Assessing the Relationship Between ET and Dementia

IETF Funded Research

Principal Investigator: Shyamal Mehta, MD, PhD. assistant professor of neurology at the Mayo Clinic, Arizona

PROJECT SUMMARY

Specific Aims:
Essential tremor (ET) is a common neurological condition which increases in prevalence with age and contributes to significant disability by interfering with activities of daily living (ADLs) in most affected patients. Dementia is another common neurological condition of varying etiologies – most commonly Alzheimer’s disease, vascular dementia and Lewy body disorders to name a few. A population study of ET demonstrated that more mildly affected, largely untreated ET individuals may be more likely to complain of memory problems and have deficits at testing (1). In the past, our group has compared the risk of developing dementia in subjects with ET versus controls without tremor in a large, well characterized cohort of individuals involved in a longitudinal aging study, the Arizona Study of Aging and Neurodegenerative Disorders (AZSAND) (2). Based on the size of our cohort at the time, we concluded that ET was not associated with an increased risk of dementia but that a subset of subjects with older age onset/shorter duration tremor may be at higher risk. We would like to better assess and further study this more conclusively given the substantial increase in the size of our ET cohort since our first report, thanks in part to funding from the IETF. As well we propose to better characterize the tremors in patients with dementia related to both Lewy body and non-Lewy body disorders.

Aim 1: To evaluate the risk of developing dementia in patients with ET

Here we intend to compare the risk of developing dementia in subjects with ET versus controls without tremor or other neurological condition in our large, well-categorized cohort of individuals involved in a longitudinal aging study (AZSAND). All subjects are followed annually with a comprehensive standardized motor and neuropsychological test battery to assess cognitive function as well as clinical evaluations for tremors by a trained movement disorders specialist.

Aim 2:To determine the prevalence and characteristics of tremors in patients with dementia related to Lewy body disorders vs. non-Lewy body disorders

Relatively little is known regarding the prevalence and characteristics of tremors in patients with dementia. We will assess the overall presence of postural and action tremors in patients with dementia and further compare the tremors in dementia patients with Lewy body disorders (Parkinson’s disease, dementia with Lewy bodies and multiple system atrophy) to non-Lewy body disorders (Alzheimer’s Disease, vascular dementia and progressive supranuclear palsy).