Schizophrenia subgroups differing in dichotic listening laterality also differ in neurometabolism and symptomatology

Schizophrenia patients vary in right ear advantage (REA) on dichotic listen ing tests for assessing left hemispheric dominance for language processing. The authors examined if patients with low REA differed from other patients in symptoms and in resting brain metabolism. SPECT was conducted during vi sual fixation for 9 healthy control subjects and 16 schizophrenia patients: 8 with normal and 8 with diminished REA. REA-diminished patients had great er positive symptoms and lower mental status scores (all P<0.05) and had ri ght middle temporal gyrus hypermetabolism. Both schizophrenia groups had de creased right frontal and increased medial temporal lobe metabolism vs. con trol subjects. REA-diminished patients herd right temporal lobe hypermetabolism under a re sting condition (eyes open, visual fixation). Results suggest reduced right ear (left hemisphere) advantage for dichotic word perception in schizophre nia is related to a predisposition to overactivate right temporal lobe regi ons and to positive symptoms. In contrast, the prefrontal-medial temporal i mbalance present in both patient groups may typify the schizophrenia syndro me.