Nicotine enhances antisaccade performance in schizophrenia patients and healthy controls.

Nicotine has been proposed to be a cognitive enhancer, particularly in schizophrenia patients. So far, the published studies of nicotine effects on antisaccade performance in schizophrenia patients only tested participants who were deprived smokers. Thus, we aimed to test both smoking and non-smoking patients as well as healthy controls in order to extend previous findings. Moreover, we employed a paradigm using standard and delayed trials. We hypothesized that, if nicotine is a genuine cognitive enhancer, its administration would improve antisaccade performance both in smoking and non-smoking participants. A total of 22 patients with schizophrenia (12 smokers and 10 non-smokers) and 26 controls (14 smokers and 12 non-smokers) completed the study. The effects of a nicotine patch (14 mg for smokers, 7 mg for non-smokers) on antisaccade performance were tested in a randomized, double-blind, placebo-controlled, cross-over trial. Schizophrenia patients made significantly more antisaccade errors than controls (p = 0.03). Both patients and controls made fewer antisaccade errors in the delayed trials than in the standard trials (p < 0.0001). Nicotine significantly reduced antisaccade error rate in the standard trials, but not in the delayed trials (p = 0.02). Smoking status did not influence the nicotine effect on antisaccade error rate (p = 0.10) indicating an equal procognitive effect of nicotine in smokers and non-smokers. Overall the present findings indicate that beneficial effects of nicotine on antisaccade performance are not confined to smoking schizophrenia patients. Instead, the findings likely represent genuine nicotine-induced enhancement of cognitive performance.

Temporal dynamics of suspiciousness and hallucinations in clinical high risk and first episode psychosis.

The objective of the current study is to elucidate the temporal dynamics of suspiciousness and hallucinations as they occur in daily life in the early stages of psychosis. Their prevalence and co-occurrence, as well as their temporal relation to affect and delusions, were compared between patients with a first psychotic episode (FEP) and individuals at clinical high risk for psychosis (CHRp). The Experience Sampling Method was used to investigate suspiciousness and hallucinatory experiences, delusions, and affect at semi-random moments throughout six days in 33 CHRp and 34 FEP. Overall, 91% of CHRp and 59% of FEP reported suspiciousness, and 24% and 39% reported hallucinations, respectively. Hallucinations almost always co-occurred with suspiciousness, whereas suspiciousness was often present without hallucinations. Suspicious episodes in CHRp occurred with marked increases in delusional intensity, while hallucinatory experiences were mostly absent. In FEP, a decrease of positive affect preceded suspicious episodes, while an increase of negative affect preceded hallucinatory episodes. Our results indicated the presence of a delusional mood (atmosphere) in CHRp as an experience in itself, without co-occurring or following hallucinations, thus refuting the anomalous experience hypothesis of psychosis. The co-occurrence of hallucinations, on the other hand, indicates a more severe stage of symptomatology.