Freezing of gait subtypes have different cognitive correlates in Parkinson's disease

BACKGROUND

Freezing of gait (FOG) is a major concern for Parkinson's disease (PD) patients because it is a leading cause of falls and is associated with poor quality of life. The pathophysiology is unknown but it is hypothesized that it relates to cognitive abnormalities; particularly executive and visuospatial dysfunction. However, prior results have been discrepant. Pharmacologic subtypes of FOG include those that are responsive and unresponsive to levodopa.

OBJECTIVE

To determine whether executive and visuospatial dysfunction are associated specifically with the levodopa unresponsive subtype of FOG.

METHODS

135 PD subjects completed a single assessment included FOG questionnaire, UPDRS motor scale, comprehensive cognitive battery and measure of hallucinations. Analyses compared unresponsive (n = 16), responsive (n = 20) and no FOG (n = 99) subtypes.

RESULTS

The unresponsive subtype had a significantly older age of onset of PD than the responsive group (p = .03) and had worse motor scores (p = .003) than the no FOG group. Longer disease duration was associated with the responsive group compared to the no FOG group (p = .002). The unresponsive FOG group had significantly poorer visuospatial ability (p = .001) and executive functioning (p = .02) than both the no and responsive FOG subgroups. These latter groups were not significantly different. The responsive FOG group was associated with the presence of hallucinations.

CONCLUSION

Aside from pharmacological differences, unresponsive FOG is associated with executive and visuospatial dysfunction implicating frontostriatal pathways while responsive FOG is associated with hallucinations suggesting involvement of posterior cortical regions. Further study and treatment of FOG should include appropriate subtype classification.

Neuroleptic exposure in bipolar outpatients in a research setting

The study purpose was to determine the extent of neuroleptic exposure in bipolar outpatients maintained on mood-stabilizing medications and any clinical correlates associated with this exposure. Data on medication and severity of illness were gathered from the records (prospective and retrospective) of 70 bipolar patients involved in outpatient research studies at the National Institute of Mental Health (NIMH). The percentage of patients requiring neuroleptic treatment, percentage of time on neuroleptics during the period of observation, total dose of neuroleptics in chlorpromazine (CPZ) equivalency, and number of neuroleptic trials were among the variables calculated. Regression analyses and analyses of variance (ANOVAs) were performed to assess the relationships between neuroleptic exposure and clinical course. Forty-five patients (64.3%) had a neuroleptic trial during the prospective study. Subjects exposed to neuroleptics spent, on average, 15.4% (median, 6.0%) of the time in study on neuroleptic treatment, and were administered, on average, a total of 11,770.5 mg (median, 1,621.9 mg) of neuroleptics (in CPZ equivalency) per year in the prospective study. As expected, bipolar I compared with bipolar II patients had significantly higher neuroleptic exposure by a number of measures. The number of hospitalizations for mania prior to study entry was associated with greater prospective neuroleptic use during the study. Despite maintenance treatment with one or more moodstabilizing agents, we found a relatively high need for adjunctive neuroleptic medication even in this sample of high-functioning bipolar outpatients. These results highlight the need for the study of alternatives, as well as more effective primary mood-stabilizing agents.