Depressive syndromes in dementia

Association of depressive symptoms and dementia among middle-aged and elderly community-dwelling adults: Results from the China Health and Retirement Longitudinal Study (CHARLS)

BACKGROUND

There has been a long-standing debate on whether depressive symptoms are associated with dementia. The aim of this study was to examine whether depressive symptoms were associated with a high risk for dementia in Chinese adults.

METHODS

A total of 13,426 Chinese adults (≥45 years old) from the China Health and Retirement Longitudinal Study (CHARLS) baseline were selected for analysis. Depressive symptoms were assessed by the Center for Epidemiologic Studies Depression Scale (CESD-10). Dementia was assessed by the Community Screening Instrument for Dementia (CSI-D). When using linear regression for sensitivity analysis, there is still a correlation between depressive symptoms and dementia.

RESULTS

Of the 13,426 respondents, the mean (SD) age was 60 (10) years old. The prevalence of depressive symptoms and dementia among participants was 38 % (n = 945) and 18.3 % (n = 2457), respectively. After fully adjusted for demographic factors, health behavior and psychological factors, living and working conditions factors, social network factors, and social policy factors, the cross-sectional analyses showed that depressive symptoms had an increased risk of dementia (OR = 1.390, 95%CI: 1.253-1.543), compared with those without depressive symptoms. In addition, sensitivity analyses of the association between depressive symptoms and dementia were unchanged when reanalyzing using linear regression.

CONCLUSIONS

In this study, depression symptoms may be associated with dementia. Regardless of whether depressive symptoms acts as a dementia risk factor or an early symptom, monitoring depressive symptoms is crucial to watch for potential dementia onset.

Can Animal Models Inform on the Relationship between Depression and Alzheimer Disease?

The focus on the β-amyloid (Aβ) peptide in clinical Alzheimer disease (AD) as well as in animal models of AD has perhaps biased our understanding of what contributes to the heterogeneity in disease onset and progression. Part of this heterogeneity could reflect the various neuropsychiatric risk factors that present with common symptomatology and can predispose the brain to AD-like changes. One such risk factor is depression. Animal models, particularly mouse models carrying variants of AD-related gene(s), many of which lead to an accumulation of Aβ, suggest that a fundamental shift in depression-related monoaminergic systems (including serotonin and noradrenaline) is a strong indicator of the altered cellular function associated with the earlier(est) stages of AD-related pathology. These changes in monoaminergic neurochemistry could provide for relevant targets for intervention in clinical AD and/or could support a polypharmacy strategy, which might include the targeting of Aβ, in vulnerable populations. Future studies must also include female mice as well as male mice in animal model studies on the relationship between depression and AD.

Saccadic eye movements in depressed elderly patients

The primary aim of this study was to characterize oculomotor performances in elderly depressed patients. The second aim was to investigate whether cognitive inhibition measured by the antisaccade task was associated with a psychomotor retardation or rather with a more specific cognitive-motor inhibition deficit. Twenty patients with a major depressive disorder and forty-seven healthy subjects performed two eye movement tasks. Saccadic reaction time and error rates were analyzed in the prosaccade task to obtain basic parameters of eye movements. Saccade latency, error rates and correction rates were evaluated in the antisaccade task to investigate inhibition capacities. Performances were impaired in patients, who exhibited a higher reaction time and error rates compared to controls. The higher time cost of inhibition suggested that the reaction time was not related to global psychomotor retardation alone. The higher time cost of inhibition could be explained by a specific alteration of inhibition processes evaluated by the antisaccade task. These changes were associated with the severity of depression. These findings provide a new perspective on cognitive inhibition in elderly depressed patients and could have important clinical implications for our understanding of critical behaviors involving deficits in inhibitory processes in the elderly.

Irritability and social isolation in dementia patients with and without depression

This study examined the prevalence of irritability and social isolation in veterans with dementia, with and without depression. Participants were diagnosed with dementia and enrolled in a dementia care-coordination and support-service intervention. Participants were interviewed and underwent assessment with the 10-item Center for Epidemiologic Studies Depression scale, a Patient Strain Measure and the Short Blessed Test. In all, of 294 participants completing interviews, 77 (26.2%) were depressed and 107 (36.4%) endorsed irritability; mean social isolation score was 1.59 ± 1.96. Irritability was significantly more likely to be present in depressed versus nondepressed participants (P < .0001), but this relationship was moderated by dementia severity. The mean social isolation score was also significantly more elevated in depressed rather than nondepressed patients (2.82 ± 1.96 vs 1.15 ± 1.76, respectively).

CONCLUSIONS

Depressed persons with dementia are significantly more likely to experience irritability and social isolation than those who are not depressed.

Alzheimer disease-related presenilin-1 variants exert distinct effects on monoamine oxidase-A activity in vitro

Monoamine oxidase-A (MAO-A) has been associated with both depression and Alzheimer disease (AD). Recently, carriers of AD-related presenilin-1 (PS-1) alleles have been found to be at higher risk for developing clinical depression. We chose to examine whether PS-1 could influence MAO-A function in vitro. Overexpression of selected AD-related PS-1 variants (wildtype, Y115H, ΔEx9 and M146V) in mouse hippocampal HT-22 cells affects MAO-A catalytic activity in a variant-specific manner. The ability of the PS-1 substrate-competitor DAPT to induce MAO-A activity in cells expressing either PS-1 wildtype or PS-1(M146V) suggests the potential for a direct influence of PS-1 on MAO-A function. In support of this, we were able to co-immunoprecipitate MAO-A with FLAG-tagged PS-1 wildtype and M146V proteins. This potential for a direct protein-protein interaction between PS-1 and MAO-A is not specific for HT-22 cells as we were also able to co-immunoprecipitate MAO-A with FLAG-PS-1 variants in N2a mouse neuroblastoma cells and in HEK293 human embryonic kidney cells. Finally, we demonstrate that the two PS-1 variants reported to be associated with an increased incidence of clinical depression [e.g., A431E and L235V] both induce MAO-A activity in HT-22 cells. A direct influence of PS-1 variants on MAO-A function could provide an explanation for the changes in monoaminergic tone observed in several neurodegenerative processes including AD. The ability to induce MAO-A catalytic activity with a PS-1/γ-secretase inhibitor should also be considered when designing secretase inhibitor-based therapeutics.

Antidepressants are a rational complementary therapy for the treatment of Alzheimer's disease

There is a high prevalence rate (30-50%) of Alzheimer's disease (AD) and depression comorbidity. Depression can be a risk factor for the development of AD or it can be developed secondary to the neurodegenerative process. There are numerous documented diagnosis and treatment challenges for the patients who suffer comorbidity between these two diseases. Meta analysis studies have provided evidence for the safety and efficacy of antidepressants in treatment of depression in AD patients. Preclinical and clinical studies show the positive role of chronic administration of selective serotonin reuptake inhibitor (SSRI) antidepressants in hindering the progression of the AD and improving patient performance. A number of clinical studies suggest a beneficial role of combinatorial therapies that pair antidepressants with FDA approved AD drugs. Preclinical studies also demonstrate a favorable effect of natural antidepressants for AD patients. Based on the preclinical studies there are a number of plausible antidepressants effects that may modulate the progression of AD. These effects include an increase in neurogenesis, improvement in learning and memory, elevation in the levels of neurotrophic factors and pCREB and a reduction of amyloid peptide burden. Based on this preclinical and clinical evidence, antidepressants represent a rational complimentary strategy for the treatment of AD patients with depression comorbidity.

Calcium-sensitive regulation of monoamine oxidase-A contributes to the production of peroxyradicals in hippocampal cultures: implications for Alzheimer disease-related pathology

Background

Calcium (Ca²⁺) has recently been shown to selectively increase the activity of monoamine oxidase-A (MAO-A), a mitochondria-bound enzyme that generates peroxyradicals as a natural by-product of the deamination of neurotransmitters such as serotonin. It has also been suggested that increased intracellular free Ca²⁺ levels as well as MAO-A may be contributing to the oxidative stress associated with Alzheimer disease (AD).

Results

Incubation with Ca²⁺ selectively increases MAO-A enzymatic activity in protein extracts from mouse hippocampal HT-22 cell cultures. Treatment of HT-22 cultures with the Ca²⁺ ionophore A23187 also increases MAO-A activity, whereas overexpression of calbindin-D28K (CB-28K), a Ca²⁺-binding protein in brain that is greatly reduced in AD, decreases MAO-A activity. The effects of A23187 and CB-28K are both independent of any change in MAO-A protein or gene expression. The toxicity (via production of peroxyradicals and/or chromatin condensation) associated with either A23187 or the AD-related β-amyloid peptide, which also increases free intracellular Ca²⁺, is attenuated by MAO-A inhibition in HT-22 cells as well as in primary hippocampal cultures.

Conclusion

These data suggest that increases in intracellular Ca²⁺ availability could contribute to a MAO-A-mediated mechanism with a role in AD-related oxidative stress.

Efficacy and safety of antidepressants for treatment of depression in Alzheimer's disease: a metaanalysis

OBJECTIVE

Depression in patients with Alzheimer's disease (AD) is common (15% to 63%) and is associated with significant morbidity and increased mortality. Our objective was to quantitatively summarize the data on the efficacy and safety of antidepressant treatment for depression complicating AD.

METHOD

We performed a metaanalysis of randomized, double-blind, placebo-controlled trials of antidepressants with a database search of the English literature (up to 2006) and a manual search of references in the retrieved articles. We extracted the proportion of subjects who responded and remitted, experienced adverse events (AEs), discontinued treatment due to AEs, or discontinued treatment for any reason. Cognition scores were also extracted.

RESULTS

We included 5 studies, which involved 82 subjects treated with antidepressants and 83 subjects who received placebo treatment. Antidepressants were superior to placebo for both treatment response (odds ratio [OR] 2.32; 95% confidence interval [CI], 1.04 to 5.16) and remission of depression (OR 2.75; 95% CI, 1.13 to 6.65). There were no significant differences between the 2 groups for change in cognition (weighted mean difference -0.71, 95% CI, -3.20 to 1.79), overall dropouts (OR 0.70; 95% CI, 0.29 to 1.66) or dropout due to AEs (OR 1.41; 95% CI 0.36 to 5.54). The numbers needed to treat for one additional AD patient to respond to antidepressant treatment were 5 (95% CI, 3 to 59) and 5 (95% CI, 2 to 24) for remission of depression.

CONCLUSIONS

Antidepressant treatment for depression in AD is efficacious, with rates of discontinuation that are comparable to placebo. Nonetheless, clinicians must be vigilant regarding the potential side effects of antidepressants in this population.

Bereavement in cognitively impaired older adults: case series and clinical considerations

The intersection of bereavement and cognitive impairment presents unique clinical challenges that have been overlooked in the literature. Cognitive impairment can interfere with normal ways of coping in the aftermath of loss. Elderly persons with cognitive impairment may have difficulty processing their loss and may even forget that their loved one has died, repeatedly asking other family members when the deceased is coming to visit. This can prove devastating for such individuals and their families, who are forced to keep reexperiencing their grief. This article examines the phenomenology of bereavement-related distress in older adults with cognitive impairment and dementia through a case series gathered from a large geriatric facility. The dilemmas in caring for bereaved elderly with cognitive difficulties and their families are highlighted, drawing attention to a vulnerable population. The purpose of this undertaking is to present a novel classification of a clinically relevant but overlooked issue as well as provide strategies for management and suggestions for future research.

Altered depression-related behavior and neurochemical changes in serotonergic neurons in mutant R406W human tau transgenic mice

Mutant R406W human tau was originally identified in frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) and causes a hereditary tauopathy that clinically resembles Alzheimer's disease (AD). In the current study, we examined the performance of R406W transgenic (Tg) mice in the forced swimming test, a test with high predictivity of antidepressant efficacy in human depression, and found an enhancement of the immobility time. In contrast, the motor function and anxiety-related emotional response of R406W Tg mice were normal. Furthermore, a selective serotonin reuptake inhibitor (SSRI), fluvoxamine (100 mg/kg, p.o.), significantly reduced this enhancement of the immobility time, whereas a noradrenaline reuptake inhibitor, desipramine, had no effect. In an in vivo microdialysis study, R406W Tg mice exhibited a significantly decreased extracellular 5-hydroxyindoleacetic acid (5-HIAA) level in the frontal cortex and also exhibited a tendency toward a decreased extracellular 5-hydroxytryptamine (5-HT) level. Moreover, fluvoxamine, which reduced the enhancement of the immobility time, significantly increased the extracellular 5-HT level in R406W Tg mice. These results suggest that R406W Tg mice exhibit changes in depression-related behavior involving serotonergic neurons and provide an animal model for investigating AD with depression.

Complexity in late-life depression: impact of confounding factors on diagnosis, treatment, and outcomes

Late-life depression is a heterogeneous syndrome. Although depression in elderly patients is highly treatable, a number of factors or confounds create complexity in its overall management. Patient factors, such as medical illness, neuropsychiatric comorbidity, and race, may interact with provider factors to make management more complex. Outcomes and services research indicate that these factors, particularly medical illness, affect whether late-life depression is appropriately detected, diagnosed, and treated. Attention to such factors must be included in an agenda for mental health services research, with emphasis on the delivery of effective treatment to elderly patients with depression and improved outcomes in clinical settings.