AbstractThis study aimed at identifying patterns or clusters of functional impairment and behavioural disturbances in vocally disruptive patients compared with controls. Identified vocally disruptive patients (37) from psychogeriatric wards (264 patients) were included and compared with controls (37) matched for sex and wards. Assessment of the degree of orientation and functional performance (physical and psychosocial) was made using a newly developed rating scale, Organic Brain Syndrome Scale, consisting of two subscales, a 16‐item scale measuring orientation and a 39‐item scale measuring functional performance. Principal component analysis was applied reducing the first subscale into three factors (orientation to time, person, past and present events) and the other subscale into seven factors (functional performance and orientation in the ward, fluctuations in mental state and emotional disturbances, speech performance and psychomotor slowing, mobility, hostility, presence of delusions and hallucinations, sensitivity and euphoric state). Discriminant analysis revealed that vocally disruptive behaviour related significantly to physical dependence and disorientation in the ward, confusional reactions, delusions, hallucinations and a more preserved speech performance compared with controls. Suggestions have been made that vocally disruptive behaviour develops when environmental factors such as sensory deprivation interact with the effects of the brain dam