The aim of this project was to investigate the cognitive abnormalities in healthy individuals (No Axis I or II disorders) at risk for bipolar disorder (BD) and schizophrenia (SZ)

Participants were 17 BD-R and 15 SZ-R and 23 controls. All participants underwent assessment of IQ, inhibition, verbal fluency, planning and cognitive set shifting. Lack of lifetime Axis I and II disorders was screened using Structured Clinical Interview for DSM-IV and symptomatology was assessed with the Brief Psychiatric Rating Scale (BPRS).

No difference was found in IQ. Loss of inhibition was found in both SZ-R and BD-R compared to controls whereas SZ-R had slower initiation times. SZ-R also failed to inhibit relatively fast erroneous responses, leading to an effect on error rates but not in reaction times. SZ-R and BD-R produced fewer words compared to controls whereas the former group made more errors. BD-R achieved both comparable number of categories to controls and made equal number of errors whereas SZ-R underperformed compared to former groups in both measures. Effect of BPRS total score was found only for BD-R across all measures apart from inhibition.

Genetic predisposition to SZ may be mediated by deficits in both the Ventral and Dorsal Prefrontal Cortex (VPFC) and (DPFC). In BD-R impairment was limited in the VPFC whereas the DPFC function was preserved. The two disorders share inhibition deficits associated with the VPFC.