Asymmetry of lexico-semantic processing in schizophrenia changes with disease progression.
Lam M., Collinson SL., Sim K., Mackay CE., James ACD., Crow TJ.
BACKGROUND: Are anomalies of cerebral asymmetry integral to the disease process? Here, we examined the influence of age, chronicity and age of onset of illness in 34 patients with early onset schizophrenia and 20 controls in relation to structural asymmetries of the temporal lobe and performance asymmetries on a semantic language lexical decision task. METHODS: Volumetric MRI and a novel divided visual field probe of lateralised lexico-semantic language were assessed in patients with early onset schizophrenia (EOS) and controls. Novel ratios of age-illness overlap and directional asymmetry were developed in order to examine the association of chronicity factors to asymmetry. RESULTS: Loss of laterality on the lexical decision task and discordant structural asymmetry were correlated with duration of illness but were not seen in younger, less chronic patients. Reduced lateral processing speed, and discordant structural asymmetry were associated with greater proportion of lifetime schizophrenia. CONCLUSION: Although the conclusions are limited by the cross sectional nature of the study, anomalies of cerebral asymmetry in early onset patients may be an index of disease progression, and reflect directly on the disease process.