Recent findings suggest that temporal processing of brief durations is a function of dopaminergic neurotransmission in the basal ganglia. Furthermore, there is preliminary evidence of abnormal timing functions in patients suffering from idiopathic Parkinson's disease (PD). In the present study, temporal discrimination of intervals in the range of milliseconds was investigated in 20 PD patients and 20 healthy controls matched for sex and age. Temporal discrimination was significantly impaired in PD patients as compared to healthy controls. For PD patients, additional correlational analyses did not yield any significant relationship between performance on temporal processing and degree of motor impairment or illness duration. However, impairment in temporal processing was associated with dosage of L-dopa substitution and self-rated feelings of depression. The overall pattern of results suggests that deficits in temporal information processing observed in PD patients may represent a trait marker of vulnerability to decreasing levels of dopaminergic activity in the basal ganglia rather than a state-dependent indicator of the acute clinical symptomatology.

Motor dexterity under neuroleptic treatment is of particular interest to the patients concemed as it is essential in driving a car or working at high-tech machines (Hobi, 1983). Inpatients are often discharged when still on high-dose neuroleptic therapy in order to secure an early reintegration to family and working process. Insight into the differential impact oflong-tenn neuroleptie treatment on psychomotor and cognitive perfonnance is important in the search for agents with minimal effeets on the CNS system responsible for motor and sensomotor functioning. Hindmarch (1980), Hobi (1983), and Hoyos (1980 proposed procedures to investigate the psychomotor functions relevant for the examination of a person's ability to work at dangerous machines or to drive a car. Grübel-Mathyl (1987) found lower reaction time perfonnance in patients receiving antipsychotic agents; schizophrenie patients perfonned worse on attention tasks when compared to nonnal controls or depressed patients (Gerhard and Hob1 984; Grübel-MathylI986). In particular, agents like haloperidol with a strong impact on the nigrostriatal system led to a distinct psychomotor impairment, i. e. deteriorated attention perfonnance and temporal infonnation processing (Marder et aL, 1984). For Oupenthixol, when administered at 2 mg/day to male subjects, detrimental effeets on perceptual and psychomotor functions could be shown (Rösleret aL, 1986). Similarly, four hours after application to healthy volunteers complex motor movements were impaired by 50 mg c10zapine (Saletu et aL, 1987). However, Gerhard (1987) discussed peristatie factors inOuencing driving ability such as age, risk taking behavior, reactive aggressiveness, emotionallability, and alcohol consumption. In this paper we will report differential effeets ofvarious neuroleptic agents, i. e. haloperidol, Oupenthixol, and c1ozapine, on motor, sensorimotor, and cognitive perfonnance in schizophrenie patients. These neuroleptics were chosen on account of their different phannacodynamic effects: haloperidol as a more sedative, Oupenthixol as a moderately drive enhancing drug, and c10zapine as an agent without extrapyramidal sideeffects. Patients and MethodsN = 50 acute schizophrenic inpatients according to DSM-III and ICD-9 No. 295.1-295.3 were assigned to three types of neuroleptic treatment: 25 patients (9 females, 16 males, average age of 30.4 years) were treated with 10--30 mg haloperidol per day, 15 patients (8 females, 7 males, average age of 28.4 years) with 5-20 mg flupenthixol, and 10 patients (2 females, 8 males, aged 28.0 years on average) received 150--500 mg c10zapine per day. After giving infonned consent the patients treated with the above antipsychotics for 7 or more days underwent cognitive and sensorimotor perfonnance tasks, testing being done between 10 and 12 a. m. in order to control diurnal variations of performance. The psychometric test battery comprised the 'Motorische Leistungsserie' (MLS), measuring ann-hand-tremor (steadiness), precision and speed of motor skills (Iine tracing)...

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