Delay Discounting as a Transdiagnostic Process in Psychiatric Disorders: A Meta-analysis

Importance Delay discounting is a behavioral economic index of impulsive preferences for smaller-immediate or larger-delayed rewards that is argued to be a transdiagnostic process across health conditions. Studies suggest some psychiatric disorders are associated with differences in discounting compared with controls, but null findings have also been reported. Objective To conduct a meta-analysis of the published literature on delay discounting in people with psychiatric disorders. Data Sources PubMed, MEDLINE, PsycInfo, Embase, and Web of Science databases were searched through December 10, 2018. The psychiatric keywords used were based on DSM-IV or DSM-5 diagnostic categories. Collected data were analyzed from December 10, 2018, through June 1, 2019. Study Selection Following a preregistered Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol, 2 independent raters reviewed titles, abstracts, and full-text articles. English-language articles comparing monetary delay discounting between participants with psychiatric disorders and controls were included. Data Extraction and Synthesis Hedges g effect sizes were computed and random-effects models were used for all analyses. Heterogeneity statistics, one-study-removed analyses, and publication bias indices were also examined. Main Outcomes and Measures Categorical comparisons of delay discounting between a psychiatric group and a control group. Results The sample included 57 effect sizes from 43 studies across 8 diagnostic categories. Significantly steeper discounting for individuals with a psychiatric disorder compared with controls was observed for major depressive disorder (Hedges g = 0.37; P = .002; k = 7), schizophrenia (Hedges g = 0.46; P = .004; k = 12), borderline personality disorder (Hedges g = 0.60; P < .001; k = 8), bipolar disorder (Hedges g = 0.68; P < .001; k = 4), bulimia nervosa (Hedges g = 0.41; P = .001; k = 4), and binge-eating disorder (Hedges g = 0.34; P = .001; k = 7). In contrast, anorexia nervosa exhibited statistically significantly shallower discounting (Hedges g = –0.30; P < .001; k = 10). Modest evidence of publication bias was indicated by a statistically significant Egger test for schizophrenia and at the aggregate level across studies. Conclusions and Relevance Results of this study appear to provide empirical support for delay discounting as a transdiagnostic process across most of the psychiatric disorders examined; the literature search also revealed limited studies in some disorders, notably posttraumatic stress disorder, which is a priority area for research

Latent semantic variables are associated with formal thought disorder and adaptive behavior in older inpatients with schizophrenia

Introduction: Formal thought disorder is a hallmark feature of schizophrenia in which disorganized thoughts manifest as disordered speech. A dysfunctional semantic system and a disruption in executive functioning have been proposed as possible mechanisms for formal thought disorder and verbal fluency impairment. Traditional rating scales and neuropsychological test scores might not be sensitive enough to distinguish among types of semantic impairments. This has lead to the proposed used of a natural language processing technique, Latent Semantic Analysis (LSA), which offers improved semantic sensitivity. Method: In this study, LSA, a computational, vector-based text analysis technique to examine the contribution of vector length, an LSA measure related to word unusualness and cosines between word vectors, an LSA measure of semantic coherence to semantic and phonological fluency, disconnectedness of speech, and adaptive functioning in 165 older inpatients with schizophrenia. Results: In stepwise regressions word unusualness was significantly associated with semantic fluency and phonological fluency, disconnectedness in speech, and impaired functioning, even after considering the contribution of premorbid cognition, positive and negative symptoms, and demographic variables. Conclusions: These findings support the utility of LSA in examining the contribution of coherence to thought disorder and the its relationship with daily functioning. Deficits in verbal fluency may be an expression of underlying disorganization in thought processes

Neurocognition, functional capacity, and functional outcomes: The cost of inexperience

Neurocognitive impairments are the strongest predictor of functional deficits in schizophrenia, but adaptive (i.e., functional) capacity, typically measured with performance-based assessments, yields an objective index of current abilities, whereas real-world functional performance relies on observations of community activity. However, limited experiences in the community may limit the acquisition, retention, or expression of these skills. We examined the frequency of engagement in behaviors that are assessed in the current “gold standard” in person functional capacity assessment. The UCSD Performance-Based Skills Assessment (i.e., UPSA) examines skills associated with recreational engagement, handling money, scheduling appointments, and navigating public transportation. We used neurocognition, experience, and UPSA performance as predictors of the relationships among cognition and real-world functioning variables. Neurocognition was a significant correlate of UPSA scores regardless of whether it was forced into the model before or after prior experience, whereas experience was only a significant predictor of UPSA scores when entered before neurocognition. Further, functional capacity, neurocognition, and experience were significant predictors of real-world outcomes and experience remained a significant predictor regardless of the order it was entered into the model. The amount of current experience with functional tasks is not a rate-limiter of the relationships between neurocognition and functional capacity but does account for some previously unexplained variance in the functional capacity–everyday functioning relationship. These findings underscore the importance of neurocognitive deficits as they relate to functional capacity in schizophrenia, and suggest an incremental functional cost of limited experience with independent living

Working Overtime: Altered Functional Connectivity in Working Memory Following Regular Cannabis Use in Young Adults

There is an emerging consensus that regular cannabis use may be detrimental to the developing brain, including potential long-lasting changes in executive functioning. Consequently, the present study examined neural activation and performance on a working memory n-back task using functional magnetic resonance imaging (fMRI) in a sample of young adults (ages 19 to 21) from a longitudinal research sample. Regular cannabis users (n = 10) were compared with non-regular cannabis user controls (n = 14) while completing the letter n-back task during fMRI. While there were no differences across performance indices, imaging parameters showed significant differences in brain activation during task performance. Specifically, there wa