Computer-Assisted Cognitive Remediation in Schizophrenia: Efficacy of an Individualized vs. Generic Exercise Plan.

Computer-assisted cognitive remediation (CACR) is an economical, adjustable, and effective treatment for individuals with schizophrenia. The current randomized controlled study examined whether an individualized or generic exercise plan in CACR is superior in patients with multiple cognitive deficits compared to treatment-as-usual (TAU). Fifty-nine inpatients diagnosed with schizophrenia were randomly assigned to 1) TAU, 2) TAU plus an individualized exercise plan in CACR, or 3) TAU plus a generic exercise plan in CACR. Neuropsychological performance, psychopathology, and functional outcome were assessed at baseline and post-treatment. The results show a medium to large training effect for all neuropsychological performance measures. Contrary to our expectations the neuropsychological improvement over time did not differ between groups. Self-reported depression, global level of functioning, and activity and participation functioning showed a significant improvement from baseline to post-treatment. However no further group, time, or interaction effects for other psychopathology and functional outcome could be demonstrated. Possible implications for clinical use of CACR and future studies are discussed.

Simulated car driving and its association with cognitive abilities in patients with schizophrenia.

OBJECTIVES: Patients with schizophrenia commonly suffer from impairments in various aspects of cognition. These deficits were shown to have detrimental effects on daily life functioning and might also impair car driving. This study is the first to examine driving behaviour of patients with schizophrenia using an advanced driving simulator, and to explore the role of cognitive abilities of people with schizophrenia for driving. METHODS: Non-acute patients with schizophrenia (n = 31) and healthy comparison participants (n = 31) performed a comprehensive neuropsychological assessment and driving simulator rides. Neuropsychological and driving performances were compared between groups. Moreover, associations were explored between cognitive functions and driving behaviour in the entire group. RESULTS: Patients with schizophrenia revealed impairments in multiple aspects of cognition. In the driving simulator, patients with schizophrenia showed no indication of deviant driving in terms of number of collisions or reacting to critical situations, and even showed better lane control compared to healthy individuals. However, patients with schizophrenia drove significantly slower than healthy individuals, and caused more hindrance to the car behind while merging on the motorway. Slower driving was associated with lower test scores on attention and processing speed. Hindering the car behind was associated with test performance on planning and inhibition. CONCLUSIONS: It is concluded that driving of patients with schizophrenia is characterized by a relatively slow speed, and can also be impaired in certain aspects, i.e. hindering a car behind while merging. Cognitive functions are crucial for driving, and should be target of treatment.

Deficits in reinforcement learning but no link to apathy in patients with schizophrenia.

Negative symptoms in schizophrenia have been linked to selective reinforcement learning deficits in the context of gains combined with intact loss-avoidance learning. Fundamental mechanisms of reinforcement learning and choice are prediction error signaling and the precise representation of reward value for future decisions. It is unclear which of these mechanisms contribute to the impairments in learning from positive outcomes observed in schizophrenia. A recent study suggested that patients with severe apathy symptoms show deficits in the representation of expected value. Considering the fundamental relevance for the understanding of these symptoms, we aimed to assess the stability of these findings across studies. Sixty-four patients with schizophrenia and 19 healthy control participants performed a probabilistic reward learning task. They had to associate stimuli with gain or loss-avoidance. In a transfer phase participants indicated valuation of the previously learned stimuli by choosing among them. Patients demonstrated an overall impairment in learning compared to healthy controls. No effects of apathy symptoms on task indices were observed. However, patients with schizophrenia learned better in the context of loss-avoidance than in the context of gain. Earlier findings were thus partially replicated. Further studies are needed to clarify the mechanistic link between negative symptoms and reinforcement learning.

Intraindividual variability in inhibitory function in adults with ADHD--an ex-Gaussian approach.

OBJECTIVE: Attention deficit disorder (ADHD) is commonly associated with inhibitory dysfunction contributing to typical behavioral symptoms like impulsivity or hyperactivity. However, some studies analyzing intraindividual variability (IIV) of reaction times in children with ADHD (cADHD) question a predominance of inhibitory deficits. IIV is a measure of the stability of information processing and provides evidence that longer reaction times (RT) in inhibitory tasks in cADHD are due to only a few prolonged responses which may indicate deficits in sustained attention rather than inhibitory dysfunction. We wanted to find out, whether a slowing in inhibitory functioning in adults with ADHD (aADHD) is due to isolated slow responses. METHODS: Computing classical RT measures (mean RT, SD), ex-Gaussian parameters of IIV (which allow a better separation of reaction time (mu), variability (sigma) and abnormally slow responses (tau) than classical measures) as well as errors of omission and commission, we examined response inhibition in a well-established GoNogo task in a sample of aADHD subjects without medication and healthy controls matched for age, gender and education. RESULTS: We did not find higher numbers of commission errors in aADHD, while the number of omissions was significantly increased compared with controls. In contrast to increased mean RT, the distributional parameter mu did not document a significant slowing in aADHD. However, subjects with aADHD were characterized by increased IIV throughout the entire RT distribution as indicated by the parameters sigma and tau as well as the SD of reaction time. Moreover, we found a significant correlation between tau and the number of omission errors. CONCLUSIONS: Our findings question a primacy of inhibitory deficits in aADHD and provide evidence for attentional dysfunction. The present findings may have theoretical implications for etiological models of ADHD as well as more practical implications for neuropsychological testing in aADHD.

Complex prospective memory in adults with attention deficit hyperactivity disorder.

OBJECTIVES: Attention deficit hyperactivity disorder (ADHD) in adults has been associated with disturbances of attention and executive functions. Furthermore, impairments of verbal and figural retrospective memory were reported. However, little is known about the effects of ADHD on prospective memory, the execution of delayed intentions in the future. METHODS: The present study compared the performance of 45 adult patients with ADHD not treated with stimulant medication with the performance of 45 matched healthy individuals on a paradigm of complex prospective memory which measured task planning, plan recall, self-initiation and execution. Furthermore, the contribution of other cognitive functions to prospective memory functioning was assessed, including measures of attention, executive functions and memory. RESULTS: A large-scale impairment could be observed in task planning abilities in patients with ADHD. Only negligible to small effects were found for plan recall, self-initiation and execution. Inhibition was identified to contribute significantly to performance on task planning. CONCLUSIONS: The present findings suggest that four cognitive components contribute to the performance of prospective memory. Impairments of prospective memory mainly emerged from deficient planning abilities in adults with ADHD. Implications on behavioral based intervention strategies are discussed.