This single-center, randomized, double-blind, four-period crossover study will investigate the effect of alcohol on the pharmacodynamics and pharmacokinetics of RO4917838 in healthy volunteers. Healthy volunteers will receive 4 treatments in a randomized order: single dose of RO4917838 and alcohol, RO4917838 and non-alcoholic drink, placebo to RO4917838 and alcohol, and placebo to RO4917838 and non-alcoholic drink.

Inclusion Criteria:

• Adult healthy volunteers, 18 to 45 years, inclusive
• Body Mass Index (BMI) 18 to 30 kg/m2, inclusive
• Non-smoker or smoker of fewer than 10 cigarettes per day
• Females, who are not menopausal must agree to use two adequate methods of contraception

Exclusion Criteria:

• Any current medical condition or disease that would render the volunteer unsuitable for the study, or would place the volunteer at undue risk
• History of alcoholism
• History of drug abuse and/or addiction within one year of study start
• History of any significant disease (e.g., cardiovascular, hepatic, renal) or cancer