Background: There are no studies of autonomic function comparing Alzheimer's disease (AD), Vascular dementia (VAD), Dementia with Lewy Bodies (DLB) and Parkinson's disease dementia (PDD).
Aims: To assess cardiovascular autonomic function in 39 AD patients, 30 VAD, 30 DLB, 40 PDD and 38 elderly controls by Ewing's battery of autonomic function tests and power spectral analysis of heart rate variability. To determine the prevalence of orthostatic hypotension and autonomic neuropathies by Ewing's classification.
Results: There were significant differences in severity of cardiovascular autonomic dysfunction between the four types of dementia. PDD and DLB had considerable dysfunction. VAD showed limited evidence of autonomic dysfunction, and in AD, apart from orthostatic hypotension, autonomic functions were relatively unimpaired. PDD showed consistent impairment of both parasympathetic and sympathetic function tests in comparison with controls (all p<0.001), and AD (all p<0.03). DLB showed impairment of parasympathetic function (all p<0.05) and one of the sympathetic tests in comparison with controls (orthostasis; p=0.02). PDD had significantly more impairment than DLB in some autonomic parameters (Valsalva ratio-p=0.024, and response to isometric exercise-p=0.002). VAD patients showed impairment in two parasympathetic tests (orthostasis; p=0.02, Valsalva ratio p=0.08) and one sympathetic test (orthostasis; p=0.04). These results were in contrast to AD patients who only showed impairment in one sympathetic response (orthostasis; p=0.004). The prevalence of orthostatic hypotension and autonomic neuropathies was higher in all dementias than in controls (all p<0.05).
Conclusion: Autonomic dysfunction occurs in all common dementias but is especially prominent in PDD with important treatment implications.
Allan LM, Ballard CG, Allen J, Murray A, Davidson AW, McKeith IG, Kenny RA. Autonomic dysfunction in dementia. Journal of Neurology, Neurosurgery and Psychiatry 2007;78:671-677.
Adrian Davidson, RVI Unit, Newcastle upon Tyne. Tel: +44 (0)191-233-6161.
Regional Medical Physics Department, Newcastle General Hospital, Newcastle upon Tyne, NE4 6BE, UK.
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