Electrophysiological examination of Formal Thought Disorder in schizophrenia

Quantitave EEG profile was recorded for 60 age and sex matched drug free/naive schizophrenia patients, divided into two groups based on the presence and absence of Formal Thought Disorder (FTD) and a group of 30 matched healthy participants. Coherence and power spectrum analysis revealed that as compared to normal controls, schizophrenia patients with FTD had decreased regional power and intra hemispheric coherence; those without FTD had increased regional power and increased intra hemispheric coherence. Inter hemispheric coherence was greater in schizophrenia patients with FTD and lesser in those without FTD, as compared to healthy participants. The data were interpreted in terms of neural dis-connection which in FTD can be attributed to the existence of both a deficit and excess of neural connections, which compensate each other.

► A large sample of drug free/naïve schizophrenia patients (N = 60) is a strong point of this study, EEG being vulnerable to psychotropic medication.
► EEG data was recorded over 60 scalp positions permitting higher spatial as well as temporal resolution.
► Excitability of the cortex is related directly to intra-hemispheric connectivity and inversely to inter-hemispheric connectivity.
► Attenuated regional functional interaction co exists with strengthened inter regional functional interaction and vice versa, suggesting generalized “aberrant connectivity”.
► FTD is inefficient top down regulation of experience and behaviour by the context; engendered by disequilibrium in the brain plastic process.