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The primary purpose of this study was to examine motor physiology disturbances in a group of patients with bipolar disorder by using sensitive instrumental procedures. The secondary aim of the study was to examine the effects of the affective state on motor functions. The authors studied 67 individuals meeting DSM-IV criteria for bipolar disorder and 47 healthy comparison subjects. Electromechanical measures of force steadiness and scaling of movement velocity to distance were performed. The authors found that performance on the force steadiness and velocity scaling measures was significantly poorer in the subjects with bipolar disorder, with 58% and 63% of the patients scoring outside the normal range on the force steadiness and velocity scaling measures, respectively. Eighty-four percent of subjects showed impairment on either measure, and 37% showed impairment on both measures. The force steadiness and velocity scaling abnormalities appeared to occur independently of one another and also were not associated with affective state or current medication status. This study demonstrates that motor abnormalities suggestive of basal ganglia dysfunction occur in many patients with bipolar disorder.

Neurobehavioral disturbances often coexist with extrapyramidal signs (EPS) in patients with Alzheimer's disease (AD). In the present study, we examined the relationships between delusions and hallucinations and EPS by using standard observer ratings and sensitive electromyographic (EMG) measures in 52 patients with probable AD. On the basis of observer ratings, 36.5% of the patients exhibited psychotic features and 63.5% exhibited parkinsonism. Severity of clinically rated parkinsonism and the EMG measure of bradykinesia were significantly correlated with severity of neurobehavioral disturbances in this sample. The association between parkinsonism and delusions and hallucinations suggests a subcortical mechanism in the etiopathology of psychosis in AD.

Previous studies suggest that many untreated schizophrenia patients exhibit motor disturbances. On the basis of these findings, the authors hypothesized that preexisting extrapyramidal movement disorders may increase the risk of developing neuroleptic-induced parkinsonism (NIP). Thirty-five newly medicated psychotic patients underwent pretreatment clinical and instrumental motor and psychiatric assessments. Posttreatment ratings of parkinsonism were conducted at monthly intervals for the first 3 months and every 3 months thereafter. Thirteen patients (37%) developed NIP. Advanced age and pretreatment extrapyramidal disturbances predicted NIP. Life-table survival curves indicated that patients with pretreatment instrumental rigidity developed clinically significant NIP earlier than those without rigidity. These findings suggest that pretreatment motor dysfunction may be a risk factor for drug-induced parkinsonism, especially among older patients.

The authors examined severity of dyskinesia in 119 men and 44 women, comparing by gender those with late-onset schizophrenia (LOS) versus early-onset schizophrenia (EOS). Women with LOS and men with EOS had more severe dyskinesia than men with LOS and women with EOS. Many factors, including the length of neuroleptic treatment, alcohol and smoking history, and menopausal status, may contribute to the severity of dyskinesia in older patients with schizophrenia.

The results of a new procedure for the quantification of tardive dyskinesia (TD) in the hand are reported. Fourier analyses were made of steady-state isometric force control in 41 neuroleptic-treated patients with and without hand TD. Results indicated that spectral analysis of isometric posture represents a reliable, sensitive, and valid measure of neuroleptic-induced dyskinesia.