Speed of Response to Visual Stimuli May Be Biomarker for Psychosis

Individuals at high risk of psychosis who later develop a full-blown psychotic illness respond more slowly on a test of response time than high-risk individuals who do not, according to areport published today in AJP in Advance. The differences in response time correlated to noticeable differences in the brain ’s electrical activity.Yongqing Hou, Ph.D., of Southwest University in Chongqing, China, and colleagues used electroencephalography (EEG) to measure brain activity of 223 participants during a computerized test in which they were shown square targets with different colors. The task required participants to press the space bar quickly and accurately only when they saw a red square, which appeared 15% of the time. During the rest of the time, they were shown an “interference” square, which was usually blue, but occasionally other colors.The participants (who were all freshmen at Chinese universities) included 122 individuals with psychosis risk syndrome, 50 individuals with an emotional disorder (depression and/or generalized anxiety) but no psychosis risk syndrome, and 51 control subjects with no psychiatric illness. Individuals meeting criteria for psychosis risk were followed for 12 months and reclassified into three subgroups: those who converted to full-blown psychosis, those who did not convert but remained symptomatic, and those who experienced remission from symptoms.Average response time on the test was highest for individuals in the psychosis risk group at...
Source: Psychiatr News - Category: Psychiatry Tags: biomarker EEG N2 amplitude psychosis psychosis risk reaction time visual stimulus Source Type: research