Researchers found no association between slow wave electroencephalography (EEG) power and global functioning in patients at ultra-high risk (UHR) for psychosis, according to a study published in Schizophrenia Research.

Participants were recruited from the Neurapro study, a randomized controlled trial of the role of omega-3 fatty acids in UHR psychosis risk. According to Neurapro protocol, participants underwent full clinical assessment at baseline with the Comprehensive Assessment of At-Risk Mental States to confirm UHR status. EEG recordings were captured at baseline and transition-to-psychosis status was assessed every month during the first 6 months and then again at the 9-, 12-, and 24-month follow-up time points. Of 106 participants (age 15-25 years) with UHR in the original study, 47 agreed to participate in the present analysis. A group of 46 healthy controls was recruited for comparison data. Negative symptoms, depression severity, and clinical global impressions were measured in the UHR group only. Social and global functioning was assessed in both controls and in the UHR group. Patients in the UHR group who later transitioned to psychosis (UHR-P) during the study period were compared with patients who did not transition (UHR-NP) to capture between-group differences in brain wave activity.

Related Articles

The final analysis included data from 44 controls and 38 participants at UHR for psychosis. Study groups did not differ in age or gender distribution. Healthy controls scored significantly higher on all 4 functioning scales than patients in the UHR group. Specifically, controls performed better on the Social and Occupational Functioning Assessment Scale (P =.001), the Global Functioning role and social scales, and the Assessment of Quality of Life – 8 dimensions scale (all P =.000). Although no difference in brain activity power was observed between the UHR group and controls in the delta band (P =.138), power in the theta frequency bands was much greater among patients at UHR for psychosis compared with controls (P =.005).

During the 12-month study period, 8 participants in the UHR group transitioned to psychosis. UHR-NP and UHR-P groups did not differ in age and gender distribution at baseline, although patients in the UHR-P group experienced greater psychiatric symptoms as measured by the Brief Psychiatric Rating Scale (P =.013). Even so, no significant differences were observed between UHR-P and UHR-NP groups in the delta band (P =.086) or the theta band (P =.587). Among all patients in the UHR group, a significant positive correlation was observed between Montgomery-Åsberg Depression Rating Scale scores and frontal delta power (P =.042). No other significant correlations were found between psychiatric symptom scale scores and frontal brain activity in the delta and theta frequency bands in any study group.

These data suggest that while frontal slow wave EEG power may be greater in patients at UHR for psychosis compared with controls, differences do not persist between patients who later transition to psychosis and patients who do not. Additionally, only depressive symptoms were associated with brain wave activity, compared with functioning and negative symptom scale scores.

Researchers noted that the study was limited by a small UHR-P group.

Further research is necessary to capture the time points during the illness course at which brain wave activity becomes impaired.  

Researchers concluded, “Finding the right biomarker to add to the UHR criteria…is imperative in order to minimize the duration of untreated psychosis, maximize therapeutic engagement, and consequently delay or…prevent the onset of psychosis.”

Reference

Sollychin M, Jack BN, Polari A, et al. Frontal slow wave resting EEG power is higher in individuals at Ultra High Risk for psychosis than in healthy controls but is not associated with negative symptoms or functioning [published online February 6, 2019]. Schizophr Res. doi: 10.1016/j.schres.2019.01.039