Cortical Thickness of the Salience Network and Change in Apathy Following Antidepressant Treatment for Late-Life Depression

OBJECTIVE

Apathy is common in late-life depression and is associated with poor response to antidepressant drugs. In depressed older adults, apathy may be characterized by neuroanatomical abnormalities of the salience network. The current study examined whether cortical thickness of select salience network structures predicted change in apathy following a 12-week treatment with escitalopram.

METHODS

A sample of 46 older adults with major depressive disorder received 12 weeks of escitalopram treatment at a daily target dose of 20 mg. All participants underwent a structural brain MRI scan at baseline, and cortical thickness was estimated in key cortical nodes of the salience network: the caudal anterior cingulate cortex and the insula. We measured baseline and post-treatment symptoms using the Apathy Evaluation Scale and the Hamilton Depression Rating Scale.

RESULTS

A thicker insula at baseline predicted reduction in apathy symptoms following 12 weeks of treatment with escitalopram, even when controlling for age, baseline depression severity and change in depressive symptoms.

CONCLUSION

Reduced insular thickness predicted residual apathetic symptoms following escitalopram treatment. These results converge with our previous findings of abnormal functional connectivity of the insular cortex in older depressed individuals with apathy. Older depressed adults with apathy may benefit from alternative treatment approaches or augmentative interventions that target abnormalities of the salience network.

Neuroanatomical Abnormalities in Older Depressed Adults With Apathy: A Systematic Review

OBJECTIVE

Apathy is a common phenomenon in late-life depression and is associated with poor outcomes. Apathy is often unrecognized in older depressed adults, and efficacious treatment options are lacking. This review provides a systematic review of the neuroanatomical abnormalities associated with apathy in late-life depression. In addition, the review summarizes the neuroimaging findings from studies of neurodegenerative and focal brain injury conditions that frequently present with apathy. The goal is to elucidate cerebral network abnormalities that give rise to apathy in older adults with mood disturbances and to inform future treatment targets.

METHOD

Systematic literature review.

RESULTS

The few studies that have directly examined the neuroanatomical abnormalities of apathy in late-life depression suggest disturbances in the anterior cingulate cortex, insula, orbital and dorsal prefrontal cortex, striatum, and limbic structures (ie, amygdala, thalamus, and hippocampus). Studies examining the neuroanatomical correlates of apathy in other aging populations are consistent with the pattern observed in late-life depression.

CONCLUSIONS

Apathy in late-life depression appears to be accompanied by neuroanatomical abnormalities in the salience and reward networks. These network findings are consistent with that observed in individuals presenting with apathy in other aging-related conditions. These findings may inform future treatments that target apathy.

Clinical and radiological characteristics of early versus late mild cognitive impairment in patients with comorbid depressive disorder

OBJECTIVE

The classification of mild cognitive impairment (MCI) continues to be debated though it has recently been subtyped into late (LMCI) versus early (EMCI) stages. Older adults presenting with both a depressive disorder (DEP) and cognitive impairment (CI) represent a unique, understudied population. Our aim was to examine baseline characteristics of DEP-CI patients in the DOTCODE trial, a randomized controlled trial of open antidepressant treatment for 16 weeks followed by add-on donepezil or placebo for 62 weeks.

METHODS/DESIGN

Key inclusion criteria were diagnosis of major depression or dysthymic disorder with Hamilton Depression Rating Scale (HAM-D) score >14, and cognitive impairment defined by MMSE score ≥21 and impaired performance on the WMS-R Logical Memory II test. Patients were classified as EMCI or LMCI based on the 1.5 SD cutoff on tests of verbal memory, and compared on baseline clinical, neuropsychological, and anatomical characteristics.

RESULTS

Seventy-nine DEP-CI patients were recruited of whom 39 met criteria for EMCI and 40 for LMCI. The mean age was 68.9, and mean HAM-D was 23.0. Late mild cognitive impairment patients had significantly worse ADAS-Cog (P < .001), MMSE (P = .004), Block Design (P = .024), Visual Rep II (P = .006), CFL Animal (P = .006), UPSIT (P = .051), as well as smaller right hippocampal volume (P = .037) compared to EMCI patients. MRI indices of cerebrovascular disease did not differ between EMCI and LMCI patients.

CONCLUSIONS

Cognitive and neuronal loss markers differed between EMCI and LMCI among patients with DEP-CI, with LMCI being more likely to have the clinical and neuronal loss markers known to be associated with Alzheimer's disease.

Computerized cognitive training and functional recovery in major depressive disorder: A meta-analysis

OBJECTIVE

Depression is common, frequently resistant to antidepressant treatment, and associated with impairments in cognition and everyday functioning. Computerized cognitive training (CCT) paradigms offer potential to improve cognition, mood and everyday functioning, but their effectiveness is not well established. The goal of this article was to conduct a systematic review and meta-analysis to determine the efficacy of CCT in depressive disorders.

METHOD

A search was conducted to identify high quality randomized controlled CCT trials per PRISMA guidelines using PsycINFO and MEDLINE with the keywords "Cognitive training" or "Cognitive remediation" or "Cognitive rehabilitation" and "Depression". 9 randomized trials for depressed adults met inclusion criteria. Effect sizes (Hedge's g) were calculated for key outcome measures of mood symptom severity, daily functioning, and cognition. A 3-level Bayesian hierarchical linear model was used to estimate effect sizes for each domain and study. Publication bias was assessed using Classic Fail Safe N's and homogeneity was evaluated using Q and I(2) indexes.

RESULTS

Significant small-moderate effects for Symptom Severity (0.43) and Daily Functioning (0.72), and moderate-large effects for Attention (0.67), Working Memory (0.72), and Global Functioning (1.05) were found. No significant effects were found for Executive Functioning or Verbal Memory. Moderator variable analysis revealed decreased effect of CCT with age. Gender and concurrent medication treatment did not affect the results.

LIMITATIONS

Small sample size, short duration, pseudo-specificity, and high heterogeneity for Verbal Memory measures.

CONCLUSIONS

CCT is associated with improvement in depressive symptoms and everyday functioning, though produces inconsistent effects on cognition.

A Meta-Analysis of Executive Dysfunction and Antidepressant Treatment Response in Late-Life Depression

OBJECTIVE

Depressed older adults with executive dysfunction (ED) may respond poorly to antidepressant treatment. ED is a multifaceted construct and different studies have measured different aspects of ED, making it unclear which aspects predict poor response. Meta-analytic methods were used to determine whether ED predicts poor antidepressant treatment response in late-life depression and to determine which domains of executive functioning are responsible for this relationship.

METHODS

A Medline search was conducted to identify regimented treatment trials contrasting executive functioning between elderly responders and nonresponders; only regimented treatment trials for depressed outpatients aged 50 and older were included. Following the most recent PRISMA guidelines, 25 measures of executive functioning were extracted from eight studies. Six domains were identified: cognitive flexibility, planning and organization, response inhibition, selective attention, verbal fluency, and the Dementia Rating Scale Initiation/Perseveration composite score (DRS I/P). Hedge's g was calculated for each measure of executive functioning. A three-level Bayesian hierarchical linear model (HLM) was used to estimate effect sizes for each domain of executive functioning.

RESULTS

The effect of planning and organization was significantly different from zero (Bayesian HLM estimate of domain effect size: 0.91; 95% CI: 0.32-1.58), whereas cognitive flexibility, response inhibition, selective attention, verbal fluency, and the DRS I/P composite score were not.

CONCLUSION

The domain of planning and organization is meaningfully associated with poor antidepressant treatment response in late-life depression. These findings suggest that therapies that focus on planning and organization may provide effective augmentation strategies for antidepressant nonresponders with late-life depression.

The external validity of MRI-defined vascular depression

OBJECTIVE

Multiple diagnostic criteria have been used to define vascular depression (VD). As a result, there are discrepancies in the clinical characteristics that have been established for the illness. The aim of this study was twofold. First, we used empirically established diagnostic criteria to determine the clinical characteristics of magnetic resonance imaging (MRI)-defined VD. Second, we assessed the agreement between a quantitative and qualitative method for identifying the illness.

METHOD

We examined the baseline clinical and neuropsychological profile of 38 patients from a larger, double-blind, randomized, 12-week clinical trial comparing nortriptyline with sertraline in depressed older adults. Ten patients met quantitative criteria for MRI-defined VD based on the highest quartile of deep white matter hyperintensity (DWMH) volume. Fourteen patients met qualitative criteria for MRI-defined VD based on a DWMH score of 2 or higher on the Fazekas' modified Coffey rating scale.

RESULTS

Age, gender, cumulative illness rating scale-geriatric (CIRS-G) score, two measures of psychomotor retardation [the psychomotor retardation item of the Hamilton Rating Scale for Depression (HRSD) as well as performance on the Purdue Pegboard], and performance on the Stroop Color/Word test (a measure of the response inhibition component of executive functioning) were significantly different between those with VD and non-VD.

CONCLUSIONS

Patients with VD have a distinct clinical and neuropsychological profile that is mostly consistent across different methods for identifying the illness. These findings support the notion that MRI-defined VD represents a unique and valid subtype of late-life depression.

Speed of processing and depression affect function in older adults with mild cognitive impairment

OBJECTIVES

To evaluate the effect of depression and cognition on function in older adults with amnestic and nonamnestic mild cognitive impairment (aMCI and nonaMCI).

DESIGN

The study uses baseline data from the National Alzheimer's Coordinating Center.

SETTING

Data were collected at multiple Alzheimer's Disease Centers in the United States.

PARTICIPANTS

The sample included a total of 3,117 individuals with MCI, mean age = 74.37 years, SD: 9.37 (aMCI, n = 2,488; non-aMCI, n = 629).

MEASUREMENTS

The 10-item Pfeffer Functional Activities Questionnaire assessed function.

RESULTS

Depressive symptoms (Geriatric Depression Scale), memory impairment (Logical Memory II), and processing speed decrements (Digit Symbol Substitution Test) were significantly associated with functional impairment (p <0.001). Processing speed partially mediated the effect of depression on function and fully mediated the effect of executive dysfunction on function (p <0.001) in the total MCI and aMCI subsample, while in the non-aMCI subsample, processing speed mediated the effect of executive function but not the effect of depression (p = 0.20) on function.

CONCLUSIONS

The findings show that processing speed is central to the effect that depression and executive dysfunction have on functional impairment in cognitively impaired older adults. Future studies are needed to better understand the physiologic underpinnings in age-related and disease-specific decrements in processing speed, and to address the problems in the assessment of processing speed in clinical samples.

Executive dysfunction and treatment response in late-life depression

OBJECTIVES

Executive dysfunction in geriatric depression has been shown to predict poor response to antidepressant medication. The purpose of this review is to clarify which aspects of executive functioning predict poor antidepressant treatment response.

METHODS

Literature review.

RESULTS

From our review, the aspects of executive functioning that appear to be associated with antidepressant response rates are verbal fluency and response inhibition. There is some indication that the semantic strategy component may account for the effects of verbal fluency, although evidence comes from one study and needs replication. Processing speed has been proposed as a substrate that may underlie the effects of executive dysfunction on treatment response. Although processing speed does not appear to account for the relationship between response inhibition and treatment outcome, this issue has yet to be assessed with respect to verbal fluency.

CONCLUSIONS

Verbal fluency and response inhibition are specific aspects of executive dysfunction that appear to impact antidepressant response rates. Disruption of the frontostriatal limbic circuit (particularly the anterior cingulate and dorsolateral prefrontal cortex) may explain the relation between these two mechanisms.

Contribution of spontaneous improvement to placebo response in depression: a meta-analytic review

OBJECTIVES

It is unknown to what degree spontaneous improvement accounts for the large placebo response observed in antidepressant trials for Major Depressive Disorder (MDD). The purpose of this study was to estimate the spontaneous improvement observed in treatment-seeking individuals with acute MDD by determining the symptom change in depressed patients assigned to wait-list controls in psychotherapy studies.

METHOD

The databases PubMed and PsycINFO were searched to identify randomized, prospective studies randomizing outpatients to psychotherapy or a wait-list control condition for the treatment of acute MDD. Standardized effect sizes calculated from each identified study were aggregated in a meta-analysis to obtain a summary statistic for the change in depression scores during participation in a wait-list control.

RESULTS

Ten trials enrolling 340 participants in wait-list control conditions were identified. The estimated effect size for the change in depression scores during wait-list control was 0.505 (95% CI 0.271-0.739, p < 0.001), representing an average improvement of 4 points on the Hamilton Rating Scale for Depression.

DISCUSSION

Depressed patients acutely experience improvement even without treatment, but spontaneous improvement is unlikely to account for the magnitude of placebo response typically observed in antidepressant trials. These findings must be interpreted in light of the small number wait-list control participants available for analysis as well as certain methodological heterogeneity in the psychotherapy studies analyzed.