Performance of diadochokinetic movements in schizophrenic patients

Motor deficits are common and disabling symptoms in schizophrenic patients, which have enormous impact on the long-term outcome of the disease by affecting work performance and daily functioning. They are attributed to the disorder itself, as well as to treatment with dopamine-blocking antipsychotics. This study assessed the kinematic parameters of motor performance of a diadochokinetic hand movement in 20 drug-naïve, 20 conventionally treated (haloperidol or fluphenazine), and 20 atypically treated (olanzapine) patients, as well as in 20 healthy controls using a three-dimensional ultrasonic movement analysis system. It also tested differences in motor enhancement as induced by an attentional strategy and in dexterity advantages of motor performance for the dominant hand between the four study groups. Amplitude and peak velocity of diadochokinetic hand movements were significantly reduced in all patient groups compared to the controls, while frequency of the repetitive movement remained unaffected. The reduction was most pronounced in the conventionally treated patients. In addition, movement automation was impaired, primarily under conventional antipsychotic treatment. The study also revealed weaker effects of an attentional enhancing strategy on the movement amplitude in atypically and conventionally treated patients compared to both controls and drug-naïve patients. Alterations of dexterity could not be detected either in the drug-naïve or in the treated patients. The results indicate that patients with schizophrenia suffer from a specific primary motor deficit in diadochokinesia with reduction of amplitude and peak velocity. This deficit is significantly worsened by conventional antipsychotic treatment. Antipsychotic treatment additionally reduces the enhancing effect of an attentional strategy on motor performance.