Six-month course of mild cognitive impairment and affective symptoms in late-life depression

Putative pathological mechanisms of late-life depression and Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder that is characterized by progressive impairment in cognition and memory. AD is accompanied by several neuropsychiatric symptoms, with depression being the most prominent. Although depression has long been known to be associated with AD, controversial findings from preclinical and clinical studies have obscured the precise nature of this association. However recent evidence suggests that depression could be a prodrome or harbinger of AD. Evidence indicates that the major central serotonergic nucleus-the dorsal raphe nucleus (DRN)-shows very early AD pathology: neurofibrillary tangles made of hyperphosphorylated tau protein and degenerated neurites. AD and depression share common pathophysiologies, including functional deficits of the serotonin (5-HT) system. 5-HT receptors have modulatory effects on the progression of AD pathology i.e., reduction in Aβ load, increased hyper-phosphorylation of tau, decreased oxidative stress etc. Moreover, preclinical models show a role for specific channelopathies that result in abnormal regional activational and neuroplasticity patterns. One of these concerns the pathological upregulation of the small conductance calcium-activated potassium (SK) channel in corticolimbic structure. This has also been observed in the DRN in both diseases. The SKC is a key regulator of cell excitability and long-term potentiation (LTP). SKC over-expression is positively correlated with aging and cognitive decline, and is evident in AD. Pharmacological blockade of SKCs has been reported to reverse symptoms of depression and AD. Thus, aberrant SKC functioning could be related to depression pathophysiology and diverts its late-life progression towards the development of AD. We summarize findings from preclinical and clinical studies suggesting a molecular linkage between depression and AD pathology. We also provide a rationale for considering SKCs as a novel pharmacological target for the treatment of AD-associated symptoms.

Incidence of cognitive impairment after hypothetical interventions on depression, nighttime sleep duration, and leisure activity engagement among older Chinese adults: An application of the parametric g-formula

Background

Cognitive impairment is an age-relevant intermediate stage where cognition declines to a state between the normal aging process and dementia. Earlier studies reported that depression, inappropriate nighttime sleep duration (NSD), and limited leisure activity engagement are cognitive impairment risk factors among older adults. Thus, we postulated that interventions on depression, sleep duration, and leisure activity engagement can reduce cognitive impairment risk. However, no earlier research ever explored this.

Methods

The data of 4,819 respondents aged 60 years and above, without cognitive impairment at baseline and with no prior history of memory-related diseases, including Alzheimer's disease, Parkinson's disease, and encephalatrophy, were obtained from the China Health and Retirement Longitudinal Study (CHARLS) between 2011 and 2018. The parametric g-formula, an analytic tool for estimating standardized outcome distributions using covariate (exposure and confounders)-specific estimates of the outcome distribution, was used to estimate 7-year cumulative cognitive impairment risks among older Chinese adults, under independent hypothetical interventions on depression, NSD, and leisure activity engagement, which was subdivided into social activity (SA) and intellectual activity (IA) for the different intervention combinations.

Results

The observed cognitive impairment risk was 37.52%. Independent intervention on IA was the most effective factor in reducing incident cognitive impairment, with a risk ratio (RR) of 0.75 (95% confidence interval [CI]: 0.67-0.82), followed by depression (RR: 0.89, 95% CI: 0.85-0.93) and NSD (RR: 0.88, 95% CI: 0.80-0.95). The joint intervention combining depression, NSD, and IA interventions could reduce the risk by 17.11%, with an RR of 0.56 (95% CI: 0.48-0.65). In subgroup analyses, independent interventions on depression and IA had analogously significant effects on men and women. However, interventions on depression and IA had stronger effects on literate than illiterate individuals.

Conclusions

Hypothetical interventions on depression, NSD, and IA reduced cognitive impairment risks among older Chinese adults, both independently and jointly. The findings of the present study suggest that the intervention measures on depression, inappropriate NSD, limited intellectual activities, and their combination may prove to be effective strategies for preventing cognitive impairment among older adults.

Effect of White Matter Hyperintensities on Daily Function via Depressive Symptoms: A Longitudinal Study in Patients With Dementia Including Alzheimer's Disease and Subcortical Ischemic Vascular Dementia

OBJECTIVE

This study aimed to investigate the mediation effect of depressive symptoms on the relationship between white matter hyperintensities and the basic activities of daily living (BADL) using an integrated approach to overcome the limitations of previous studies and examine the relationship among the three variables simultaneously.

METHODS

We performed structural equation modeling using cross-sectional data from 497 Alzheimer's disease (AD), AD with small vessel disease, and subcortical ischemic vascular dementia patients enrolled in the Clinical Research for Dementia of South Korea registry who were diagnosed with mild-to-moderate dementia. Periventricular white matter hyperintensities (PWMHs) and deep white matter hyperintensities (DWMHs) were visualized separately at baseline using magnetic resonance imaging. Depressive symptoms were assessed using the Korean Form of the Geriatric Depression Scale at the follow-up assessment conducted after 1 year. BADL were assessed using the Barthel Index at the follow-up assessment conducted after 2 years.

RESULTS

The direct and indirect effects of DWMHs on the BADL as mediated via depression were significant. However, neither the direct effect of PWMHs on the BADL nor the indirect effect of PWMHs on the BADL via depression were significant.

CONCLUSION

This study presented a mediation model that included a longitudinal developmental pathway from DWMHs to deterioration in the BADL mediated via depressive symptoms. Moreover, the mediation model of depressive symptoms could not be applied to the longitudinal developmental pathway from DWMHs to the deterioration in BADL.

Characterizing Heterogeneity in Neuroimaging, Cognition, Clinical Symptoms, and Genetics Among Patients With Late-Life Depression

Importance

Late-life depression (LLD) is characterized by considerable heterogeneity in clinical manifestation. Unraveling such heterogeneity might aid in elucidating etiological mechanisms and support precision and individualized medicine.

Objective

To cross-sectionally and longitudinally delineate disease-related heterogeneity in LLD associated with neuroanatomy, cognitive functioning, clinical symptoms, and genetic profiles.

Design, Setting, and Participants

The Imaging-Based Coordinate System for Aging and Neurodegenerative Diseases (iSTAGING) study is an international multicenter consortium investigating brain aging in pooled and harmonized data from 13 studies with more than 35 000 participants, including a subset of individuals with major depressive disorder. Multimodal data from a multicenter sample (N = 996), including neuroimaging, neurocognitive assessments, and genetics, were analyzed in this study. A semisupervised clustering method (heterogeneity through discriminative analysis) was applied to regional gray matter (GM) brain volumes to derive dimensional representations. Data were collected from July 2017 to July 2020 and analyzed from July 2020 to December 2021.

Main Outcomes and Measures

Two dimensions were identified to delineate LLD-associated heterogeneity in voxelwise GM maps, white matter (WM) fractional anisotropy, neurocognitive functioning, clinical phenotype, and genetics.

Results

A total of 501 participants with LLD (mean [SD] age, 67.39 [5.56] years; 332 women) and 495 healthy control individuals (mean [SD] age, 66.53 [5.16] years; 333 women) were included. Patients in dimension 1 demonstrated relatively preserved brain anatomy without WM disruptions relative to healthy control individuals. In contrast, patients in dimension 2 showed widespread brain atrophy and WM integrity disruptions, along with cognitive impairment and higher depression severity. Moreover, 1 de novo independent genetic variant (rs13120336; chromosome: 4, 186387714; minor allele, G) was significantly associated with dimension 1 (odds ratio, 2.35; SE, 0.15; P = 3.14 ×108) but not with dimension 2. The 2 dimensions demonstrated significant single-nucleotide variant-based heritability of 18% to 27% within the general population (N = 12 518 in UK Biobank). In a subset of individuals having longitudinal measurements, those in dimension 2 experienced a more rapid longitudinal change in GM and brain age (Cohen f2 = 0.03; P = .02) and were more likely to progress to Alzheimer disease (Cohen f2 = 0.03; P = .03) compared with those in dimension 1 (N = 1431 participants and 7224 scans from the Alzheimer's Disease Neuroimaging Initiative [ADNI], Baltimore Longitudinal Study of Aging [BLSA], and Biomarkers for Older Controls at Risk for Dementia [BIOCARD] data sets).

Conclusions and Relevance

This study characterized heterogeneity in LLD into 2 dimensions with distinct neuroanatomical, cognitive, clinical, and genetic profiles. This dimensional approach provides a potential mechanism for investigating the heterogeneity of LLD and the relevance of the latent dimensions to possible disease mechanisms, clinical outcomes, and responses to interventions.

A reliable global cognitive decline and cortisol as an associated risk factor for patients with late-life depression in the short term: A 1-year prospective study

BACKGROUND

Late-life depression is a risk factor of dementia. It may increase the risk of reliable cognitive decline in the short term, and its associated risk factors remain unclear. Cortisol level may be one of the important predictors.

OBJECTIVES

To estimate whether patients with late-life depression are at an increased risk for reliable global cognitive declines in 1 year, and explore associated risk factors predicting cognitive declines.

METHODS

This prospective 1-year follow-up study involved 148 participants (67 with late-life depression and 81 normal elderly). Global cognitive function was assessed by the Mini-Mental State Examination (MMSE). The reliable global cognitive decline was defined by the reliable change index (RCI) of the MMSE. Factors related to cognitive function (e.g., age, gender, education, duration of depression and severity of depression) were obtained. Serum cortisol levels were measured at baseline.

RESULTS

At the 1-year follow-up assessment, 19 patients with late-life depression (28.4%) showed reliable global cognitive declines, a risk that was 6.4 times (95% CIs = 1.3-31.1, p = 0.021) higher than that of normal elderly. Elevated serum cortisol levels and older age were associated with the risk of cognitive decline that was 1.6- and 1.2-times higher (95% CIs = 1.07-2.5, p = 0.02, and 95% CIs = 1.04-1.4, p = 0.01 respectively).

LIMITATIONS

Serum cortisol levels were measured only in the morning.

CONCLUSIONS

Late-life depression is associated with a greatly increased risk of reliable cognitive decline in short term. Cortisol dysregulation may contribute to the pathology of cognitive decline.

Current sleep disturbance in older people with a lifetime history of depression is associated with increased connectivity in the Default Mode Network

BACKGROUND

The present study investigated Default Mode Network (DMN) functional connectivity in subjects with a lifetime history of major depression, comparing those with and without current sleep disturbance. Controls were included to assess DMN abnormalities specific to depression.

METHODS

A total of 93 adults aged 50 years and over were recruited from the Healthy Brain Ageing Clinic at the Brain and Mind Centre, Sydney, Australia. The sample comprised two groups, including 22 controls and 71 participants with a lifetime history of DSM-IV major depression (with depressive episode current or remitted). 52 of those with a lifetime history of depression also met criteria for Mild Cognitive Impairment (MCI). Participants underwent resting-state fMRI along with comprehensive psychiatric, neuropsychological, and medical assessment. Subjective sleep quality was assessed via the Pittsburgh Sleep Quality Index (PSQI). Sleep disturbance was defined as a PSQI score > 5. A total of 68% (n = 48) of cases with a lifetime history of depression met criteria for sleep-disturbance. DMN functional connectivity was assessed via ROI-to-ROI analyses.

RESULTS

Relative to controls, those with lifetime major depression demonstrated significantly increased functional connectivity between the ventromedial prefrontal cortex and the temporal pole. Within the depression group (n = 48), those with current sleep disturbance had significantly increased connectivity between the anterior medial prefrontal cortex and both the parahippocampal cortex and the hippocampal formation, relative to those without sleep disturbance (n = 23). These results were present after controlling for MCI diagnosis.

CONCLUSIONS

Current sleep disturbance together with depression is associated with distinct abnormalities in DMN functioning incorporating regions responsible for self-reflection and declarative memory processes. Impaired sleep is associated with increased connectivity between these regions. Future studies may augment these findings with complementary imaging techniques including cortical thickness and diffusion tensor imaging, as well as high density electroencephalogram recording.

Electroconvulsive therapy and age: Age-related clinical features and effectiveness in treatment resistant major depressive episode

OBJECTIVE

This study was aimed to compare clinical features, treatments outcomes and tolerability between young (18-45 years), middle age (46-64 years) and old (≥ 65 years) patients treated with bilateral ECT for treatment resistant major depressive episode.

METHOD

402 patients were evaluated 1 day prior to ECT and a week after the treatment termination using the Clinical Global Impression Scale (CGI), the Hamilton Rating Scale for Depression-17 items (HAM-D-17), the Brief Psychiatric Rating Scale (BPRS), the Young Mania Rating Scale (YMRS) and the Mini Mental State Examination (MMSE). Response was defined as a reduction of at least 50% from baseline on the HAM-D-17 score. Remission was defined as a score ≤ 7 on the HAM-D-17 at the final evaluation.

RESULTS

Rates of response were not statistically different in the three groups (69.6% in old versus 63.5% in young and 55.5% in middle age groups). No significant differences were also observed in the proportions of remitters between the age groups (31.4% in young group, 27.7% in middle age group and 29.3% in old group). One week after the end of the ECT course the middle and old age groups showed a statistically significant increase in the MMSE score compared to baseline. We did not find significant differences between the three age groups in rates of premature drops-out due to ECT-related side effects.

CONCLUSION

Our data support the use of ECT in elderly patients with treatment-resistant major depressive episode, with rates of response around 70% and effectiveness being independent from age. In the old age group the baseline cognitive impairment improved after ECT and no life-threatening adverse event was detected.

A Systematic Review of the Measurement of Function in Late-Life Depression

Recovery of everyday premorbid function is a primary goal in the treatment of depression. Measurement of function is an important part of achieving this goal. A multitude of scales have been used to measure function in depression, reflecting the complex, multifaceted nature of functioning. Currently, however, there are no evidence-based guidelines to assist the researcher or clinician in deciding which instruments are best suited to measure function in late-life depression (LLD). Thus, the aims of this study are to 1) systematically review and identify the instrumental activities of daily living and social functioning assessment instruments used in the LLD literature; 2) identify and appraise the measurement properties of these instruments; and 3) suggest factors for LLD researchers and clinicians to consider when selecting functional assessment instruments and make pertinent recommendations. We performed a systematic review of MEDLINE and CINAHL to identify studies that i) incorporated subjects aged 60 years and older with a depressive disorder, and ii) measured instrumental activities of daily living and/or social functioning. Our search yielded 21 functional assessment instruments. Only two of these instruments, the 36-Item Short Form Survey and the Performance Assessment of Self-Care Skills, have formal validation data in LLD. Four additional instruments, although not formally validated, have relevant data regarding their measurement properties. The primary finding of this study is that very few functional assessment instruments have been validated in LLD, and the available measurement property data are mixed; there is a need for further instrument validation in late-life depression. With this caveat in mind, we provide evidence-based suggestions for researchers and clinicians assessing functioning in LLD patients.

Utilization of healthcare services among elderly with cognitive impairment no dementia and influence of depression and anxiety: a longitudinal study

OBJECTIVES

Little objective and nationally representative data are available concerning the influence of cognitive impairment no dementia (CIND) on utilization of healthcare services. The main objective was to compare the use of healthcare services over three years, between elders with current or incident CIND and those without CIND. A second objective was to evaluate the effect of depression and anxiety.

METHODS

Cross-sectional and longitudinal data from a population-based survey of 2265 older adults living in Quebec (Canada) were used. CIND was identified using normative data for the Mini-Mental State Examination and was linked with medical records from public health insurance plan. Multinomial logistic regressions adjusted for relevant socio-demographic, social network and health-related confounders were conducted for each service. Interaction between CIND and depression/anxiety was also examined.

MAIN RESULTS

Current CIND was a predictor of longer anxiolytic/sedative/hypnotic medication use. Incident CIND led to longer hospital stay. Depression raised the likelihood of frequenting geriatricians, psychiatrists or neurologists and emergency department, but lessened the likelihood of visiting general practitioners. The addition of the psychiatric conditions to the incident CIND did not increase the likelihood of consuming antidepressants, while the incident CIND cases without psychiatric conditions increased this likelihood.

DISCUSSION

Compared to older adults without CIND, older adults with CIND have a distinct utilization of healthcare services. Multiple evaluations over many years may help to better understand the utilization of healthcare services in individuals with CIND. In the meantime, evaluations of these conditions at key moments could allow a more efficient use of health resources.

Mild Cognitive Impairment Subtypes in Older People With Depressive Symptoms: Relationship With Clinical Variables and Hippocampal Change

AIMS

To examine the rates and clinical characteristics of mild cognitive impairment (MCI) in older people with depressive symptoms and to determine the relative contribution of hippocampal volume and MCI to memory change.

METHOD

One hundred and fifty-two participants with lifetime Major Depression and remitted or mild symptoms and 28 healthy controls underwent psychiatric and neuropsychological assessments. Magnetic resonance imaging was also conducted in a subset of the patients (n = 81) and healthy controls (n = 18).

RESULTS

MCI was diagnosed in 75.7% of the patients and was associated with increasing age, medical burden, vascular risk factors, later age of depression onset and smaller hippocampi. Multiple regression showed that both hippocampal volume and MCI diagnosis mediate memory performance in depression.

CONCLUSIONS

MCI occurs in older adults with a history of depression and is not simply due to symptom severity. Memory change is linked to underlying hippocampal atrophy in this patient group.

Cognitive Behavioral Therapies in older adults with depression and cognitive deficits: a systematic review

OBJECTIVES

The objective of this study is to investigate the effectiveness of cognitive behavioral therapies (CBTs) in improving depressive symptoms, disability, and cognition in older adults with depression and cognitive deficits.

DESIGN

It was performed a systematic search for articles published between 1994 and February 2014 in the MEDLINE/Pubmed, PsycINFO, and SCIELO. The studies should have provided information about benefits after CBTs to older adults with depression and cognitive deficits.

RESULTS

Cognitive behavioral therapy focused on problem solving is the main approach studied, having better effectiveness than supportive therapy in randomized clinical trials. Significant improvements in mood and disability were consistent, although evidence of changes in cognitive measures is controversial, less studied, and limited. Nevertheless, improvements in executive functions, processing speed, and changes in patients' perspectives of problem solving skills, such as generating alternatives and decision-making, were described. Also, it would be necessary that future studies more often evaluate cognitive status of depressed elders, as well as cognitive changes after psychotherapy. It should be emphasized that there is a lack of studies in this field, and more approaches in CBTs need to be investigated to this population.

CONCLUSION

Older adults with depression and cognitive deficits can benefit from CBTs. Improvements in mood and disability are more consistent than changes in cognition, which are little studied after CBTs. It is necessary more studies in the field, as well as, to investigate more approaches in CBTs to older adults with depression and cognitive deficits.

Cognitive outcomes after psychotherapeutic interventions for major depression in older adults with executive dysfunction

OBJECTIVE

The purpose of this study was to determine the impact of psychotherapy on cognitive functioning in older adults with late-life depression (LLD) and executive dysfunction.

METHODS

Two hundred twenty-one adults aged 60 years and older participated in a randomized clinical trial comparing the efficacy of Problem Solving Therapy (PST) and Supportive Therapy (ST) for LLD. Cognitive performance on seven tests of executive functioning, verbal learning, and memory was evaluated at baseline, after 12 weeks of treatment, and at 24 weeks after the completion of treatment.

RESULTS

Performance on a measure of executive functioning with a significant information processing speed component (Stroop Color and Word Test) improved after treatment, F (1, 312) = 8.50, p = 0.002, and improved performance was associated with a reduction in depressive symptoms but not treatment type. Performance on other measures of executive functioning, verbal learning, and memory did not change significantly after 12 weeks of psychotherapy treatment.

CONCLUSION

Our results suggest that improvements in cognitive functioning after psychotherapy treatment for depression in older adults with executive dysfunction are likely focal and not distributed across all cognitive domains. Although previous analyses reported that PST was superior to ST in the treatment of depression, this analysis indicated no difference between the two treatments with regard to improvements in cognitive functioning.

Mild cognitive impairment and mood: a systematic review

This systematic review, with meta-analyses conducted where data were available, aimed to investigate the prevalence of symptoms of depression and anxiety in mild cognitive impairment (MCI), and to establish how symptoms of depression and anxiety relate to the progression from no cognitive impairment to MCI, and from MCI to dementia. Sixty studies were included in the review. Meta-analyses indicated that symptoms of depression and anxiety were more prevalent in people with MCI than in people with normal cognitive function, and increased the risk of progression from no cognitive impairment to MCI. There were mixed results regarding the effect of such symptoms on progression from MCI to dementia. The findings highlight the need for more research in this area, which can inform attempts to slow or halt the progression of cognitive impairment in later life, with resulting benefits for quality of life.

Correlates of cognitive impairment in older Vietnamese

OBJECTIVES

This study examined correlates of cognitive functioning and possible cognitive impairment among older adults living in Da Nang, Vietnam and surrounding rural areas.

METHODS

The analytic sample consisted of 489 adults, 55 and older stratified by gender, age, and residence in a rural or urban area. The sample was 46% rural, 44% women, with a mean age of 69.04. Interviews were conducted in individuals' homes by trained interviewers. The dependent variable was a Vietnamese version of the mini mental status examination (MMSE). A multiple linear regression was run with the MMSE continuous scores reflecting cognitive functioning, while a binary logistic regression was conducted with an education-adjusted cut-off score reflecting possible cognitive impairment. Age, gender, education, material hardship, depressive symptoms Center for Epidemiologic Studies - Depression Scale, war injury, head trauma, diabetes, cardiovascular and cerebrovascular disease conditions served as correlates, controlling for marital status and rural/urban residence.

RESULTS

About 33% of the sample scored below the standard cutoff of 23 on the MMSE. However, only 12.9% of the sample would be considered impaired using the education-adjusted cut-off score. Cognitive functioning and possible cognitive impairment as indicated by MMSE scores were significantly associated with being older, completing fewer years of education, and material hardship. Gender, depressive symptoms, and cerebrovascular disease were associated with cognitive functioning, but not cognitive impairment.

CONCLUSION

These results show that social characteristics, physical illness, and mental health are associated with cognitive functioning. The study also raises questions about the need for standardization of screening measures on Vietnamese populations.

Reduced temporal mismatch negativity in late-life depression: an event-related potential index of cognitive deficit and functional disability?

BACKGROUND

Depression in older people has been consistently linked with a variety of neurobiological brain changes. One measure of preattentive auditory processing, the mismatch negativity (MMN), has not been previously examined in late-life depression. This study examined MMN elicited by duration deviant stimuli in older people with lifetime depression, and explored its relationship with neuropsychological functioning and disability.

METHODS

Twenty-two older health-seeking patients (mean age=65.2 years) with lifetime major depressive disorder and twelve age and sex-matched control participants (mean age=64.6 years) completed detailed clinical and neuropsychological assessments and the WHO-DAS as a measure of disability. MMN amplitudes were elicited using a two-tone passive auditory oddball paradigm and measured at frontal (Fz), central (Cz) and temporal (left and right mastoid: M1 and M2, respectively) sites.

RESULTS

Patients with depression demonstrated reduced mean MMN amplitude at temporal (M1, t=3.1, p<0.01; M2, t=3.8, p<0.01), but not fronto-central sites. Reduced temporal MMN amplitudes did not relate to depressive symptom severity, but were associated with reduced semantic fluency and greater self-rated functional disability.

LIMITATIONS

The contribution of depressive symptom 'state' and medications on MMN need to be considered.

CONCLUSIONS

Reduced mean amplitudes of mastoid MMN in older patients with lifetime depression may reflect underlying brain changes. This preattentive marker relates to neuropsychological probes of frontotemporal circuits, and importantly, is associated with disability. Longitudinal analysis of MMN in this group will determine its predictive utility as a biomarker for ongoing cognitive decline and illness chronicity.

Neural correlates of the interactive relationship between memory deficits and depressive symptoms in nondemented elderly: resting fMRI study

Prospective studies have shown an association between depressive symptoms and cognitive impairment among older adults. However, the neural correlates of this relationship are poorly understood. Our aim was to examine whether interactive effects of memory deficits and depressive symptoms are present in the memory-associated functional networks, in nondemented elderly subjects. Fifteen subjects with amnestic mild cognitive impairment (aMCI) and 20 age-matched normal (CN) elderly subjects participated in this cross-sectional study. Resting-state functional connectivity MRI (R-fMRI) measured the hippocampal functional connectivity (HFC) alterations between the two groups. Voxelwise linear regression analysis was performed to correlate hippocampal network strength with the Rey Auditory Verbal Learning Test delayed recall and the Geriatric Depression Scale scores, after adjusting for age and group effects. Poorer memory performance was associated with decreased positively correlated HFC connectivity in the specific frontal lobe and default mode network (DMN) structures. Poorer memory performance also was associated with decreased anticorrelated HFC connectivity in the bilateral inferior parietal and right dorsolateral prefrontal cortices. In contrast, greater depressive symptom severity was associated with increased HFC connectivity in several frontal lobes and DMN regions. Depressive symptoms and memory functions had interactive effects on the HFC, in the frontal, temporal, and PCC structures. Our findings suggest that the R-fMRI technique can be used to examine the changes in functional neural networks where memory deficits and depressive symptoms coexist in the geriatric population.

The pattern and course of cognitive impairment in late-life depression

BACKGROUND

Cognitive deficits persist despite clinical recovery in subjects with late-life depression, but more needs to be known about their longer-term outcome and factors affecting their course. To investigate this, we followed the pattern of cognitive impairments over time and examined the effects of current mood, remission status, age of depression onset and antidepressant (AD) treatment on these deficits.

METHOD

Sixty-seven subjects aged > or = 60 years with DSM-IV major depressive disorder and 36 healthy comparison subjects underwent tests of global cognition, memory, executive functioning and processing speed at baseline, 6 and 18 months, with some subjects tested again after 4 years. z scores were compared between groups, with analyses of clinical factors that may have influenced cognitive performance in depressed subjects.

RESULTS

Half of the patients exhibited a generalized cognitive impairment (GCI) that persisted after 18 months. Patients performed worse across all cognitive domains at all time points, without substantial variability due to current mood, remission status or AD treatment. Late age of onset was associated significantly with decline in memory and executive functioning. Impaired processing speed may be a partial mediator of some deficits, but was insufficient to explain differences between patients and controls. Four-year follow-up data suggest impairments persist, but do not further decline.

CONCLUSIONS

Cognitive deficits in late-life depression persist up to 4 years, affect multiple domains and are related to trait rather than state effects. Differences in severity and course between early and late onset depression suggest different pathogenic processes.

The Wisconsin Card Sorting Test and the N-back test in mild cognitive impairment and elderly depression

The aim of this study was to assess cognitive functions in 30 non-depressed patients with mild cognitive impairment (MCI), compared with 30 age-, gender- and education-matched patients with acute depressive episode, and with 30 healthy subjects. Neuropsychological assessment included the Mini Mental State Examination (MMSE), memory tests as well as the Wisconsin Card Sorting Test (WCST) and the N-back test. Patients with MCI obtained significantly worse results on all domains of the WCST and the N-back test compared to both depressed and healthy subjects. Depressed patients showed significantly worse performance than controls on most scores. In the MCI group, no association with MMSE was found with any of WCST domains, or with reaction time in the N-back test. Three tests, WCST-P, N-back %CORR and WCST 1st CAT obtained highest ranks (>90) as predictors for differentiating between groups. The results suggest a usefulness of employing WCST and N-back tests for a neuropsychological evaluation of patients with MCI.

Late-life depression, mild cognitive impairment, and dementia: possible continuum?

Clinical and epidemiologic research has focused on the identification of risk factors that may be modified in predementia syndromes, at a preclinical and early clinical stage of dementing disorders, with specific attention to the role of depression. Our goal was to provide an overview of these studies and more specifically to describe the prevalence and incidence of depression in individuals with mild cognitive impairment (MCI), the possible impact of depressive symptoms on incident MCI, or its progression to dementia and the possible mechanisms behind the observed associations. Prevalence and incidence of depressive symptoms or syndromes in MCI vary as a result of different diagnostic criteria and different sampling and assessment procedures. The prevalence of depression in individuals with MCI was higher in hospital-based studies (median: 44.3%, range: 9%-83%) than in population-based studies (median: 15.7%, range: 3%-63%), reflecting different referral patterns and selection criteria. Incidence of depressive symptoms varied from 11.7 to 26.6/100 person-years in hospital-based and population-based studies. For depressed normal subjects and depressed patients with MCI, the findings on increased risk of incident MCI or its progression to dementia were conflicting. These contrasting findings suggested that the length of the follow-up period, the study design, the sample population, and methodological differences may be central for detecting an association between baseline depression and subsequent development of MCI or its progression to dementia. Assuming that MCI may be the earliest identifiable clinical stage of dementia, depressive symptoms may be an early manifestation rather than a risk factor for dementia and Alzheimer disease, arguing that the underlying neuropathological condition that causes MCI or dementia also causes depressive symptoms. In this scenario, at least in certain subsets of elderly patients, late-life depression, MCI, and dementia could represent a possible clinical continuum.

Donepezil delays progression to AD in MCI subjects with depressive symptoms

OBJECTIVE

To determine whether the presence of depression predicts higher rate of progression to Alzheimer disease (AD) in patients with amnestic mild cognitive impairment (aMCI) and whether donepezil treatment beneficially affect this relationship.

METHODS

The study sample was composed of 756 participants with aMCI from the 3-year, double-blind, placebo-controlled Alzheimer's Disease Cooperative Study drug trial of donepezil and vitamin E. Beck Depression Inventory (BDI) was used to assess depressive symptoms at baseline and participants were followed either to the end of study or to the primary endpoint of progression to probable or possible AD.

RESULTS

Cox proportional hazards regression, adjusted for age at baseline, gender, apolipoprotein genotype, and NYU paragraph delayed recall score, showed that higher BDI scores were associated with progression to AD (p = 0.03). The sample was stratified into depressed (BDI score > or =10; n = 208) and nondepressed (BDI <10; n = 548) groups. Kaplan-Meier analysis showed that among the depressed subjects, the proportion progressing to AD was lower for the donepezil group than the combined vitamin E and placebo groups at 1.7 years (p = 0.023), at 2.2 years (p = 0.025), and remained marginally lower at 2.7 years (p = 0.070). The survival curves among the three treatment groups did not differ within the nondepressed participants.

CONCLUSIONS

Results suggest that depression is predictive of progression from amnestic mild cognitive impairment (aMCI) to Alzheimer disease (AD) and treatment with donepezil delayed progression to AD among depressed subjects with aMCI. Donepezil appears to modulate the increased risk of AD conferred by the presence of depressive symptoms.

Neuropsychiatric manifestations in mild cognitive impairment: a systematic review of the literature

BACKGROUND

Mild cognitive impairment (MCI) is an etiologically heterogeneous condition that is characterized by cognitive changes without impairment of activities of daily living and insufficient to represent dementia. MCI is an important risk state for dementia. Neuropsychiatric symptoms may be present in MCI.

METHODS

We executed a PubMed search for articles on the neuropsychiatric manifestations in MCI and reviewed their findings.

RESULTS

Behavioral abnormalities are reported in 35-75% of MCI patients with the most common being depression, apathy, anxiety and irritability. The observed variability in symptom prevalence can be explained by the different sampling methods, MCI diagnostic criteria and behavioral instruments used. There is a compelling body of evidence that MCI patients with behavioral features are more prone to develop Alzheimer's disease (AD) than patients without these features.

CONCLUSIONS

Neuropsychiatric symptoms are common features of MCI. The behavioral changes observed in MCI are similar to those of AD and may help identify the subgroup of MCI patients with prodromal AD. Large prospective longitudinal studies would greatly contribute to our understanding of the epidemiology, diagnostic and prognostic value of the neuropsychiatric features in MCI.

Geriatric depression and cognitive impairment

Cognitive impairment is common in geriatric depression, and depressed individuals with co-morbid cognitive impairment are at increased risk for a number of adverse medical, psychiatric and cognitive outcomes. This review focuses on clinical issues surrounding the co-occurrence of these two conditions within the context of current research. We (1) review the clinical criteria and prevalence of depression, as well as co-morbid cognitive impairment, (2) discuss factors associated with persistent cognitive impairment in depression, including dementia, and (3) review research relevant to the assessment and treatment of cognitive impairment and dementia in the context of depression. We conclude that current research on depression and cognition can inform clinical decisions that reduce the occurrence of adverse outcomes. Clinicians are encouraged to develop proactive approaches for treatment, which may include combinations of pharmacological and psychotherapeutic interventions.

Neuropsychiatric symptoms are associated with progression from mild cognitive impairment to Alzheimer's disease

BACKGROUND

Neuropsychiatric disturbances are common in mild cognitive impairment (MCI). Depression and apathy may identify a subset of MCI subjects at higher risk of progression to Alzheimer's disease (AD). However, it remains uncertain whether a broader spectrum of psychopathology is associated with progression to AD.

METHODS

Fifty-one MCI subjects were assessed for neuropsychiatric symptoms using the Neuropsychiatric Inventory. Subjects were followed for an average of 2 years. Twelve subjects (23.5%) progressed from MCI to possible/probable AD and 39 subjects (76.5%) remained stable or improved. Baseline Neuropsychiatric Inventory indices were compared between groups.

RESULTS

Subjects progressing to AD had a significantly higher prevalence of psychopathology than subjects who remained stable or improved (100 vs. 59%). Depression (67 vs. 31%) and apathy (50 vs. 18%) were more common in subjects who were later diagnosed with AD. After statistical adjustments for other baseline demographic variables, these specific symptoms were less robust predictors of progression to AD than the presence of any psychopathology.

CONCLUSIONS

These findings suggest that neuropsychiatric symptoms in MCI are a predictor of progression to AD. Depression and apathy appear to be most useful for identifying MCI subjects at highest risk of developing dementia.

Contribution of depression to cognitive impairment and dementia in older adults

BACKGROUND

The objective of this review is to provide information for clinicians regarding current research and opinions on the association of depression to conditions of cognitive impairment and dementia. We also intend to integrate this current research and thinking into strategies for the assessment and treatment of depression in the context of cognitive impairment.

REVIEW SUMMARY

Depression is highly prevalent in mild cognitive impairment and most dementias. It may be a risk factor for the subsequent development of dementia and in some conditions may be a prodromal symptom. It is important to detect and effectively treat depression because the comorbidity of depression and cognitive impairment is associated with greater cognitive and functional decline and higher rates of institutionalization. Depression often can be differentiated from Alzheimer disease and other dementias based on characteristics of clinical history and presentation. Screening of depression and cognitive impairment will help characterize the presence and severity of these conditions, but limitations in screening approaches may necessitate comprehensive assessment in complex cases where differential diagnosis is important to treatment planning.

CONCLUSION

Although depression and cognitive impairment are important issues in the treatment of older adults, there are particular risks when they occur together. Appropriate assessment and screening can help guide the clinician to appropriate and timely interventions. Pharmacologic and nonpharmacologic treatment approaches are both efficacious in reducing depression in cognitive impairment and dementia.

Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application

Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.