Psychomotor disturbance in depression: defining the constructs.

Four hundred and thirteen depressed patients were rated on eighteen signs of psychomotor disturbance, and the data examined by factor analyses. A three-factor solution was favoured. In addition to 'retardation' and 'agitation' dimensions (whose derived factor scores suggested independence of those two dimensions), a third 'non-interactive' dimension was evident--with derived factor scores correlating significantly with both the retardation and agitation dimensions. Thus, a 'trunk and branch' analogy was suggested for construing psychomotor disturbance, with a truncal 'psychic' component arborising into retardation and agitation 'motoric' expressions. Higher scores on all three factors were significantly linked with features weighted more to the melancholic 'type' of depression.