The prevalence of visual hallucinations in non-affective psychosis, and the role of perception and attention.

BACKGROUND: Little is known about visual hallucinations (VH) in psychosis. We investigated the prevalence and the role of bottom-up and top-down processing in VH. The prevailing view is that VH are probably related to altered top-down processing, rather than to distorted bottom-up processing. Conversely, VH in Parkinson's disease are associated with impaired visual perception and attention, as proposed by the Perception and Attention Deficit (PAD) model. Auditory hallucinations (AH) in psychosis, however, are thought to be related to increased attention. METHOD: Our retrospective database study included 1119 patients with non-affective psychosis and 586 controls. The Community Assessment of Psychic Experiences established the VH rate. Scores on visual perception tests [Degraded Facial Affect Recognition (DFAR), Benton Facial Recognition Task] and attention tests [Response Set-shifting Task, Continuous Performance Test-HQ (CPT-HQ)] were compared between 75 VH patients, 706 non-VH patients and 485 non-VH controls. RESULTS: The lifetime VH rate was 37%. The patient groups performed similarly on cognitive tasks; both groups showed worse perception (DFAR) than controls. Non-VH patients showed worse attention (CPT-HQ) than controls, whereas VH patients did not perform differently. CONCLUSIONS: We did not find significant VH-related impairments in bottom-up processing or direct top-down alterations. However, the results suggest a relatively spared attentional performance in VH patients, whereas face perception and processing speed were equally impaired in both patient groups relative to controls. This would match better with the increased attention hypothesis than with the PAD model. Our finding that VH frequently co-occur with AH may support an increased attention-induced 'hallucination proneness'.

The effects of guided discontinuation of antipsychotics on neurocognition in first onset psychosis.

OBJECTIVE: To assess the effects of second generation antipsychotics on neurocognitive function in patients with stable remission of first episode psychosis. METHODS: Fifty-three patients with first onset psychosis in the schizophrenia spectrum entered a randomised controlled trial of guided discontinuation (GD) versus maintenance treatment (MT) with second generation antipsychotics. A comprehensive neurocognitive test battery was administered at the time of remission and shortly after dose reduction or discontinuation (GD-group) or at the same time in the MT-group. RESULTS: With the exception of negative symptoms, PANSS scores decreased over time and neurocognition improved significantly on most tests in both groups. The GD-group, however, improved significantly more than the MT-group on three neurocognitive measures in the domain of speed of processing. CONCLUSION: These data suggest that, in first episode patients, dose reduction or discontinuation of second generation antipsychotics after stable remission is achieved, might improve neurocognitive function more than continuing second generation antipsychotics, suggesting a negative role for second generation antipsychotics, specifically in the domain of speed of processing.

[Typical and atypical antipsychotics: Is there a difference in their influence on neurocognition?]. / Typische en atypische antipsychotica bij patiënten met schizofrenie: is er verschil in invloed op neurocognitie?

BACKGROUND: Neurocognitive dysfunction is a core feature of schizophrenia and is related to the functional outcome of the illness. It has been suggested that the so-called atypical antipsychotics may have a more favourable influence on neurocognition than the older, typical antipsychotics and thus also on the functional outcome. AIM: To review the recent scientific literature concerning the effects of antipsychotics on neurocognition. METHOD: The literature was reviewed systematically via the most important databases. RESULTS: Meta-analyses suggest that atypical antipsychotics have moderate, positive effects on neurocognition and in that respect are more beneficial than typical antipsychotics. Recent studies, however, challenge this finding. CONCLUSION: The reported positive, cognitive effects of atypical antipsychotics are slight, particularly compared to the severity of neurocognitive dysfunction found in schizophrenia. In clinical practice there seem to be no convincing reason for attaching much weight to any differential effects that typical or atypical antipsychotics may have on neurocognition.

Patients with obsessive-compulsive disorder are impaired in associative learning based on external feedback.

BACKGROUND: Patients with obsessive-compulsive disorder (OCD) have to repeat their actions before feeling satisfied that the action reached its intended goal. Learning theory predicts that this may be due to a failure in the processing of external feedback. METHOD: We examined the performance of 29 OCD patients and 28 healthy volunteers on an associative learning task, in which initial learning is based solely on external feedback signals. Feedback valence was manipulated with monetary gains and losses. RESULTS: As predicted, OCD patients were impaired during initial, external feedback-driven learning but not during later learning stages. The emotional salience of the feedback modulated learning during the initial stage in patients and controls alike. During later learning stages, however, patients approached near-normal performance with rewarding feedback but continued to produce deficient learning with punishing feedback. CONCLUSION: OCD patients have a fundamental impairment in updating behavior based on the external outcome of their actions, possibly mediated by faulty error signals in response selection processes.

Neuroticism, recall bias and attention bias for valenced probes: a twin study.

BACKGROUND: Prior research on the nature of the vulnerability of neuroticism to psychopathology suggests biases in information processing towards emotional rather than neutral information. It is unclear to what extent this relationship can be explained by genetic or environmental factors. METHOD: The genetic relationship between a neuroticism composite score and free recall of pleasant and unpleasant words and the reaction time on negative probes (dot-probe task) was investigated in 125 female twin pairs. Interaction effects were modelled to test whether the correlation between neuroticism and cognitive measures depended on the level of the neuroticism score. RESULTS: The only significant correlation was between neuroticism and the proportion of recalled unpleasant words (heritability is 30%), and was only detectable at the higher end of the neuroticism distribution. This interaction effect seems to be due to environmental effects that make people in the same family more similar (e.g. parental discipline style), rather than genetic factors. An interesting sub-finding was that faster reaction times for left versus right visual field probes in the dot-probe task suggest that cognitive processing in the right hemisphere is more sensitive to subliminal (biologically relevant) cues and that this characteristic is under substantial genetic control (49%). Individual differences in reaction times on right visual field probes were due to environmental effects only. CONCLUSIONS: There is no evidence that the predisposition of individuals to focus on negative (emotional) stimuli is a possible underlying genetic mechanism of neuroticism.

Sustained and transient attention in the continuous performance task.

One of the most frequently applied methods to study abnormal cognition is the Continuous Performance Task (CPT). It is unclear, however, which cognitive functions are engaged in normal CPT performance. The aims of the present study were to identify the neurocognitive functions engaged in the main variants of the CPT and to determine to what extent these variants differentially engage these functions. We hypothesized that the main CPT versions (CPT-X, CPT-AX, CPT-Identical Pairs) can be distinguished by whether they demand sustained or transient attention and sustained or transient response preparation. Transient attention to objects like letters or digits, that is, the need to switch attention to different objects from trial to trial, impairs target detection accuracy relative to sustained attention to a single object. Transient response preparation, that is, the possibility to switch response preparation on and off from trial to trial, improves response speed relative to having to sustain response preparation across all trials. Comparison of task performance and Event-Related brain Potentials (ERPs) of healthy participants obtained in the main CPT variants confirmed these hypotheses. Behavioral and ERP measures indicated worse target detection in the CPT-AX than in the CPT-X, consistent with a higher demand on transient attention in that task. In contrast, behavioral and ERP measures indicated higher response speed in the CPT-AX than in the CPT-X, associated with more response preparation in advance of the targets. This supports the idea of increased transient response preparation in the CPT-AX. We conclude that CPTs differ along at least two task variables that each influences a different cognitive function.

Brain potentials and behavioral responses associated with attention to hard- and easy-to-discriminate passive knee joint movements.

We investigated event-related brain potentials (ERPs) to passive ramp movements of the knee joint. The knee movements were either attended or unattended and were either very easy or very hard to detect. We used special methods to ensure that movement only activated muscle spindle and joint receptors. The first movement-related ERP started 20 ms after movement onset, and had a contralateral maximum. This initial ERP did not differ as a function of attention and movement discriminability. Signal detection analysis of the behavioral data suggested that hard-to-detect movements could be discriminated above chance level, but were not reported because of a decision bias. At 60-100 ms, an ERP was observed that discriminated detected from undetected hard-to-detect movements. Starting at 80 ms, we found an ERP that was unique to movements that were attended and easy to detect. We discuss that (1) the initial ERP reflects activation of preconscious sensory processors, (2) the second ERP may reflect detection that fails to attract attention, and (3) the third ERP reflects active focusing of attention on the movement.