Obsessive-Compulsive Disorder

A condition of intrusive, unwanted thoughts, images, or urges (obsessions) paired with repetitive behaviours or mental rituals (compulsions) performed to neutralise the anxiety they create. OCD is highly treatable — exposure and response prevention therapy is the gold standard — and it is about anxiety regulation, not personality or character.

Evidence synthesis: ERP has the strongest evidence base of any OCD treatment, with large effect sizes in randomised trials; SSRIs at higher doses are the first-line pharmacological option, and combination outperforms either alone for moderate-severe OCD. N-acetylcysteine (NAC), a glutamate-modulating antioxidant, has several randomised trials as an augmentation to SSRIs, with a meta-analysis showing modest benefit overall but inconsistent individual trial results — promising rather than established. Milk thistle and valerian have single small trials each and cannot be recommended. A key clinical insight with strong empirical support: compulsions and reassurance-seeking provide short-term relief while strengthening the obsession long-term, which is why ERP — deliberately resisting the ritual — works.