Aaron Artiles1,2, Dietrich Haubenberger MD1, Bernard Voller MD1, Emily Lines BA1, Gayle McCrossin RN1, Vijay Ramchandani PhD3, Vatsalya Vatsalya MD3, Sherry Vorbach1, Sule Tinaz MD1, Mark Hallett MD1
1Human Motor Control Section, Medical Neurology Branch, NINDS/NIH, Bethesda, MD
2Boston College, Chestnut Hill, MA
3Laboratory of Clinical and Translational Studies, NIAAA/NIH, Bethesda, MD
Background: Essential Tremor (ET) is a common movement disorder characterized by action tremor mainly involving arms and hands in 95% of ET patients. Tremor is less common in other parts of the body including head, face, legs, and voice. According to historical information, alcohol (ethanol) is known to suppress these movements in approximately two thirds of ET patients. Tremor can be measured objectively using neurophysiological techniques such as digital spiral analysis. The aim of this study was to investigate whether ethanol-consumption during the 3-month period prior to the study differs between ET patients defined as ethanol responders and non-responders. Furthermore, we investigated subjectively rated non-tremor effects of ethanol in patients with ET and again compared responders versus non-responders.
Methods: Under a protocol investigating the neurophysiological correlates of the ethanol-response in ET (CNS IRB #10-N0199), 54 patients diagnosed with Essential Tremor were asked to consume a standardized drink of 95% ethanol (dose calculated using total body water estimate, diluted 1:3 with a vehicle) with the goal of reaching a peak blood alcohol content (BAC) of 0.05 g/dl. Frequency and amplitude of the tremor was measured objectively using digital spirography as described before (Haubenberger et al, 2011). Patients drew spirals on a tablet PC using custom software (Neuroglyphics). Patients were asked to draw spirals on the tablet before, and every 20 minutes following alcohol administration. Response to ethanol was defined as a 35% or more decrease in tremor amplitude of the dominant hand at the 60-minute time point compared to the baseline amplitude. Before the experiment, the patient was asked to complete a calendar estimating the number of drinks consumed on each day for the three months prior to the study (Time Line Flow Back, TLFB). Furthermore, patients were asked to complete standardized questionnaires on biphasic effects of ethanol (BAES), as well as general drug effects (with alcohol being the drug, “Drug Effects Questionnaire”) and urge to drink alcohol (Alcohol Urge Questionnaire), every 20 minutes during the study after administration. Patients with hazardous alcohol consumption or possible alcoholism (defined per AUDIT score of ≥8) were excluded from the study.
Results: The data suggests that there is a trend that ethanol responders consumed more alcoholic drinks and drank more frequently than non-responders, although this data is not statistically significant. There was no difference in the three self-reported drug effects categories between the responders and non-responders at the 60-minute time point when response was determined.
Discussion: Our results suggest that ethanol responders consumed a larger quantity of alcohol during the three months prior to the study in comparison to non-responders, although the difference was lacking statistical significance. If true, a possible explanation would be that responders might have a higher intake of alcohol due to the fact that alcohol improves their tremor. However, our results do not suggest any difference in subjective response to alcohol in non-tremor domains between responders and non-responders. The lack of statistical significance of the difference in the TLFB data might be due to the high variability of drinks consumed by patients as well as the small number of non-responders (10) compared to the number of responders (44).
Last updated December 14, 2012