Autonomic activity in relation to symptom ratings and reaction time in unmedicated patients with schizophrenia

Problem: High autonomic base levels and low responsivity are frequently observed in unmedicated patients with schizophrenia. We previously reported that patients in the present cohort, compared to normal controls, had high autonomic tonic baselines and low reactivity to the meaningful stimuli in a reaction time (RT) task but not to novel but innocuous stimuli. This paper explores further the role of autonomic activity in the pathogenesis of schizophrenia by relating differences in the autonomic variables among patients to symptom ratings and RT. Methods: Electrodermal activity and heart rate were recorded during rest, a tone series, and a RT task in 73 patients with schizophrenia taking placebo. Symptoms were rated with the Brief Psychiatric Rating Scale. Results: Patients with higher autonomic baselines both at rest and under mild stress and those with greater electrodermal responsivity to both simple tones and the RT stimuli had more severe positive, "active", and total Symptoms than patients with lower baselines and responsivity. RT was slower in patients with higher baselines. Conclusions: High autonomic activity in general, reactivity as well as base levels, under all conditions used in this study was associated with symptom severity independent of differences from controls. Thus elevated autonomic activity and responsivity may themselves be disturbing or index states that are disturbing in schizophrenia. Some patients might attempt to cope with novel or demanding situations and stimuli by a passive-avoidant strategy of low attention and effort in order to attenuate their responsivity. Less symptomatic patients may better cope in this manner. (c) 2005 Elsevier B.V All rights reserved.