This open-label, fixed sequence, two-period study will assess the effect of memantine on the pharmacokinetics, safety and tolerability of a single oral dose of RO5313534 and the effect of RO5313534 on safety and tolerability of steady-state memantine. Healthy volunteers will receive a single oral dose of RO5313534 on Day 1 of Treatment Period 1 (3 days). After a washout period of 5-21 days, oral memantine will be administered on Days 1-21 of Treatment Period 2 and a single dose of RO5313534 on Day 19. There will be a follow-up of 3-4 weeks after the last dose. Anticipated time on study for each volunteer is up to 14 weeks.

Inclusion Criteria:

• Healthy males and females, 18 to 45 years of age inclusive
• Body mass index (BMI) 18-30 kg/m2
• Male subjects must agree to use a barrier method of contraception from first dosing until the end of the study
• Female subjects must be either surgically sterile or agree to use two forms of contraception until the end of the study
• Non-smoker for at least 6 months

Exclusion Criteria:

• Clinically significant history or detection during medical interview/physical examiation of any disease or condition that is capable of altering the absorption. metabolism or elimination of drugs, or would constitute a risk factor when taking the study drug
• History of drug addiction or alcohol abuse
• Any confirmed significant allergic reaction to any drug, or multiple allergies in the judgement of the investigator
• Positive serology to hepatitis B or hepatitis C or Human Immunodeficiency Viruses (HIV type 1 and 2) at screening
• Pregnant or lactating women
• Participation in an investigational drug or device study within the last 3 months prior to first dose