A comparison of cognitive functioning in acute schizophrenia and depression

Neurocognitive deficits in depression: a systematic review of cognitive impairment in the acute and remitted state

Previous research suggests a broad range of deficits in major depressive disorder. Our goal was to update the current assumptions and investigate the extent of cognitive impairment in depression in the acute and remitted state. A systematic review of the existing literature between 2009 and 2019 assessing the risk of bias within the included studies was performed. Of the 42 articles reviewed, an unclear risk of bias was shown overall. The risk of bias mainly concerned the sample selection, inadequate remedial measures, as well as the lack of blinding the assessors. In the acute phase, we found strong support for impairment in processing speed, learning, and memory. Follow-up studies and direct comparisons revealed less pronounced deficits in remission, however, deficits were still present in attention, learning and memory, and working memory. A positive correlation between the number of episodes and cognitive deficits as well as depression severity and cognitive deficits was reported. The results also demonstrate a resemblance between the cognitive profiles in bipolar disorder and depression. Comparisons of depression with schizophrenia led to unclear results, at times suggesting an overlap in cognitive performance. The main findings support the global deficit hypothesis and align with results from prior meta-analyses and reviews. Recommendations for future research are also presented.

Decision Making under Risk in Patients Suffering from Schizophrenia or Depression

Studies have reported difficulties in decision making for patients with schizophrenia or depression. Here, we investigated whether there are differences between schizophrenia patients, depressed patients, and healthy individuals (HC) when decisions are to be made under risk and cognitive flexibility is required. We were also interested in the relationships between decision making, cognitive functioning, and disease severity. Thirty HC, 28 schizophrenia patients, and 28 depressed patients underwent structured clinical assessments and were assessed by the Positive and Negative Syndrome Scale or Hamilton Rating Scale. They performed the Probability-Associated Gambling (PAG) Task and a neuropsychological test battery. Both patient groups obtained lower scores than HC in memory and executive function measures. In the PAG task, relative to HC, depressed patients made slower decisions but showed a comparable number of advantageous decisions or strategy flexibility. Schizophrenia patients were slower, riskier, and less flexible compared to HC. For them, the decision making behavior correlated with the symptom severity. In both groups, decision making scores correlated with memory and executive function scores. Patients with schizophrenia or depression may have difficulties under risk when quick and flexible decisions are required. These difficulties may be more pronounced in patients who have marked cognitive deficits or severe clinical symptoms.

Early childhood depression, emotion regulation, episodic memory, and hippocampal development

Depression in adults is associated with deficits in a number of cognitive domains, however it remains less clear how early in development theses deficits can be detected in early onset depression. There are several different hypotheses about the links between cognitive function and depression. For example, it has been argued that executive function deficits contribute to emotion regulation difficulties, which in turn increase risk for depression. Further, it has been suggested that some cognitive deficits, such as episodic memory, may reflect hippocampal abnormalities linked to both depression and episodic memory. We examined these questions in adolescents participating in a longitudinal study of preschool onset depression. We measured cognitive function at adolescence using the National Institutes of Health toolbox (vocabulary, processing speed, executive function, working memory and episodic memory), and examined relationships of cognitive deficits to depression, emotion regulation, life stress and adversity, as well as hippocampal volume trajectories over three imaging assessments starting at school age. Depression related deficits in episodic memory were found. Youths with either current and past depression showed episodic memory deficits even after controlling for other psychopathology and family income. Depression severity, emotion dysregulation, and life stress/adversity all predicted episodic memory impairment, as did smaller intercepts and slopes of hippocampal growth over time. Modest relationships of depression to hippocampal volume and strong relationships between emotion regulation and both episodic memory and hippocampal volume were found. These data are consistent with prior work in adults linking depression, episodic memory, emotion regulation, life stress/adversity, and hippocampal volume in adults and suggest similar relations are evident as early as adolescence when memory systems are under development. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Phenotypic and genetic analysis of cognitive performance in Major Depressive Disorder in the Generation Scotland: Scottish Family Health Study

Lower performances in cognitive ability in individuals with Major Depressive Disorder (MDD) have been observed on multiple occasions. Understanding cognitive performance in MDD could provide a wider insight in the aetiology of MDD as a whole. Using a large, well characterised cohort (N = 7012), we tested for: differences in cognitive performance by MDD status and a gene (single SNP or polygenic score) by MDD interaction effect on cognitive performance. Linear regression was used to assess the association between cognitive performance and MDD status in a case-control, single-episode-recurrent MDD and control-recurrent MDD study design. Test scores on verbal declarative memory, executive functioning, vocabulary, and processing speed were examined. Cognitive performance measures showing a significant difference between groups were subsequently analysed for genetic associations. Those with recurrent MDD have lower processing speed versus controls and single-episode MDD (β = -2.44, p = 3.6 × 10^-04; β = -2.86, p = 1.8 × 10^-03, respectively). There were significantly higher vocabulary scores in MDD cases versus controls (β = 0.79, p = 2.0 × 10^-06), and for recurrent MDD versus controls (β = 0.95, p = 5.8 × 10^-05). Observed differences could not be linked to significant single-locus associations. Polygenic scores created from a processing speed meta-analysis GWAS explained 1% of variation in processing speed performance in the single-episode versus recurrent MDD study (p = 1.7 × 10^-03) and 0.5% of variation in the control versus recurrent MDD study (p = 1.6 × 10^-10). Individuals with recurrent MDD showed lower processing speed and executive function while showing higher vocabulary performance. Within MDD, persons with recurrent episodes show lower processing speed and executive function scores relative to individuals experiencing a single episode.

Cognitive impairment in schizophrenia and depression: A comparison of stability and course

Cognitive deficits are clinically relevant features in schizophrenia and depression, yet little comparative data on changes in both disorders is available. This study compares cognitive performance of inpatients with schizophrenia (N = 52) and unipolar major depression (N = 67) during psychiatric treatment, assessing performance twice: after admission to hospital (acute) and prior to discharge (postacute) on average seven weeks later. A group of healthy controls was tested at comparable intervals. Data was analyzed using a multivariate linear model. Patients with schizophrenia and depression showed significantly impaired performance compared to healthy controls. On follow-up both patient groups showed improved performance. Contrary to expectation, patients with schizophrenia showed greater improvement in verbal memory, visual memory, and psychomotor speed than depressive patients. Verbal fluency presented as a possible candidate to differentiate between both disorders. Similar profiles of generalized cognitive deficits were observed in both patient-groups on acute and postacute assessment, which might indicate trait-like deficits with persistent functional implications in both disorders. Findings do not support assumptions of greater cognitive impairment in schizophrenia compared to depression. A distinction of the disorders on the grounds of cognitive functioning seems to be less specific than presumed.

Cognitive enhancing effects of rTMS administered to the prefrontal cortex in patients with depression: A systematic review and meta-analysis of individual task effects

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is an approved therapeutic treatment of major depressive disorder and has increasing clinical use throughout the world. However, it remains unclear whether an rTMS course for depression may also produce cognitive enhancement. In a recent meta-analysis of sham-controlled randomized controlled studies (RCTs) conducted in patients with neuropsychiatric conditions, no evidence was found for generalized cognitive enhancing effects across cognitive domains with active compared to sham rTMS. Notwithstanding, there remains the possibility of cognitive effects following an rTMS course that are more highly specific, for example, in specific clinical conditions, or at the individual task level. This study aimed to determine whether a therapeutic rTMS course in patients with depression is associated with cognitive enhancing effects at the task level.

METHODS

A systematic review and meta-analysis of outcomes on individual neuropsychological tasks from sham-controlled RCTs where an rTMS course was administered to the dorsolateral prefrontal cortex (DLPFC) in patients with depression.

RESULTS

Eighteen studies met the inclusion criteria. Active rTMS treatment showed no specific enhancing effects on the majority of cognitive tasks. Modest effect size improvements with active compared to sham rTMS treatment were found for performance on the Trail Making Test Parts A (g = 0.28, 95% CI = 0.06-0.50) and B (g = 0.26, 95% CI = 0.06-0.47).

CONCLUSION

A therapeutic rTMS course administered to the prefrontal cortex for depression may produce modest cognitive enhancing effects specific to psychomotor speed, visual scanning, and set-shifting ability.

Toward Probabilistic Diagnosis and Understanding of Depression Based on Functional MRI Data Analysis with Logistic Group LASSO

Diagnosis of psychiatric disorders based on brain imaging data is highly desirable in clinical applications. However, a common problem in applying machine learning algorithms is that the number of imaging data dimensions often greatly exceeds the number of available training samples. Furthermore, interpretability of the learned classifier with respect to brain function and anatomy is an important, but non-trivial issue. We propose the use of logistic regression with a least absolute shrinkage and selection operator (LASSO) to capture the most critical input features. In particular, we consider application of group LASSO to select brain areas relevant to diagnosis. An additional advantage of LASSO is its probabilistic output, which allows evaluation of diagnosis certainty. To verify our approach, we obtained semantic and phonological verbal fluency fMRI data from 31 depression patients and 31 control subjects, and compared the performances of group LASSO (gLASSO), and sparse group LASSO (sgLASSO) to those of standard LASSO (sLASSO), Support Vector Machine (SVM), and Random Forest. Over 90% classification accuracy was achieved with gLASSO, sgLASSO, as well as SVM; however, in contrast to SVM, LASSO approaches allow for identification of the most discriminative weights and estimation of prediction reliability. Semantic task data revealed contributions to the classification from left precuneus, left precentral gyrus, left inferior frontal cortex (pars triangularis), and left cerebellum (c rus1). Weights for the phonological task indicated contributions from left inferior frontal operculum, left post central gyrus, left insula, left middle frontal cortex, bilateral middle temporal cortices, bilateral precuneus, left inferior frontal cortex (pars triangularis), and left precentral gyrus. The distribution of normalized odds ratios further showed, that predictions with absolute odds ratios higher than 0.2 could be regarded as certain.