Autonomic and cognitive dysfunction in Parkinson's disease

Objective To investigate whether there is an association between autonomic failure and cognitive impairment in patients with idiopathic Parkinson's disease (PD) Methods 40 PD patients and 30 age matched controls were assessed for cognitive and behavioral manifestations using the Mini-Mental State Examination (MMSE), the Frontal Assessment Battery (FAB), the Blessed scale and Cornell scale for depression. The subjects were also assessed for orthostatic hypotension (OH), postprandial hypotension (PPH), heart rate responses to deep breathing (HRDB) and autonomic symptoms using the Scale for Outcomes in PD for autonomic symptoms (SCOPA AUT). Results There was a correlation between the severity of motor symptoms and cognitive impairment in our PD patients. Eleven of the 40 PD patients fulfilled the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria of dementia. The presence of OH or PPH did not correlate with the severity of cognitive impairment in our PD cases. However, PD patients with dementia reported more cardiovascular symptoms than PD patients without dementia. There was no correlation between gastrointestinal or urologic symptoms and cognitive impairment in our PD cases. Conclusion The results of this limited study indicate that despite the higher incidence of cardiovascular symptoms in PD patients with dementia than in those without dementia, there is no consistent association between OH or PPH and cognitive deficits in PD. The lack of correlation between OH, gastrointestinal and urinary symptoms with cognitive impairment suggests that cognitive and autonomic involvement progresses independently from each other and variably among PD patients.