Increased saccadic rate during smooth pursuit eye movements in patients at Ultra High Risk for developing a psychosis

Abnormalities in eye tracking are consistently observed in schizophrenia patients and their relatives and have been proposed as an endophenotype of the disease. The aim of this study was to investigate the performance of patients at Ultra High Risk (UHR) for developing psychosis on a task of smooth pursuit eye movement (SPEM). Forty-six UHR patients and twenty-eight age and education matched controls were assessed with a task of SPEM and psychiatric questionnaires. Our results showed that both the corrective and non-corrective saccadic rates during pursuit were higher in the UHR group. There were however no differences in smooth pursuit gain between the two groups. The saccadic rate was related to positive UHR symptoms. Our findings indicate that abnormalities in SPEM are already present in UHR patients, prior to a first psychotic episode. These abnormalities occur only in the saccadic system.

P300 deficits are present in young first-episode patients with schizophrenia and not in their healthy young siblings

OBJECTIVE

To evaluated P300 (P3b) abnormalities in young first episode patients with schizophrenia and their healthy young siblings.

METHODS

An auditory oddball paradigm was used to assess P300 in 53 patients, 27 unaffected siblings and 28 healthy controls. Amplitude and latency of the three midline sites (Fz, Cz, and Pz) were compared between patients, siblings, and controls by a mixed-effects regression model.

RESULTS

P300 amplitude was significantly reduced in patients with schizophrenia but not in healthy siblings, when compared to healthy controls. P300 latency did not significantly differ between the three groups.

CONCLUSIONS

P300 amplitude but not latency was found to be affected in young patients with recent onset schizophrenia. However, P300 amplitude and latency were found not to be affected in healthy unaffected young siblings and, therefore, did not qualify as an endophenotype for schizophrenia.

SIGNIFICANCE

The failure to find the P300 (P3b) abnormality in healthy siblings of patients with schizophrenia is an important finding and should be added to P300 literature.

Antisaccade deficit is present in young first-episode patients with schizophrenia but not in their healthy young siblings

BACKGROUND

Results of studies on antisaccade (AS) deficit in relatives of patients with schizophrenia are inconclusive. We hypothesized that AS performance in siblings of patients with schizophrenia is worse than in healthy controls and better than in patients with schizophrenia.

METHOD

We included 55 first-episode patients with schizophrenia, 28 healthy siblings and 36 healthy controls to evaluate AS performance. Eye movements were measured electromagnetically by the double magnetic induction (DMI) method.

RESULTS

Patients with schizophrenia had a significantly higher error rate than siblings (d=0.86, p<0.0001) and controls (d=1.35, p<0.0001). Siblings had a higher mean error rate than healthy controls but this did not reach significance (d=0.56, p=0.29). The intra-class correlation (ICC) was 0.33 for the error rate. Mean AS gain was higher in siblings than in patients (d=0.75, p=0.004) and controls (d=0.6, p=0.05). The ICC was 0.08.

CONCLUSION

As parameters in strictly screened healthy young siblings of young first-episode patients with schizophrenia are comparable to results found in studies investigating older relatives. However, the statistical results (i.e. the ICCs) suggest that there is little evidence of shared environmental or genetic factors on error rate variation.