BACKGROUND: Impaired cortical inhibition is a well-established finding in @entity161 @entity1 and has been linked to dysfunctional @entity1246 ( @entity1246 )ergic transmission. However, there have been no previous studies investigating cortical excitability with particular regard to intracortical inhibitory networks in antipsychotic-naive subjects at risk of developing first-episode @entity716 . METHODS: A total of 18 subjects at risk, 18 first-episode @entity161 @entity1 , and 18 healthy control subjects were included in this study. Transcranial magnetic stimulation over the left primary motor cortex was used to determine short-latency intracortical inhibition, intracortical facilitation, and the contralateral silent period (CSP). Short-latency intracortical inhibition can be considered as a parameter of @entity1246 type A ( @entity1246 (A))-mediated inhibition and it has been proposed that CSP can test @entity1246 type B ( @entity1246 (B))-mediated inhibitory intracortical networks. RESULTS: Subjects at risk and first-episode @entity1 showed a reduced short-latency intracortical inhibition compared with healthy control subjects, suggesting reduced @entity1246 (A)-mediated inhibition. First-episode @entity1 had a prolonged CSP duration compared with the other two groups, implying a @entity1246 (B) imbalance only in @entity1 with full-blown @entity716 . Analyses did not reveal group differences for intracortical facilitation. CONCLUSIONS: These results indicate specific alterations in inhibitory cortical networks in subjects at risk and in first-episode @entity1 . It appears that there is already a cortical inhibitory deficit in at-risk individuals. These results suggest a possible @entity1246 (A) dysfunction early in the disease course, whereas alterations in @entity1246 (B) functionality seem to occur later in the disease's progression. Future longitudinal studies will be needed to clarify this inhibitory deficit and its relation to the transition to @entity716 .

Deficient inhibitory cortical networks in antipsychotic-naive subjects at risk of developing first-episode XXXX and first-episode @entity161 @entity1 : a cross-sectional study.

@entity1 :: ('9606', 'Species') :: ['patients'] @entity161 :: ('MESH:D012559', 'Disease') :: ['schizophrenia'] @entity1246 :: ('MESH:D005680', 'Chemical') :: ['gamma-aminobutyric acid', 'GABA'] @entity716 :: ('MESH:D011605', 'Disease') :: ['psychosis']
@entity716 :: (MESH:D011605,Disease) :: ['psychosis']
