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Abstract
An interesting aspect of the method used by Mavrogiorgou and co-workers10 is its potential to differentiate between various types of motor abnormalities. Indeed, on simple motor tasks OCD patients had higher peak velocity than controls, whereas on more complex tasks OCD patients had poorer hand motor performance and patients with late-onset had less automatisation of letter sequences. The researchers suggest that the former finding is consistent with overlearned primitive behaviour patterns; indeed, it is reminiscent of a range of studies noting increased impulsivity in OCD (perhaps unexpected in a compulsive disorder).2,12 Decreased automatisation would, however, arguably be consistent with work demonstrating impairment in implicit cognitive tasks in OCD.13 It might well be informative to extend this work to carry out detailed comparisons of handwriting abnormalities between CSTCmediated "hypophrenic" disorders (ie, those with difficulties in the development and maintenance of behavioural sets, such as Parkinson's disease) and "hyperphrenic" disorders (such as OCD), in which there are difficulties in relinquishing preferential sets of behaviour.