Ethanol Response in Essential Tremor: Clinical and Neurophysiological Correlates

Background:

• Essential tremor (ET) is a neurological disorder involving uncontrollable shaking, which over time can interfere with mobility and affect routine aspects of daily living. Several medications are used to treat ET, but these medications are often only partially effective and can have side effects. About two-thirds (66%) of people with ET have some relief from drinking alcohol, which suggests that alcohol affects the part of the brain causing the tremor. However, more research is needed to better understand the effects of alcohol or what areas of the brain might be important in the response.

Objectives:

• To study to what extent alcohol is reducing tremor in a group of patients with essential tremor.
• To use transcranial magnetic stimulation to study the effects of alcohol on essential tremor.

Eligibility:

• Individuals who are at least 21 years of age, have been diagnosed with essential tremor and have tremor in both hands, and can tolerate being off all medications for essential tremor for up to 4 weeks.

Design:

• This study has one screening visit (1 to 2 hours), followed by one study visit (3 to 5 hours). Participants might be asked to also take part in one additional study visit (3 to 5 hours). The maximum period between the study visits is 3 months.
• Participants will be screened with a medical history, physical examination, and blood tests. At this visit, participants will receive information about how to safely taper off their current ET medications before the start of the study.
• Participants must be willing to abstain from drinking any alcohol or caffeine (or consuming foods with caffeine such as chocolate) for at least 2 days before the study visits. Participants must also fast overnight (for at least 8 hours) before the study visits.
• At the first study visit, participants will receive a single drink of alcohol (mixed with a noncaffeinated drink) and will complete movement tests to determine whether the alcohol improves the tremor. Alcohol levels will be monitored throughout the visit.
• At the second study visit, participants will have an electrocardiogram to measure heart electrical activity and determine if they are able to safely have transcranial magnetic stimulation. Participants will then receive an intravenous infusion of alcohol and complete questionnaires during the infusion to provide information about its effects. Then, transcranial magnetic stimulation will be used to study brain electrical activity, as well as muscle movements and tremor activity, while under the influence of the alcohol infusion.
• After each study visit, participants will remain at the clinical center until the effects of the alcohol have worn off. Participants will be able to resume taking their ET medications after the end of the study.