Methods of treating mental disorders, including anxiety disorders such as obsessive-compulsive disorder, are provided. The methods comprise administering an effective amount of a glutamate modulator to an individual in need thereof. Also provided are methods of enhancing the activity of a serotonin reuptake inhibitor (SRI) comprising co-administering a glutamate modulator and a serotonin reuptake inhibitor. Pharmaceutical composition comprising a serotonin reuptake inhibitor and a glutamate modulator are also provided.
