Contributions of age and clinical depression to metacognitive performance.

One aspect of metacognition is the ability to judge the accuracy of our own performance, even in the absence of external feedback, which is often measured using confidence ratings. Past research suggests that confidence is lower in Major Depressive Disorder (MDD). Less is known about the ability of MDD patients to discriminate correct from incorrect performance (metacognitive efficiency). The metacognitive performance of aged MDD patients (62-89y) was compared to an age-matched control group. A younger control group (21-28y) was included to also explore the relationshipbetweenageandmetacognitive performance. We found no difference in confidence bias nor metacognitive efficiency between MDD patients and age-matched controls.We found age-related differences in metacognition:normal aging was associated with higher confidencebut lower metacognitive efficiency. The overconfidence was specifically driven by overconfidence in incorrect trials. Our results point to the importance ofage while investigating the relation between MDD and metacognitive performance.

Profiling of the Peripheral Blood Mononuclear Cell Proteome in Schizophrenia and Mood Disorders for the Discovery of Discriminatory Biomarkers: A Proof-of-Concept Study.

INTRODUCTION: Current diagnoses in psychiatry are solely based on the evaluation of clinical presentation by the treating psychiatrist. This results in a high percentage of misdiagnosis and consequential inefficient treatment; especially regarding major depressive disorder (MDD), depression in the context of bipolar disorder (BD-D), bipolar disorder with manic symptoms (BD-M), and psychosis in the context of schizophrenia (SZ). Objective biomarkers allowing for accurate discriminatory diagnostics are therefore urgently needed. METHODS: Peripheral blood mononuclear cell (PBMC) proteomes of patients with MDD (n = 5) , BD-D (n = 3), BD-M (n = 4), and SZ (n = 4), and also of healthy controls (HC; n = 6) were analyzed by state-of-the-art mass spectrometry. Proteins with a differential expression of a >2 standard deviation (SD) expression fold change from that of the HC and between either MDD versus BD-D or BD-M versus SZ were subsequently identified as potential discriminatory biomarkers. RESULTS: In total, 4,271 individual proteins were retrieved from the HC. Of these, about 2,800 were detected in all patient and HC samples. For objective discrimination between MDD and BD-D, 66 candidate biomarkers were found. In parallel, 72 proteins might harbor a biomarker capacity for differential diagnostics of BD-M and SZ. A single biomarker was contraregulated versus HC in each pair of comparisons. DISCUSSION: With this work, we provide a register of candidate biomarkers with the potential to objectively discriminate MDD from BD-D, and BD-M from SZ. Although concerning a proof-of-concept study with limited sample size, these data provide a stepping-stone for follow-up research on the validation of the true discriminatory potential and feasibility of clinical implementation of the discovered biomarker candidates.

Cognitive Deficits in Older Adults With Psychotic Depression: A Meta-Analysis.

A major depressive disorder with psychotic features, that is, psychotic depression (PD), is often accompanied by cognitive deficits, particularly in older patients. We aimed to assess to what extent various cognitive domains are affected in older patients with PD compared to those with nonpsychotic depression (NPD). Therefore, a systematic search was conducted in Medline, Embase, Web of Science, the Cumulative Index to Nursing and Allied Literature (CINAHL), Google Scholar, and Cochrane for all relevant studies. Hereafter, we conducted a meta-analysis of seven studies on cognitive deficits in older adults (55+ years), comparing patients with PD and patients with NPD. Compared to patients with NPD, those with PD not only showed a significantly poorer performance on overall cognitive function, with a Hedges' g effect size of -0.34 (95% confidence interval: -0.56; -0.12; p = 0.003), but also on nearly all separate cognitive domains, with Hedges' g effect sizes ranging from -0.26 to -0.64 (all p's <0.003), of which attention was most adversely affected. Verbal fluency showed no significant effect, although this analysis may have been underpowered. The funnel plot suggested no significant publication bias (Egger test intercept: -2.47; 95% confidence interval: -5.50; 0.55; p = 0.09). We conclude that older patients with PD show more cognitive deficits on all cognitive domains, except for verbal fluency, compared to patients with NPD. It is crucial that clinicians and researchers take cognitive deficits into consideration in older adults with PD.