The autonomic nervous system regulates functions in the body that are involuntary, such as blood pressure and digestion. This system malfunctions in LBD, causing problems with blood pressure regulation, urinary incontinence and constipation. Many studies have been done on autonomic dysfunction in Parkinson’s disease and multiple system atrophy, both of which also are characterized by the presence of Lewy bodies in the brain. Research demonstrates that autonomic dysfunction predicts a shorter survival time in these disorders. Little is known about how autonomic dysfunction affects survival in Lewy body dementias.
Dr. Kajsa Stubendorff of Lund University in Sweden and other researchers in Europe studied 30 individuals with dementia with Lewy bodies (16) and Parkinson’s disease dementia (14) in a prospective, longitudinal follow-up study. Three aspects of autonomic dysfunction were assessed: orthostatic hypotension (OH), urinary incontinence and constipation. OH is a form of low blood pressure occurring after a person stands up, often after prolonged rest. The change in position causes a temporary reduction in blood flow to the brain and symptoms which include dizziness, lightheadedness, blurred vision and fainting.
Participants’ blood pressure and heart rate were recorded at baseline, 3 months and 6 months. Blood pressure readings were taking in different positions: after the subject was lying down for at least 10 minutes, immediately upon standing up, and at one, three, five and ten minutes of standing. 83% had at least one measurement of OH and 50 percent had persistent OH over the course of the study. Urinary incontinence and constipation were assessed by asking questions of the patient and caregiver. 30 percent reported problems with urinary incontinence and 30 percent reported constipation requiring treatment.
Seven of the 30 patients died during the follow-up, five from the DLB group and two from the PDD group. Patients with persistent OH had a significantly shorter survival compared to those with no or non-persistent OH; there were, however, no differences in survival between those with or without constipation or urinary incontinence.
Subjects were divided up into three categories: those with no or mild OH (15), those with persistent OH but no urinary incontinence or constipation (7), and those with persistent OH, constipation and/or urinary incontinence. Patients in the third group had the shortest survival times, while those in the second group had the next shortest.
While people with OH may experience symptoms such as light-headedness, research shows that only 43 percent of non-demented patients with profound OH have typical symptoms. As such, orthostatic blood pressure measurements should be a routine part of monitoring all patients with Lewy body dementias. It is important to note that individuals with dementia may not show a significant drop in blood pressure until as late as 10 minutes after standing. Research indicates people with DLB have a more prolonged period of orthostasis after standing up than individuals with Alzheimer’s or health control subjects.
This is the first study to analyze how autonomic dysfunction affects survival in LBD. These results suggest that persistent autonomic dysfunction is possibly predictive of shorter survival time. Further research is needed to understand how autonomic dysfunction impacts other issues, such as quality of life, cognition, and activities of daily living.
This study first appeared in PLoS One in October, 2012.