Volumetric brain regions and their relation to cognitive function : a family study on schizophrenia. Schizophrenia research

Abstract

We explored, in a sample of 188 individuals, the putative neural substrates of intelligence, memory and executive processing, while examining whether the pattern of function/structure relationship is different in schizophrenic patients (n=56) and their relatives (n=85) from that of controls (n=47). MRI data were acquired using a single 1.5 Tesla General Electric Signa System. Volumetric measurements were made on spoiled-gradient images employing a software package that uses stereological principles, and were obtained for Whole Brain Volume (WBV), Prefrontal region (PFR), Leteral Ventricles (LV), Third Ventricle (3rdV), R/L Temporal Lobe (rTL/ITL), R/L Hippocampus (RHp/LHp) and Cerebellum (CER). Full IQ (FIQ) and verbal IQ (VIQ) correlated with WBV (FIQ r.28, p.005; VIQ r.28, p.004), and RHp (FIQ 1".31, p.001 ; VIQ r.26, p.008). The latter was also associated with Performance IQ (PIQ) (r.28, p.005). Left Hippocampal size was predictive, in the expected direction, of VIQ, and in controls and relatives only, of FIQ (Con r.35, p<.001; Rel 1".36, p<.00t) and PIQ (Con r.21, p.004; Rel 1".37, p<.001). Verbal memory was linked to CER (r.25, p.01), and inversely to LHp (-.27, p.006). Visual memory was also associated, in relatives only, with the CER (r.32, p.00 l)and the LHp (r.35, p<.001 ). These data suggest (1) a dissociation between LHp and FIQ/PIQ in schizophrenia, indicating a loss of normal structure/function relationship, which may reflect a functional compensation, occuring as a result of an early brain insult. Since the dissociation does not extent to relatives, it is presumed that the pattern is related to the pathophysiology of schizophrenia per se; and (2) the relatives use different pathways to process visual information, perhaps, reflecting a variation in encoding strategy which may be the result of a compensatory process with a beneficiary effect.