Executive Function Profiles in Pediatric Traumatic Brain Injury.

Traumatic brain injury (TBI) results in heterogeneous patterns of neuropsychological impairment. This study investigated heterogeneity in executive function (EF) using the Comprehensive Trail Making Test (CTMT) to evaluate 121 children and adolescents with TBI and 121 matched normal controls. The TBI group performed approximately two standard deviations below controls. Cluster analyses indicated that a three-cluster solution best classified the TBI group and a four-cluster solution best classified controls. Greater impairment in EF was associated with lower intellectual, achievement, and neuropsychological test performance in the TBI group. Results suggest that EF deficits reflected in CTMT performance may be useful for classifying severity of TBI.

Negative symptoms in bipolar disorder and schizophrenia: A psychometric evaluation of the brief negative symptom scale across diagnostic categories.

Past studies have demonstrated that the Brief Negative Symptom Scale (BNSS) has excellent psychometric properties in patients with schizophrenia. In the current study, we extended this literature by examining psychometric properties of the BNSS in outpatients diagnosed with bipolar disorder (n=46), outpatients with schizophrenia (n=50), and healthy controls (n=27). Participants completed neuropsychological testing and a clinical interview designed to assess negative, positive, disorganized, mood, and general psychiatric symptoms. Results indicated differences among the 3 groups in the severity of all BNSS items, with SZ and BD scoring higher than CN; however, SZ and BD only differed on blunted affect and alogia items, not anhedonia, avolition, or asociality. BD patients with a history of psychosis did not differ from those without a history of psychosis on negative symptom severity. The BNSS had excellent internal consistency in SZ, BD, and CN groups. Good convergent and discriminant validity was apparent in SZ and BD groups, as indicated by relationships between the BNSS and other clinical rating scales. These findings support the validity of the BNSS in broadly defined serious mental illness populations.

Concurrent sound segregation impairments in schizophrenia: The contribution of auditory-specific and general cognitive factors.

The present study sought to test whether perceptual segregation of concurrently played sounds is impaired in schizophrenia (SZ), whether impairment in sound segregation predicts difficulties with a real-world speech-in-noise task, and whether auditory-specific or general cognitive processing accounts for sound segregation problems. Participants with SZ and healthy controls (HCs) performed a mistuned harmonic segregation task during recording of event-related potentials (ERPs). Participants also performed a brief speech-in-noise task. Participants with SZ showed deficits in the mistuned harmonic task and the speech-in-noise task, compared to HCs. No deficit in SZ was found in the ERP component related to mistuned harmonic segregation at around 150ms (the object-related negativity or ORN), but instead showed a deficit in processing at around 400ms (the P4 response). However, regression analyses showed that indexes of education level and general cognitive function were the best predictors of sound segregation difficulties, suggesting non-auditory specific causes of concurrent sound segregation problems in SZ.

Predicting psychosis across diagnostic boundaries: Behavioral and computational modeling evidence for impaired reinforcement learning in schizophrenia and bipolar disorder with a history of psychosis.

There is increasing evidence that schizophrenia (SZ) and bipolar disorder (BD) share a number of cognitive, neurobiological, and genetic markers. Shared features may be most prevalent among SZ and BD with a history of psychosis. This study extended this literature by examining reinforcement learning (RL) performance in individuals with SZ (n = 29), BD with a history of psychosis (BD+; n = 24), BD without a history of psychosis (BD-; n = 23), and healthy controls (HC; n = 24). RL was assessed through a probabilistic stimulus selection task with acquisition and test phases. Computational modeling evaluated competing accounts of the data. Each participant's trial-by-trial decision-making behavior was fit to 3 computational models of RL: (a) a standard actor-critic model simulating pure basal ganglia-dependent learning, (b) a pure Q-learning model simulating action selection as a function of learned expected reward value, and (c) a hybrid model where an actor-critic is "augmented" by a Q-learning component, meant to capture the top-down influence of orbitofrontal cortex value representations on the striatum. The SZ group demonstrated greater reinforcement learning impairments at acquisition and test phases than the BD+, BD-, and HC groups. The BD+ and BD- groups displayed comparable performance at acquisition and test phases. Collapsing across diagnostic categories, greater severity of current psychosis was associated with poorer acquisition of the most rewarding stimuli as well as poor go/no-go learning at test. Model fits revealed that reinforcement learning in SZ was best characterized by a pure actor-critic model where learning is driven by prediction error signaling alone. In contrast, BD-, BD+, and HC were best fit by a hybrid model where prediction errors are influenced by top-down expected value representations that guide decision making. These findings suggest that abnormalities in the reward system are more prominent in SZ than BD; however, current psychotic symptoms may be associated with reinforcement learning deficits regardless of a Diagnostic and Statistical Manual of Mental Disorders (5th Edition; American Psychiatric Association, 2013) diagnosis.

Preliminary evidence for reduced auditory lateral suppression in schizophrenia.

BACKGROUND: Well-documented auditory processing deficits such as impaired frequency discrimination and reduced suppression of auditory brain responses in schizophrenia (SZ) may contribute to abnormal auditory functioning in everyday life. Lateral suppression of non-stimulated neurons by stimulated neurons has not been extensively assessed in SZ and likely plays an important role in precise encoding of sounds. Therefore, this study evaluated whether lateral suppression of activity in auditory cortex is impaired in SZ. METHODS: SZ participants and control participants watched a silent movie with subtitles while listening to trials composed of a 0.5s control stimulus (CS), a 3s filtered masking noise (FN), and a 0.5s test stimulus (TS). The CS and TS were identical on each trial and had energy corresponding to the high energy (recurrent suppression) or low energy (lateral suppression) portions of the FN. Event-related potentials were recorded and suppression was measured as the amplitude change between CS and TS. RESULTS: Peak amplitudes of the auditory P2 component (160-260ms) showed reduced lateral but not recurrent suppression in SZ participants. CONCLUSIONS: Reduced lateral suppression in SZ participants may lead to overlap of neuronal populations representing different auditory stimuli. Such imprecise neural representations may contribute to the difficulties SZ participants have in discriminating complex stimuli in everyday life.

Concordance of the Montreal cognitive assessment with standard neuropsychological measures.

INTRODUCTION: The concordance of the Montreal cognitive assessment (MoCA) with more comprehensive neuropsychological measures remains unclear. This study examined the individual MoCA domains with more comprehensive and commonly used neuropsychological measures to determine the degree of overlap. METHODS: Data included individuals seen in an outpatient neurology clinic specializing in neurodegenerative disease who were administered the MoCA and also underwent neuropsychological assessment (n = 471). A principal component analysis with varimax rotation was completed using the MoCA domain scores and comprehensive neuropsychological evaluation measures. RESULTS: Four factors emerged accounting for 55.6% of the variance: (1) visuospatial/executive functioning; (2) memory; (3) attention; and (4) language. The individual MoCA domain scores demonstrated high factor loadings with standard neuropsychological measures purported to measure similar cognitive constructs. DISCUSSION: These findings provide empirical validation for the MoCA domain classifications, lending further support for the use of the MoCA as a cognitive screen that reflects similar constructs as those measured by a comprehensive battery.

Using negative feedback to guide behavior: impairments on the first 4 cards of the Wisconsin Card Sorting Test predict negative symptoms of schizophrenia.

Research has demonstrated that individuals with schizophrenia fail to appropriately use negative feedback to guide learning. These learning deficits are thought to arise from abnormalities in midbrain dopamine activity. Primary and enduring negative symptoms are also associated with abnormal dopamine activity and are expected to produce more severe deficits in learning when they present in individuals with schizophrenia. The current study examines this matter by comparing individuals with deficit syndrome schizophrenia, which is characterized by primary and enduring negative symptoms, to individuals with nondeficit syndrome schizophrenia and to normal controls in their use of positive feedback and negative feedback to guide learning on the first four cards of the WCST. Participants included 67 individuals with schizophrenia (15 deficit; 52 nondeficit syndrome) and 51 healthy controls. Accuracy data from the first 4 cards of the WCST and measures of global test performance were examined. Individuals with schizophrenia were significantly less accurate than controls in their performance on early (pre-shift) WCST trials, and this impairment was significantly greater in patients with deficit than nondeficit schizophrenia. Additionally, accuracy across the first 4 WCST cards significantly predicted the number of categories completed and percentage of perseverative errors across the entire test. These findings suggest that negative symptoms of schizophrenia are associated with difficulty using negative feedback to adaptively guide behavior, and are consistent with the notion that abnormal DA signaling contributes to the higher-order executive functioning impairments seen in schizophrenia with severe negative symptoms.