Differential relationship of frontal pole and whole brain volumetric measures with age in neuroleptic-naïve schizophrenia and healthy subjects.

Brodmann's area (BA) 10, which occupies the frontal pole (FP) of the human brain, has been proven to play a central role in the executive control of cognitive operations. Previous in vivo morphometric studies of the FP have been limited by the lack of an accepted boundary of its posterior limit. We studied the FP gray matter volume in 23 healthy subjects who were age-, sex-, and education-matched to 23 neuroleptic-naïve recent-onset schizophrenia subjects in the age span 20-40 years, using a cytoarchitectonically and functionally valid landmark-based definition of its posterior boundary that we proposed recently (John, J.P., Yashavantha, B.S., Gado, M., Veena, R., Jain, S., Ravishankar, S., Csernansky, J.G., 2007. A proposal for MRI-based parcellation of the frontal pole. Brain Struct. Funct. 212, 245-253. 2007). Additionally, we examined the relationship between FP volume and age in both healthy and schizophrenia subjects to examine evidence for a possible differential relationship between these variables across the samples. A major finding of the study was the absence of a group-level difference in frontal pole gray volumes between the healthy and schizophrenia participants. However, a more complex finding emerged in relation to age effects. The healthy participants showed an inverse relationship of FP gray volume with age, even after taking total brain volume differences into account. But this age effect was completely absent in the schizophrenia group. Moreover, all the volumetric measures in schizophrenia subjects showed substantially higher range, variance, skewness and kurtosis when compared to those of healthy subjects. These findings have implications in understanding the possible role of FP in the pathophysiology of schizophrenia.