Syndromes of schizophrenia and schizotypy, hemispheric imbalance and sex differences: implications for developmental...

Progress is reviewed on the elucidation of the neuro-psychophysiological basis of a three-syndrome model of symptom expression in schizophrenia (Active, Withdrawn, Unreality), the first two syndromes of which were associated with an imbalance in activity between the hemispheres (Gruzelier, 1984). Recent work has discovered a similar three-syndrome structure to schizotypy in the normal population, and in keeping with the activation connotations of the Active and Withdrawn syndromes differences on self-report arousal scales were found. The same syndromes in normals were also associated with handedness, unlike the third Unreality syndrome which cognitive measures have shown to be inconsistently lateralised. Gender is known to be of fundamental importance to the form and expression of schizophrenia. Here sex differences had an important bearing on the syndrome-hemispheric imbalance relations which were stronger in males, while females had higher scores on the Unreality syndrome. Cognitive asymmetry patterns measured with recognition memory tests of lateralised temporoparietal functions disclosed a word > face cognitive asymmetry in females and a face > word asymmetry in males; asymmetries which were found to characterise androgynous individuals and feminine males. The results are in keeping with the relevance of the temporoparietal region to sexual dimorphism in brain structure and function, and by virtue of hippocampal connections, possible influences of hormones on brain development.