Pregabalin in the Treatment of Essential Tremor

Overview We propose a single site, double-blind, placebo-controlled, cross-over design. Drug will be administered in 75mg capsules with a target dose of 300 mg/day. Pregabalin will be titrated upward as described in the "Summary of Schedule" table with flexibility. During weeks 3-5 and 12-14, the investigator will have the option of increasing the study drug from 2 capsules per day (150 mg vs. placebo) to 3 or 4 capsules per day if no benefit is noted. If the dose is increased, it must be done so at a rate of 150mg/day/week. Patients who can not tolerate a higher dose will be allowed to drop back to a previously tolerated dose but must be on that dose for one week prior to evaluation. After treatment and clinical assessment, study drug will be decreased by 150mg/day every 2 days until discontinuation. This pertains to both the wash out phase and at the end of the study. Both adverse events and need for drug titration will be conducted during the safety call. Identical assessments will be done at baseline and at the end of the treatment period for both drug and placebo. Half of the subjects (group A) will initiate with placebo and then crossover to drug. The other half (group B) will start treatment with pregabalin and then crossover to placebo. The primary endpoint will be the change in Fahn-Tolosa-Marin Tremor Rating Scale (TRS) from baseline. Scale has Parts A= (severity of rest, action \& postural tremor in upper and lower extremities, face, voice, tongue, head \& trunk), B= (severity of tremor writing, drawing \& pouring), C= (functional disability while speaking, eating, drinking, maintaining hygiene, dressing \& working) and the total summed. Other clinical assessments will include Clinical Global Impression of Change (CGI-C), Quality of Life in Essential Tremor Questionnaire (QUEST) maximum score =100, Hamilton Anxiety Scale (HAM-A) score 0-17 = mild, 18-24 = moderate, and 25-30 moderate to severe, and a sleep hygiene questionnaire rating across 5 domains- physical symptoms, energy \& motivation, concentration, interpersonal relations, and psychological symptoms (HD-16). For the TRS, HAM-A, QUEST, and HD-16 higher scores represent increased symptom severity or diminished quality of life and the CGI-C is scored as follows: 1=very much improved, 2=much improved, 3= mildly improved, 4=no change, 5= mildly worse, 6= much worse, and 7=very much worse.