Mismatch negativity and cognitive performance for the prediction of psychosis in subjects with at-risk mental state.
BACKGROUND
A shorter duration of untreated psychosis has been associated with better prognosis in schizophrenia. In this study, we measured the duration mismatch negativity (dMMN), an event-related potential, and cognitive performance in subjects with at-risk mental state (ARMS), patients with first-episode or chronic schizophrenia, and healthy volunteers. The main interest was to determine if these neurocognitive measures predict progression to overt schizophrenia in ARMS subjects.


RESULTS
Seventeen ARMS subjects, meeting the criteria of the Comprehensive Assessment of At-Risk Mental State, 31 schizophrenia patients (20 first-episode and 11 chronic) and healthy controls (N=20) participated in the study. dMMN was measured by an auditory odd-ball paradigm at baseline. Neuropsychological performance was evaluated by the Japanese version of the Brief assessment of cognitive function of schizophrenia (BACS-J). The first-episode schizophrenia group showed significantly smaller amplitudes at frontal electrodes than did control subjects whereas chronic patients elicited smaller amplitudes at frontal and central electrodes, consistent with previous reports. During the follow-up period, 4 out of the 17 ARMS subjects transitioned to schizophrenia (converters) while 13 did not (non-converters). Specifically, dMMN amplitudes of non-converters did not differ from those of healthy controls, while converters showed significantly smaller dMMN amplitudes at some electrodes compared to control subjects. Converters performed significantly worse on tests of working memory, verbal fluency, and attention/information processing than did non-converters. There was a significant positive correlation between dMMN amplitudes at the frontal electrodes and verbal fluency, as measured by the BACS, in the AMRS subjects as a whole.


CONCLUSIONS
ARMS subjects who later developed schizophrenia elicited smaller dMMN amplitudes to begin with, compared to non-converters. Notably, we have provided the first evidence for the ability of verbal fluency to predict dMMN amplitudes in ARMS subjects. These findings are expected to add to the efforts for early diagnosis and intervention of schizophrenia.
Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Science, Toyama, Japan.
Yuko
Y
Higuchi
Tomiki
T
Sumiyoshi
Tomonori
T
Seo
Tomohiro
T
Miyanishi
Yasuhiro
Y
Kawasaki
Michio
M
Suzuki
D000293:Adolescent; D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use; D000068180:Aripiprazole; D003072:Cognition Disorders / Q000188:drug therapy / Q000503:physiopathology* / Q000523:psychology; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010879:Piperazines / Q000627:therapeutic use; D011618:Psychotic Disorders / Q000188:drug therapy / Q000503:physiopathology* / Q000523:psychology; D015363:Quinolones / Q000627:therapeutic use; D012307:Risk Factors; D018967:Risperidone / Q000627:therapeutic use; D012559:Schizophrenia / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D013469:Sulpiride / Q000627:therapeutic use; D055815:Young Adult
D014150:Antipsychotic Agents; D010879:Piperazines; D015363:Quinolones; D013469:Sulpiride; D000068180:Aripiprazole; D018967:Risperidone