in depression and all 15 patients with other depression were rated as amyloid-β-negative; 2 of 14 patients with AD-related depression were rated amyloid-β-negative. ROC curve analysis of the unified composite standardized uptake value ratios (cSUVRs) was able to discriminate pseudo-dementia in depression from AD-related depression with high accuracy (AUC = 0.92). Optimal [18F]Florbetaben discrimination cSUVR threshold was 1.34. In congruence with the visual PET analysis, the resulting sensitivity of the relative-quantitative analysis was 86% with a specificity of 100% .

CONCLUSION

Amyloid-β PET can differentiate AD-related depression and pseudo-dementia in depression. Prospective clinical studies are warranted to confirm this result and to potentially broaden the spectrum of clinical applications for amyloid-β PET imaging.

Microvascular Contribution to Late-Onset Depression: Mechanisms, Current Evidence, Association With Other Brain Diseases, and Therapeutic Perspectives

Depression is common in older individuals and is associated with high disability and mortality. A major problem is treatment resistance: >50% of older patients do not respond to current antidepressants. Therefore, new effective interventions for prevention and treatment of depression in older individuals need to be developed, which requires a better understanding of the mechanisms underlying depression. The pathophysiology of depression is multifactorial and complex. Microvascular dysfunction may be an early and targetable mechanism in the development of depression, notably depression that initiates in late life (late-onset depression). Late-onset depression commonly co-occurs with other diseases or syndromes that may share a microvascular origin, including apathy, cognitive impairment, dementia, and stroke. Together, these disabilities may all be part of one large phenotype resulting from global cerebral microvascular dysfunction. In this review, we discuss the pathophysiology of microvascular dysfunction-related late-onset depression, summarize recent epidemiological evidence on the association between cerebral microvascular dysfunction and depression, and indicate potential drivers of cerebral microvascular dysfunction. We also propose the hypothesis that depression may be a manifestation of a larger phenotype of cerebral microvascular dysfunction, highlight potential therapeutic targets and interventions, and give directions for future research.

Mechanisms and Treatment of Late-Life Depression

(Appeared originally in Translational Psychiatry 2019; 9:188).

Trauma and depressive symptomatology in middle-aged persons at high risk of dementia: the PREVENT Dementia Study

OBJECTIVE

Depression and trauma are associated with changes in brain regions implicated in Alzheimer's disease. The present study examined associations between childhood trauma, depression, adult cognitive functioning and risk of dementia.

METHODS

Data from 378 participants in the PREVENT Dementia Study aged 40-59 years. Linear and logistic models were used to assess associations between childhood trauma, depression, dementia risk, cognitive test scores and hippocampal volume.

RESULTS

Childhood trauma was associated with depression and reduced hippocampal volume but not current cognitive function or dementia risk. Poorer performance on a delayed face/name recall task was associated with depression. Childhood trauma was associated with lower hippocampal volume however poorer cognitive performance was mediated by depression rather than structural brain differences.

CONCLUSION

Depressive symptomatology may be associated with dementia risk via multiple pathways, and future studies should consider subtypes of depressive symptomatology when examining its relationship to dementia.

Mechanisms and treatment of late-life depression

Depression predisposes to medical illnesses and advances biological aging indicated by shorter telomere length, accelerated brain aging and advanced epigenetic aging. Medical illnesses also increase the risk of late-life depression. The reciprocal relationships of depression with aging-related and disease-related processes have generated pathogenetic hypotheses and provided treatment targets. Targeting risk factors of vascular disease in mid-life is a logical approach in prevention of vascular depression. The depression-executive dysfunction and the vascular depression syndromes have clinical presentations and neuroimaging findings consistent with frontostriatal abnormalities. Dopamine D_2/3 agonists are effective in depression of Parkinson's disease and their efficacy needs to be assessed in these two syndromes. Computerized cognitive remediation targeting functions of the cognitive control network may improve both executive functions and depressive symptoms of late-life major depression. Significant progress has been made in neurostimulation treatments in depressed younger adults. TMS targeting deep structures responsible for mood regulation is well tolerated by older adults and its efficacy in syndromes of late-life depression needs to be studied. Efficacious psychotherapies for late-life depression exist, but are underutilized in part because of their complexity. Streamlined, stepped psychotherapies targeting behaviors assumed to result from dysfunction of brain networks implicated in late-life depression can be easy to learn and have potential for dissemination. However, their effectiveness needs further investigation. Depression increases the risk of dementing disorders. Antidepressants are rather ineffective in treating depression of demented patients, but long-term use of antidepressants may reduce the risk of dementia. However, confirmation studies are needed.

Tau in Late-Life Depression: A Systematic Review and Meta-Analysis

A lifetime history of major depressive disorder (MDD) increases the risk of developing Alzheimer's disease, of which neurofibrillary tangles due to abnormal tau proteins are a hallmark. We systematically reviewed the literature on tau in MDD and identified 49 relevant articles spanning a number of modalities, including cerebrospinal fluid (CSF) analysis, positron emission tomography, and clinicopathological correlation. We compared CSF total and phosphorylated tau proteins in MDD and controls using a meta-analytic approach. We found no difference in total or phosphorylated tau in MDD. We also found no difference in a comparison of a subgroup excluding studies with significant age differences. Positron emission tomography studies lacked specificity. Clinicopathological studies failed to associate neurofibrillary tangles with MDD. The available data on tau in MDD is limited. The involvement of tau in a subset of MDD cannot be ruled out and requires prospective exploration.

Clinicopathological correlates of depression in early Alzheimer's disease in the NACC

OBJECTIVE

Depression may be a prodrome to Alzheimer's disease (AD). We assessed whether AD neuropathology is associated with depression in mild cognitive impairment (MCI) and mild dementia (dAD).

METHODS

All clinical and neuropathological data for this study came from the National Alzheimer's Coordinating Center (NACC). Healthy control (HC, n = 120), MCI (n = 77), and mild dAD (n = 93) patients who underwent brain autopsy were included. In regression models with Geriatric Depression Scale (GDS) as the outcome, neuritic plaque (NP) score or Braak Stages of neurofibrillary (NF) pathology were covariates.

RESULTS

GDS was not associated with cognitive status, NP score, Braak Stages, or their interaction. In both models, a history of TIAs, depression within the last 2 years, current benzodiazepine use, and greater severity of neuropsychiatric symptoms were associated with greater depression. In the Braak Stages model, less education was another significant predictor.

CONCLUSIONS

Depression in early AD appears to be independent of NP and NF pathology. Studies are needed to investigate other mechanisms that may be responsible for depression in MCI and dAD.

Chronic stress and hippocampal dendritic complexity: Methodological and functional considerations

The current understanding of how chronic stress impacts hippocampal dendritic arbor complexity and the subsequent relationship to hippocampal-dependent spatial memory is reviewed. A surge in reports investigating hippocampal dendritic morphology is occurring, but with wide variations in methodological detail being reported. Consequently, this review systematically outlines the basic neuroanatomy of relevant hippocampal features to help clarify how chronic stress or glucocorticoids impact hippocampal dendritic complexity and how these changes occur in parallel with spatial cognition. Chronic stress often leads to hippocampal CA3 apical dendritic retraction first with other hippocampal regions (CA3 basal dendrites, CA1, dentate gyrus, DG) showing dendritic retraction when chronic stress is sufficiently robust or long lasting. The stress-induced reduction in hippocampal CA3 apical dendritic arbor complexity often coincides with impaired hippocampal function, such as spatial learning and memory. Yet, when chronic stress ends and a post-stress recovery period ensues, the atrophied dendritic arbors and poor spatial abilities often improve. However, this process differs from a simple reversal of chronic stress-induced deficits. Recent reports suggest that this return to baseline-like functioning is uniquely different from non-stressed controls, emphasizing the need for further studies to enhance our understanding of how a history of stress subsequently alters an organism's spatial abilities. To provide a consistent framework for future studies, this review concludes with an outline for a quick and easy reference on points to consider when planning chronic stress studies with the goal of measuring hippocampal dendritic complexity and spatial ability.

Vascular depression consensus report - a critical update

BACKGROUND

Vascular depression is regarded as a subtype of late-life depression characterized by a distinct clinical presentation and an association with cerebrovascular damage. Although the term is commonly used in research settings, widely accepted diagnostic criteria are lacking and vascular depression is absent from formal psychiatric manuals such as the Diagnostic and Statistical Manual of Mental Disorders, 5^th edition - a fact that limits its use in clinical settings. Magnetic resonance imaging (MRI) techniques, showing a variety of cerebrovascular lesions, including extensive white matter hyperintensities, subcortical microvascular lesions, lacunes, and microinfarcts, in patients with late life depression, led to the introduction of the term "MRI-defined vascular depression".

DISCUSSION

This diagnosis, based on clinical and MRI findings, suggests that vascular lesions lead to depression by disruption of frontal-subcortical-limbic networks involved in mood regulation. However, despite multiple MRI approaches to shed light on the spatiotemporal structural changes associated with late life depression, the causal relationship between brain changes, related lesions, and late life depression remains controversial. While postmortem studies of elderly persons who died from suicide revealed lacunes, small vessel, and Alzheimer-related pathologies, recent autopsy data challenged the role of these lesions in the pathogenesis of vascular depression. Current data propose that the vascular depression connotation should be reserved for depressed older patients with vascular pathology and evident cerebral involvement. Based on current knowledge, the correlations between intra vitam neuroimaging findings and their postmortem validity as well as the role of peripheral markers of vascular disease in late life depression are discussed.

CONCLUSION

The multifold pathogenesis of vascular depression as a possible subtype of late life depression needs further elucidation. There is a need for correlative clinical, intra vitam structural and functional MRI as well as postmortem MRI and neuropathological studies in order to confirm the relationship between clinical symptomatology and changes in specific brain regions related to depression. To elucidate the causal relationship between regional vascular brain changes and vascular depression, animal models could be helpful. Current treatment options include a combination of vasoactive drugs and antidepressants, but the outcomes are still unsatisfying.

Organic bases of late-life depression: a critical update

Late-life depression (LLD) is frequently associated with cognitive impairment and increases the risk of subsequent dementia. Cerebrovascular disease, deep white matter lesions, Alzheimer disease (AD) and dementia with Lewy bodies (DLB) have all been hypothesized to contribute to this increased risk, and a host of studies have looked at the interplay between cerebrovascular disease and LLD. This has resulted in new concepts of LLD, such as "vascular depression", but despite multiple magnetic resonance imaging (MRI) studies in this field, the relationship between structural changes in human brain and LLD is still controversial. While pathological findings of suicide in some elderly persons revealed multiple lacunes, small vessel cerebrovascular disease, AD-related lesions or multiple neurodegenerative pathologies, recent autopsy data challenged the role of subcortical lacunes and white matter lesions as major morphological substrates of depressive symptoms as well as poorer executive function and memory. Several neuropathological studies, including a personal clinico-pathological study in a small cohort of elderly persons with LLD and age-matched controls confirmed that lacunes, periventricular and deep white matter demyelination as well as AD-related lesions are usually unrelated to the occurrence of LLD. In the same line, neuropathological data show that early-onset depression is not associated with an acceleration of age-related neurodegenerative changes. Very recent data on the critical role of glia-modulating neuronal dysfunction and degeneration in depression are discussed.

The effects of chronic glucocorticoid exposure on dendritic length, synapse numbers and glial volume in animal models: implications for hippocampal volume reductions in depression

Glucocorticoids (GCs) are hormones secreted by the adrenal glands as an endocrine response to stress. Although the main purpose of GCs is to restore homeostasis when acutely elevated, animal studies indicate that chronic exposure to these hormones can cause damage to the hippocampus. This is indicated by reductions in hippocampal volume, and changes in neuronal morphology (i.e., decreases in dendritic length and number of dendritic branch points) and ultrastructure (e.g., smaller synapse number). Smaller hippocampal volume has been also reported in humans diagnosed with major depressive disorder or Cushing's disorder, conditions in which GCs are endogenously and chronically elevated. Although a number of studies considered neuron loss as the major factor contributing to the volume reduction, recent findings indicated that this is not the case. Instead, alterations in dendritic, synaptic and glial processes have been reported. The focus of this paper is to review the GC effects on the cell number, dendritic morphology and synapses in an effort to better understand how these changes may contribute to reductions in hippocampal volume. Taken together, the data from animal models suggest that hippocampal volumetric reductions represent volume loss in the neuropil, which, in turn, under-represent much larger losses of dendrites and synapses.

Depression and anxiety symptoms are associated with cerebral FDDNP-PET binding in middle-aged and older nondemented adults

OBJECTIVES

Amyloid senile plaques and tau neurofibrillary tangles are neuropathologic hallmarks of Alzheimer disease, which may be associated with mild cognitive impairment (MCI) or mood and anxiety symptoms years before the dementia diagnosis. To address this issue, the authors obtained positron emission tomography (PET) scans after intravenous injections of 2-(1-{6-[(2-[fluorine-18]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile (FDDNP), a molecule that binds to amyloid plaques and neurofibrillary tangles, to determine whether symptoms of depression and anxiety in nondemented subjects were associated with increased FDDNP-PET binding values.

METHODS

Forty-three middle-aged and elderly volunteers received clinical and FDDNP-PET assessments. Subjects were nondemented--23 of them were diagnosed with MCI and 20 were cognitively normal. Subjects with a diagnosis of major depression or an anxiety disorder were excluded. Correlations between standardized measures of depressive and anxiety symptoms and regional FDDNP binding values were calculated.

RESULTS

The MCI and comparison subjects did not differ by the depression and anxiety scores. In the MCI group, depression scores correlated with lateral temporal and trait anxiety scores correlated with posterior cingulate FDDNP binding. In the comparison group, depression scores correlated with medial temporal, and trait anxiety scores correlated with medial temporal and frontal FDDNP binding.

DISCUSSION

This is the first report to demonstrate a relationship between the severity of depression and anxiety symptoms and FDDNP binding values in nondemented middle age and older individuals. The results suggest a relationship between relatively mild mood symptoms and biomarkers of cerebral amyloid and tau deposition and vary according to degree of cognitive impairment. The presence of MCI may signify different pathophysiological mechanisms underlying mood and anxiety symptoms.

APOE-epsilon4, depressive symptoms, and cognitive decline in Chinese older adults: Singapore Longitudinal Aging Studies

BACKGROUND

The precise relationship between depression and cognitive decline in older adults is unclear. We investigated the influence of apolipoprotein E (APOE)-epsilon4 genotype in modulating the effect of depressive symptoms on cognitive decline.

METHODS

Prospective cohort study of 1,487 cognitively high-functioning Chinese older adults. Depressive symptoms (Geriatric Depression Scale score >/=5) and Mini-Mental State Examination (MMSE) were assessed at baseline, and cognitive decline (at least 1-point drop in MMSE) at 1-2 years after baseline.

RESULTS

There was no significant difference in cognitive decline between depressed (32.9%) and nondepressed (31.5%) participants in the whole sample or among non-APOE-epsilon4 carriers. Among APOE-epsilon4 carriers, depressed participants showed more cognitive decline (40.0%) than their nondepressed counterparts (28.6%), odds ratio = 2.89, 95% confidence interval: 1.03-8.12; p = .04, after controlling for age, gender, education, vascular risk factors/events, smoking, alcohol drinking, physical functioning, subjective memory complaint, length of follow-up, and baseline MMSE scores (p for interaction = .03).

CONCLUSIONS

Our study suggests that the presence of the APOE-epsilon4 allele significantly enhanced the risk of cognitive decline associated with depressive symptoms. This finding should be independently replicated in future studies.

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.

What causes the hippocampal volume decrease in depression? Are neurogenesis, glial changes and apoptosis implicated?

Even though in vivo imaging studies document significant reductions of hippocampal volume in depressed patients, the exact underlying cellular mechanisms are unclear. Since stressful life events are associated with an increased risk of developing depression, preclinical studies in which animals are exposed to chronic stress have been used to understand the hippocampal shrinkage in depressed patients. Based on morphometrical studies in these models, parameters like dendritic retraction, suppressed adult neurogenesis and neuronal death, all due to elevated levels of glucocorticoids, have been suggested as major causative factors in hippocampal shrinkage. However, histopathological studies examining hippocampi of depressed individuals have so far failed to confirm either a massive neuronal loss or a suppression of dentate neurogenesis, an event that is notably very rare in adult or elderly humans. In fact, many of the structural changes and the volume reduction appear to be reversible. Clearly, more histopathological studies are needed; especially ones that (a) employ stereological quantification, (b) focus on specific cellular elements and populations, and (c) are performed in nonmedicated depressed patients. We conclude that mainly other factors, like alterations in the somatodendritic, axonal, and synaptic components and putative glial changes are most likely to explain the hippocampal shrinkage in depression, while shifts in fluid balance or changes in the extracellular space cannot be excluded either.

[Validity of vascular depression as a specific diagnostic: a review]

INTRODUCTION

A number of authors have suggested that cerebrovascular disease may predispose, precipitate, or perpetuate some geriatric depressive syndromes. These "vascular depressions" may result from damage of striato-pallido-thalamo-cortical pathways which frequently occurs in cerebrovascular disease.

METHOD

We have searched the English and French literature published between 1996 (when the "vascular depression" hypothesis was first stated) and December 2004 through the Medline computer database and examined the validity of the concept of "vascular depression" thanks to four levels of validity: face validity, descriptive validity, construct validity and predictive validity. The face validity is the extent to which experts agree about the existence of a nosological entity.

RESULTS

The reviews published in this field broadly support the concept of "vascular depression" as a specific disorder. However many authors highlighted the fact that depression has been shown to precede vascular diseases and that depression and vascular diseases may both share some pathogenic or genetic determinants. These interactive and co-morbid relationships between depression and cerebrovascular diseases are difficult to disentangle. The descriptive validity refers to the degree of the clinical specificity of a disorder. It appears only moderate regarding the clinical studies carried out on this issue. However, a late-onset, the absence of a family history of mental illness, the lack of insight, lassitude, psychomotor retardation, a greater disability and particular neuropsychological dysfunctions may be associated with vascular depression. The construct validity, which refers to the degree to which the physiopathological processes involved in an illness are understood, appears difficult to establish because of the complex interactive relationships between cerebrovascular disease and depression. However, cerebrovascular diseases may contribute to the occurrence of depressive symptoms independently of its psychosocial burden. The predictive validity refers to the degree to which a syndrome is characterized by a specific response to treatment or a specific natural history. As regards response to treatment, vascular depression appears rather specific in the sense of a worse response to antidepressants and electroconvulsive therapy. The studies on the natural history of vascular depression lead to inconsistent results. According to some authors, this relative resistance to treatment may be explained by structural rather than functional, and thus potentially irreversible disruption in neural networks.

CONCLUSION

In conclusion, the systematic review of the validity of vascular depression broadly supports this concept. However, further studies are needed to decipher the relationships between depression and cerebrovascular disease. Finally, we suggest that it could be more relevant for future researches in this field if the diagnostic criteria for vascular depression were narrowed and required the presence of both neuro-imaging changes and cerebrovascular disease.

The stress system in depression and neurodegeneration: focus on the human hypothalamus

The stress response is mediated by the hypothalamo-pituitary-adrenal (HPA) system. Activity of the corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) forms the basis of the activity of the HPA-axis. The CRH neurons induce adrenocorticotropin (ACTH) release from the pituitary, which subsequently causes cortisol release from the adrenal cortex. The CRH neurons co-express vasopressin (AVP) which potentiates the CRH effects. CRH neurons project not only to the median eminence but also into brain areas where they, e.g., regulate the adrenal innervation of the autonomic system and affect mood. The hypothalamo-neurohypophysial system is also involved in stress response. It releases AVP from the PVN and the supraoptic nucleus (SON) and oxytocin (OXT) from the PVN via the neurohypophysis into the bloodstream. The suprachiasmatic nucleus (SCN), the hypothalamic clock, is responsible for the rhythmic changes of the stress system. Both centrally released CRH and increased levels of cortisol contribute to the signs and symptoms of depression. Symptoms of depression can be induced in experimental animals by intracerebroventricular injection of CRH. Depression is also a frequent side effect of glucocorticoid treatment and of the symptoms of Cushing's syndrome. The AVP neurons in the hypothalamic PVN and SON are also activated in depression, which contributes to the increased release of ACTH from the pituitary. Increased levels of circulating AVP are also associated with the risk for suicide. The prevalence, incidence and morbidity risk for depression are higher in females than in males and fluctuations in sex hormone levels are considered to be involved in the etiology. About 40% of the activated CRH neurons in mood disorders co-express nuclear estrogen receptor (ER)-alpha in the PVN, while estrogen-responsive elements have been found in the CRH gene promoter region, and estrogens stimulate CRH production. An androgen-responsive element in the CRH gene promoter region initiates a suppressing effect on CRH expression. The decreased activity of the SCN is the basis for the disturbances of circadian and circannual fluctuations in mood, sleep and hormonal rhythms found in depression. Neuronal loss was also reported in the hippocampus of stressed or corticosteroid-treated rodents and primates. Because of the inhibitory control of the hippocampus on the HPA-axis, damage to this structure was expected to disinhibit the HPA-axis, and to cause a positive feedforward cascade of increasing glucocorticoid levels over time. This 'glucocorticoid cascade hypothesis' of stress and hippocampal damage was proposed to be causally involved in age-related accumulation of hippocampal damage in disorders like Alzheimer's disease and depression. However, in postmortem studies we could not find the presumed hippocampal damage of steroid overexposure in either depressed patients or in patients treated with synthetic steroids.

White matter hyperintensities rather than lacunar infarcts are associated with depressive symptoms in older people: the LADIS study

OBJECTIVE

Both white matter hyperintensities (WMH) and lacunar infarcts have been associated with the development of depression in older subjects, although the relative importance of the two and the influence of lesion location and concomitant vascular disease are unclear. This study investigates the relationship between location and burden of WMH and lacunes on depressive features in older people.

METHOD

In a pan-European multicenter study of 626 older subjects, the authors examined the relationship between regional magnetic resonance imaging white matter hyperintensities, number of lacunar infarcts, depressive symptoms as assessed by the 15-item geriatric depression scale (GDS), cognitive status (Mini-Mental Status Examination), hypertension, and self-perceived health quality of life (QoL).

RESULTS

The authors found depressive symptoms to be correlated with WMH rating in the frontal (N=626; Spearman's rho=0.161, p <0.001) and temporal (rho=0.14, p <0.001) but not occipitoparietal region (rho=0.07, p=0.07). Basal ganglia lacunes were only weakly correlated with GDS (rho=0.09, p=0.03), and lacunes in other regions showed no association. In a ordinal logistic regression model (controlling for QoL, Mini-Mental Status Examination, age, and with an interaction between WMH and hypertension), temporal WMH in the absence of hypertension independently predicted GDS, whereas neither history of stroke nor number of lacunar infarcts did. The authors compared left- versus right-sided WMH and found no effect of laterality on depressive symptoms.

CONCLUSIONS

The results suggest that in this population of nondisabled older people, WMH have a greater influence on depressive symptoms than infarcts.

Relationship between periventricular and deep white matter lesions and depressive symptoms in older people. The LADIS Study

BACKGROUND

Both types of cerebral white matter hyperintensities, periventricular (PVL) and deep white matter lesions (DWML) have been previously associated with the development of depression in older subjects. However, it remains controversial as to whether PVL, DWML, or both are most strongly associated with depression and this was the aim of the current study.

METHODS

In a pan-European multicentre study of 626 older subjects, we examined the relationship between PVL and DWML, depressive symptoms (GDS quintile), cognitive status (MMSE), hypertension and history of stroke.

RESULTS

In univariate analysis we found that depressive symptoms as assessed by GDS were associated with both types of white matter lesions (Spearman rho = 0.12 p = 0.002 for DWML and rho = 0.09 p = 0.01 for PVL). Using ordinal logistic regression analysis the total DWML score (p = 0.041), rather than PVL (p = 0.9) was found to predict GDS scores.

CONCLUSIONS

DWML, but not PVL, were most strongly associated with depressive symptoms in this sample. As DWML (unlike PVL) are associated with vascular ischaemic damage, our findings are consistent with the 'vascular depression' hypothesis. Longitudinal studies are needed to clarify the time course of these relationships, in particular, whether modifying DWML alters the natural history of depression.

The stress system in the human brain in depression and neurodegeneration

Corticotropin-releasing hormone (CRH) plays a central role in the regulation of the hypothalamic-pituitary-adrenal (HPA)-axis, i.e., the final common pathway in the stress response. The action of CRH on ACTH release is strongly potentiated by vasopressin, that is co-produced in increasing amounts when the hypothalamic paraventricular neurons are chronically activated. Whereas vasopressin stimulates ACTH release in humans, oxytocin inhibits it. ACTH release results in the release of corticosteroids from the adrenal that, subsequently, through mineralocorticoid and glucocorticoid receptors, exert negative feedback on, among other things, the hippocampus, the pituitary and the hypothalamus. The most important glucocorticoid in humans is cortisol, present in higher levels in women than in men. During aging, the activation of the CRH neurons is modest compared to the extra activation observed in Alzheimer's disease (AD) and the even stronger increase in major depression. The HPA-axis is hyperactive in depression, due to genetic factors or due to aversive stimuli that may occur during early development or adult life. At least five interacting hypothalamic peptidergic systems are involved in the symptoms of major depression. Increased production of vasopressin in depression does not only occur in neurons that colocalize CRH, but also in neurons of the supraoptic nucleus (SON), which may lead to increased plasma levels of vasopressin, that have been related to an enhanced suicide risk. The increased activity of oxytocin neurons in the paraventricular nucleus (PVN) may be related to the eating disorders in depression. The suprachiasmatic nucleus (SCN), i.e., the biological clock of the brain, shows lower vasopressin production and a smaller circadian amplitude in depression, which may explain the sleeping problems in this disorder and may contribute to the strong CRH activation. The hypothalamo-pituitary thyroid (HPT)-axis is inhibited in depression. These hypothalamic peptidergic systems, i.e., the HPA-axis, the SCN, the SON and the HPT-axis, have many interactions with aminergic systems that are also implicated in depression. CRH neurons are strongly activated in depressed patients, and so is their HPA-axis, at all levels, but the individual variability is large. It is hypothesized that particularly a subgroup of CRH neurons that projects into the brain is activated in depression and induces the symptoms of this disorder. On the other hand, there is also a lot of evidence for a direct involvement of glucocorticoids in the etiology and symptoms of depression. Although there is a close association between cerebrospinal fluid (CSF) levels of CRH and alterations in the HPA-axis in depression, much of the CRH in CSF is likely to be derived from sources other than the PVN. Furthermore, a close interaction between the HPA-axis and the hypothalamic-pituitary-gonadal (HPG)-axis exists. Organizing effects during fetal life as well as activating effects of sex hormones on the HPA-axis have been reported. Such mechanisms may be a basis for the higher prevalence of mood disorders in women as compared to men. In addition, the stress system is affected by changing levels of sex hormones, as found, e.g., in the premenstrual period, ante- and postpartum, during the transition phase to the menopause and during the use of oral contraceptives. In depressed women, plasma levels of estrogen are usually lower and plasma levels of androgens are increased, while testosterone levels are decreased in depressed men. This is explained by the fact that both in depressed males and females the HPA-axis is increased in activity, parallel to a diminished HPG-axis, while the major source of androgens in women is the adrenal, whereas in men it is the testes. It is speculated, however, that in the etiology of depression the relative levels of sex hormones play a more important role than their absolute levels. Sex hormone replacement therapy indeed seems to improve mood in elderly people and AD patients. Studies of rats have shown that high levels of cumulative corticosteroid exposure and rather extreme chronic stress induce neuronal damage that selectively affects hippocampal structure. Studies performed under less extreme circumstances have so far provided conflicting data. The corticosteroid neurotoxicity hypothesis that evolved as a result of these initial observations is, however, not supported by clinical and experimental observations. In a few recent postmortem studies in patients treated with corticosteroids and patients who had been seriously and chronically depressed no indications for AD neuropathology, massive cell loss, or loss of plasticity could be found, while the incidence of apoptosis was extremely rare and only seen outside regions expected to be at risk for steroid overexposure. In addition, various recent experimental studies using good stereological methods failed to find massive cell loss in the hippocampus following exposure to stress or steroids, but rather showed adaptive and reversible changes in structural parameters after stress. Thus, the HPA-axis in AD is only moderately activated, possibly due to the initial (primary) hippocampal degeneration in this condition. There are no convincing arguments to presume a causal, primary role for cortisol in the pathogenesis of AD. Although cortisol and CRH may well be causally involved in the signs and symptoms of depression, there is so far no evidence for any major irreversible damage in the human hippocampus in this disorder.

Dementia associated with psychiatric disorders

Functional psychiatric disorders are associated with a variety of cognitive deficits and, in some instances, severe cognitive impairment. This paper reviews the cognitive profile of patients with schizophrenia, depression, bipolar and anxiety disorders, as well as the longitudinal course and clinical outcome of the cognitive impairment associated with these conditions. The paper also discusses some of the mechanisms that may contribute to the expression of the cognitive deficits in these disorders and their potential relationship with common causes of dementia.

Neuropathologic correlates of late-onset major depression

Late life major depression (LLMD) is frequently associated with cognitive impairment, and increases the risk for subsequent dementia. Cerebrovascular disease, Alzheimer's disease (AD), and dementia with Lewy bodies (DLB) have all been hypothesized to contribute to this increased risk, though prospective studies have yet to examine these hypotheses with autopsy confirmation of the clinical diagnoses. The aim of this study is to examine the rates of cerebrovascular, AD, and DLB pathology among the first 10 participants in an LLMD brain tissue donation program. Subjects' psychiatric diagnoses and cognitive status were prospectively determined during their participation in clinical research protocols of the Intervention Research Center for Late Life Mood Disorders. After death, final clinical diagnoses were made using all clinical information, while blind to neuropathologic diagnoses. Neuropathologic assessments were conducted blind to final clinical diagnoses. Rates of neuropathology were compared with those in a cohort of subjects with dementia, without a history of LLMD, participating in an Alzheimer Disease Research Center. Seven (70%) subjects had evidence of onset of a dementia prior to death. LLMD with dementia was significantly associated with a neuropathologic diagnosis of AD. Cerebrovascular disease and DLB pathology were also frequent in the LLMD subjects with dementia, and were found in an LLMD subject without dementia. Rates of AD, DLB, and cerebrovascular disease were similar to those in the comparison subjects. These preliminary findings suggest that AD is the predominant neuropathologic condition in LLMD subjects with dementia. Further assessment of the role of comorbid cerebrovascular disease and comorbid DLB is needed.

Neuronal number, volume, and apoptosis of the left dentate gyrus of chronically stressed pigs correlate negatively with basal saliva cortisol levels

Although the consequences of stress and hypercortisolemia for the rodent hippocampal dentate gyrus (DG) are well known, little is known about other species. For pigs, tethered housing represents a well-established chronic stressor that shares many similarities with restraint paradigms, as evidenced by profound changes in behavior and autonomic and endocrine dysfunction, including flattened cortisol rhythms and hypercortisolemia--all conditions that may threaten hippocampal viability in rat. Here, we studied structural parameters of the porcine DG after 5 months of tethered housing in relation to basal saliva cortisol measured antemortem. We further investigated whether any neuropathology or alterations in apoptosis had occurred in the left hippocampal hemisphere. Stereological analysis revealed high correlations between DG volume and neuron number in individual animals in both hemispheres. Within individual animals, neuron numbers of the left and right lobes were not correlated. Notably, basal cortisol was negatively correlated with volume and neuron number of the left, but not the right DG. Although obvious neuropathology was absent, apoptosis was present in DG and alveus and less so in CA areas. Despite the short window of time during which apoptosis is detectable, their stereologically estimated numbers in the DG, but not in other regions, were negatively correlated with cortisol. In conclusion, our data indicate for the first time a profound lateralization in the relationship between DG structure, apoptosis, and basal cortisol after stress in pigs. Five months of chronic stress failed to induce lasting neuropathology. Although accumulating changes in apoptosis could have contributed to the structural DG alterations, further studies should reveal whether stress has been instrumental, or whether the differences between animals were present from birth onward. The present lateralization after stress is, however, consistent with lateralized hippocampal volume changes in stress-related human disorders and suggests that these effects are not limited to this species alone.

APOE is associated with age-of-onset, but not cognitive functioning, in late-life depression

OBJECTIVE

There is a recognized but poorly understood relationship between late-life depression (LLD) and progressive dementia. Both cognitive impairment co-occurring with LLD and a late age-of-onset of first lifetime depressive episode appear to be associated with subsequent progressive dementia. A history of major depression, especially when the first onset occurs in late-life, has been identified as a risk factor for Alzheimer's disease (AD). The major genetic risk factor for sporadic AD is carrying one or more apolipoprotein E4 (APOE4) alleles. We hypothesized that the association between LLD and dementia risk would be mediated by APOE4, specifically that APOE4 allele frequency would be associated with cognitive impairment and later age-of-depression-onset. We also predicted that APOE4 allele frequency would be increased among subjects with LLD.

METHODS

We compared the distribution of APOE2, APOE3, and APOE4 alleles in groups of LLD (n=160), AD (n=568) and elderly control (EC; n=156) subjects.

RESULTS

The allele distribution of the cognitively impaired LLD subgroup was not different from either the cognitively normal subgroup or the EC group but was different from the AD group. However, mean age-of-onset of depression in APOE4 carriers (51.4+/-20.7) was significantly lower than non-carriers (58.8+/-16.8). The allele distribution in LLD overall was significantly different from the AD but not the EC group.

CONCLUSIONS

The finding that neither LLD, accompanying cognitive impairment, nor late age-of-onset was associated with an increased APOE4 allele frequency suggests that LLD acts as a risk factor for developing AD as well as non-AD dementia through mechanisms independent of APOE4. The unexpected finding that age-of-onset of LLD was significantly reduced in APOE4 carriers is similar to the association between APOE4 and age-of-onset in AD. Replication of the association of APOE4 with earlier age-of-depression-onset is indicated.

Does increased platelet release of Abeta peptide contribute to brain abnormalities in individuals with depression?

Increased platelet activation with release of procoagulant factors from their alpha granules has been demonstrated in individuals with major depression. Platelet activation has also been shown to be associated with release of beta-amyloid peptides, which have been implicated in Alzheimer's disease. Thus, we are hypothesizing that sustained elevations of Abeta peptides might occur in individuals with recurrent depression. We further hypothesize that such elevations contribute to brain abnormalities in depressed individuals through the formation of neurotoxic oligomeric forms of Abeta peptides and amyloid deposition. We also propose that increased amyloid Abeta peptides from platelet activation may be a mechanism underlying the increased risk for cognitive impairment in nondepressed patients who have other reasons for such activation. If true, our hypothesis would imply that platelet inhibitors may have a role in preventing or delaying the neuronal consequences of disorders characterized by activated platelets.

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

Alzheimer's disease (AD) patients often present with concurrent major depression (MD). To investigate the reasons for this comorbidity, e.g. MD being a risk factor for AD, or both diagnoses having a common neurobiology, the temporal relationship between the first onset of AD and of MD during lifetime was investigated-57 out of 146 AD patients had a lifetime diagnosis of MD. The correlation between the ages at onset of MD and dementia was calculated. The incidence of MD in AD patients in several 5-year-intervals before and after the onset of AD was compared with the average incidence of MD in the present AD sample and with the expected incidence of MD in the general population. No significant correlation between the onset of AD and of MD could be found after controlling for age, gender and the Mini-Mental-State. However, the incidence of MD 5 years before and after the onset of AD significantly exceeded the expected incidences-MD is only partially related to AD. However, the increased incidence of MD within 5 years before and after the onset of dementia may indicate that a common neurobiological process causes cognitive decline and depression in a subsample of AD patients.

Neuropsychiatric symptoms in the dementias

PURPOSE OF REVIEW

Neuropsychiatric, or non-cognitive symptoms are increasingly recognized as manifestations of dementias.

RECENT FINDINGS

In Alzheimer's disease, recent advances have included the identification of behavioral profiles, differentiation of apathy and depression, characterization of risk factors for psychosis and its links to agitation and aggression, and an analysis of depressive symptoms in the absence of major depression. Functional neuroimaging data mainly supported the role of the anterior cingulate in apathy. The orbitofrontal and anterior cingulate tangle burden were associated with agitation, and increased orbitofrontal and mid-temporal muscarinic M2 receptors with psychosis and hallucinations. Selected genetic polymorphisms of dopamine and serotonin receptors or transporters were linked with aggression, hallucinations or psychosis. When compared with other dementias, individuals with frontotemporal dementia disclosed, as expected, different behaviors and particularly aberrant social behavior. The frequency of delusions and visual hallucinations was increased in Parkinson's disease, Parkinson's disease with dementia, and dementia with Lewy bodies, suggesting common mechanisms such as Lewy body pathology and cholinergic deficiency. The latter was supported by an improvement of these symptoms by cholinesterase inhibitors.

SUMMARY

Future research directions include both clinical and basic neuroscience investigations. The detection of early neuropsychiatric symptoms might be a marker for dementia, and the possible existence of a mild neuropsychiatric impairment syndrome should be explored. More longitudinal studies with pathological confirmation will facilitate correlations with neuropsychiatric symptoms. Functional neuroimaging and behavioral neurogenetics will permit in-vivo correlations and consequently help patient management and care.