Sociopsychological factors influencing response to levodopa therapy for Parkinson's disease

This article examines the effect of a series of physical and sociopsychological variables on the response shown by Parkinson patients to levodopa therapy. Of the ten major variables examined, six measure relatively enduring personality adaptations: suggestibility, passivity, self-expectations, stigma, attitudes toward illness, and the perception of the expectations of others. Four are illness-related characteristics: diagnosis (primary or secondary parkinsonism); the existence of health problems in addition to Parkinson's disease; whether or not the patient was hospitalized at the beginning of treatment; and symptom improvement as rated by the patient's physician. Age, sex, severity and duration of disease, and use of anti-Parkinson drugs in addition to levodopa were controlled in all of the analyses. The effect of levodopa therapy was assessed in four major areas: activity, social participation, depression, and enjoyment of life. Findings can be summarized as follows: Five of the six personality variables do, in fact, modify the amount of social or psychological change shown by Parkinson patients treated with levodopa. The only one which fails to have such an effect is passivity; this may reflect a measurement problem. However, only two of the four illness-related characteristics which were examined made a difference in treatment outcome: diagnosis and symptomatic improvement, as rated by the patient's physician.