The common genetic influence over processing speed and white matter microstructure: Evidence from the Old Order Amish and Human Connectome Projects.

Speed with which brain performs information processing influences overall cognition and is dependent on the white matter fibers. To understand genetic influences on processing speed and white matter FA, we assessed processing speed and diffusion imaging fractional anisotropy (FA) in related individuals from two populations. Discovery analyses were performed in 146 individuals from large Old Order Amish (OOA) families and findings were replicated in 485 twins and siblings of the Human Connectome Project (HCP). The heritability of processing speed was h(2)=43% and 49% (both p<0.005), while the heritability of whole brain FA was h(2)=87% and 88% (both p<0.001), in the OOA and HCP, respectively. Whole brain FA was significantly correlated with processing speed in the two cohorts. Quantitative genetic analysis demonstrated a significant degree to which common genes influenced joint variation in FA and brain processing speed. These estimates suggested common sets of genes influencing variation in both phenotypes, consistent with the idea that common genetic variations contributing to white matter may also support their associated cognitive behavior.

Preventing new episodes of bipolar disorder in adults: Systematic review and meta-analysis of randomized controlled trials.

Uncertainty remains regarding the relative efficacy of maintenance pharmacotherapy for bipolar disorder (BD), and available data require updating. The present systematic review and meta-analysis aims to consolidate the evidence from the highest quality randomized controlled trials (RCTs) published up to July 2021, overcoming the limitations of earlier reviews. The PubMed and the Cochrane Central Register of Controlled Trials were searched for double-blind RCTs involving lithium, mood stabilizing anticonvulsants (MSAs), antipsychotics, antidepressants, and other treatments. Rates of new mood episodes with test vs. reference treatments (placebo or alternative active agent) were compared by random-effects meta-analysis. Polarity index was calculated for each treatment type. Eligible trials involved ≥6 months of maintenance follow up. Of 2,158 identified reports, 22 met study eligibility criteria, and involved 7,773 subjects stabilized for 1-12 weeks and followed-up for 24-104 weeks. Psychotropic monotherapy overall (including lithium, MSAs, and second generation antipsychotics (SGA) was more effective in preventing new BD episodes than placebo (odds ratio, OR=0.42; 95% confidence interval, CI 0.34-0.51, p<0.00001). Significantly lower risk of new BD episodes was observed with the following individual drugs: aripiprazole, asenapine, lithium, olanzapine, quetiapine, and risperidone long-acting (ORs varied 0.19-0.46). Adding aripiprazole, divalproex, quetiapine, or olanzapine/risperidone to lithium or an MSA was more effective compared with lithium or MSA monotherapy (OR=0.37; 95%CI 0.25-0.55, p<0.00001). Active treatment favored prevention of mania over depression. The key limitations were "responder-enriched" design in most trials and high outcomes heterogeneity. PROSPERO registration number is CRD42020162663.

A working memory related mechanism of auditory hallucinations.

Cognitive mechanisms underlying auditory hallucinations (AH) in schizophrenia have been related to working memory (WM), although the formative mechanism is unknown. The phonological loop refers to subvocal rehearsals of information held online for supporting WM. As WM deficiency is frequent in schizophrenia, we hypothesized that AH and WM deficit share a common dysfunction in phonological loop operation, especially when it is taxed by ambiguous auditory and verbal associations. We developed an active phonological priming (APP) paradigm in which participants generated arbitrary verbal associations to pseudowords with ambiguous meaning. They were later asked to rate their familiarity to each pseudoword, a task that required subvocal evaluation of ambiguous auditory-verbal information. Factor and mediation analyses were used to test the hypothesis that WM, AH, and APP induced phonological bias toward perceiving ambiguous contents as familiar may share a common underlying mechanism. In 32 patients with schizophrenia (SZ) and 20 healthy controls (HC), SZ rated ambiguous pseudowords as significantly more familiar compared with HC (p = .006), indicating a proneness to APP-induced bias. This increased subjective bias to perceive ambiguous contents as familiar after APP significantly correlated with AH severity (p = .001) and mediated the relationship between WM and AH. Factor analysis demonstrated a common latent factor among WM, AH, and the bias induced by active priming to ambiguous contents. A heightened phonological loop priming to ambiguous contents appears to be mechanistically linked to WM deficits and AH in schizophrenia. These findings emphasize the importance of jointly addressing WM deficits and AH in clinical practice and research. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Glutamatergic Response to Heat Pain Stress in Schizophrenia.

Regulation of stress response involves top-down mechanisms of the frontal-limbic glutamatergic system. As schizophrenia is associated with glutamatergic abnormalities, we hypothesized that schizophrenia patients may have abnormal glutamatergic reactivity within the dorsal anterior cingulate cortex (dACC), a key region involved in perception of and reaction to stress. To test this, we developed a somatic stress paradigm involving pseudorandom application of safe but painfully hot stimuli to the forearm of participants while they were undergoing serial proton magnetic resonance spectroscopy to measure changes in glutamate and glutamine levels in the dACC. This paradigm was tested in a sample of 21 healthy controls and 23 patients with schizophrenia. Across groups, glutamate levels significantly decreased following exposure to thermal pain, while ratio of glutamine to glutamate significantly increased. However, schizophrenia patients exhibited an initial increase in glutamate levels during challenge that was significantly different from controls, after controlling for heat pain tolerance. Furthermore, in patients, the acute glutamate response was positively correlated with childhood trauma (r = .41, P = .050) and inversely correlated with working memory (r = -.49, P = .023). These results provide preliminary evidence for abnormal glutamatergic response to stress in schizophrenia patients, which may point toward novel approaches to understanding how stress contributes to the illness.

Cognitive profiles and heritability estimates in the Old Order Amish.

OBJECTIVE: This study aimed to establish the applicability of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) in the Old Order Amish (OOA) and to assess the genetic contribution toward the RBANS total score and its cognitive domains using a large family-based sample of OOA. PARTICIPANTS AND METHODS: RBANS data were collected in 103 OOA individuals from Lancaster County, Pennsylvania, including 85 individuals without psychiatric illness and 18 individuals with current psychiatric diagnoses. RESULTS: The RBANS total score and all five cognitive domains of in nonpsychiatric OOA were within half a SD of the normative data of the general population. The RBANS total score was highly heritable (h=0.51, P=0.019). OOA with psychiatric diagnoses had a numerically lower RBANS total score and domain scores compared with the nonpsychiatric participants. CONCLUSION: The RBANS appears to be a suitable cognitive battery for the OOA population as measurements obtained from the OOA are comparable with normative data in the US population. The heritability estimated from the OOA is in line with heritabilities of other cognitive batteries estimated in other populations. These results support the use of RBANS in cognitive assessment, clinical care, and behavioral genetic studies of neuropsychological functioning in this population.