Selectively impaired reaction time in Parkinson's disease: persistent absence of simple reaction advantage in a patient with frontal complications.

The search for specific patterns of impaired reaction time in Parkinson's disease has yielded conflicting results. We propose subtypes that exhibit different patterns of impairment and report the case of a patient, Jobe, whose simple and binary choice reaction times were tested repeatedly in a variety of stimulus-response paradigms over a period of 4 years. Jobe consistently failed to exhibit the normal simple reaction advantage even though his choice reaction times fell well within the normal range. While his general intellectual status was above average, he had great difficulty with some neuropsychological tests. He was seldom able to acquire a new category in the Wisconsin Card Sort Test and also had difficulty with the Tower of London Test. We ascribe Jobe's selective impairment of simple reactions to an inability to engage in the off-line preparatory processing that confers an advantage on simple reactions.