The present work deals with the effects of psychotropic drug therapy on the operation of psychomotor functions used in a clinical examination of suspected drunken drivers. 100 psychiatric mental, but otherwise healthy, patients were examined; the type of medication and the number of drugs used varied greatly. In 71 cases the mean degree of error in the clinical examination was higher, and, in several of these, markedly higher than the reference values obtained earlier on suspected drunken drivers when the blood contained very small amounts of alcohol or none at all. In 18 cases coarsely-divided nystagmus was registered in patients on psychotropes. This is an obvious sign of a marked side-effect of medication but was present more infrequently than in subjects with after ingestion of alcohol.
The present results indicate that application of the clinical examination method, which was originally developed for and related to the examination of alcohol cases, to subjects on psychotropes is adequate, and it is possible with clinical examination to obtain valuable medicolegal information on the impairment of physiological functions. The present review of suspected drugged drivers examined in Helsinki in 1969-1972 also supports this view.