Obsessive compulsive and related disorders
OCD involves intrusive, unwanted thoughts and repetitive behaviors or mental rituals performed to ease the distress, taking up time and peace of mind.
Obsessions are persistent intrusive thoughts, images, or urges that feel alien and distressing. Compulsions are the repetitive behaviors or mental acts done to neutralize them: checking, washing, counting, seeking reassurance. The cycle can consume hours a day, and many people suffer quietly out of shame.
OCD is well understood and treatable. OCD involves loops between brain regions that generate doubt and urge, and SSRIs, often at higher doses than used for depression, help quiet those loops by increasing serotonin activity. That makes intrusive thoughts less sticky and rituals feel less urgent. Exposure and response prevention therapy works alongside it by teaching the brain that the feared outcome does not arrive when the ritual is skipped. With the right approach, most people see meaningful improvement.
Research and further reading
A few key papers behind how this condition is understood and treated today. Links open the abstract on PubMed, a free public database from the U.S. National Library of Medicine.
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Tseng et al. · Acta Psychiatr Scand · 2025
Across 34 trials and nearly 1100 participants, high frequency deep TMS over the medial frontal and cingulate region and rTMS over the dorsolateral prefrontal cortex produced the largest symptom reductions, with dropout rates similar to sham treatment.
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Cohen et al. · British Journal of Psychiatry · 2025
Analysis of 11 placebo controlled trials in 2372 adults showed that SSRIs lowered OCD symptom scores, with patients on an SSRI more than twice as likely to reach a meaningful response, while overall dropout rates were similar to placebo.
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Naderi et al. · Psychiatry and Clinical Neurosciences · 2019
In a 12 week trial of 100 adults with moderate to severe OCD, adding amantadine to the SSRI fluvoxamine improved obsession and overall symptom scores more than adding placebo.
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Saha et al. · Indian J Psychiatry · 2025
The authors report that doses above the usual maximum may improve symptoms in people whose OCD did not respond to standard treatment, while close monitoring is needed because side effects can occur.
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Eghdami et al. · Front Psychiatry · 2024
Across six trials with 195 adults, adding NAC to ongoing SSRI therapy modestly lowered OCD symptom scores with no increase in adverse events compared to placebo, though longer studies are still needed.
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Mindfulness for obsessive-compulsive disorder: a systematic review and meta-analysis
Perin et al. · Brazilian Journal of Psychiatry · 2026
Across six randomized trials, mindfulness based treatments reduced OCD symptoms as well as established CBT including exposure and response prevention, with equal dropout rates in both groups.
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Exner et al. · Journal of Anxiety Disorders · 2024
In a randomized trial of 74 outpatients, metacognitive therapy reduced OCD symptoms as well as exposure and response prevention by end of treatment, and both groups showed similarly low dropout.
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Memantine Augmentation in Obsessive-Compulsive Disorder: A Systematic Review and Meta-analysis
Lyndon et al. · CNS Drugs · 2026
Pooling six trials, this review found that adding memantine to standard treatment did not clearly reduce OCD symptoms more than placebo, so it is not supported for routine use.
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Mirzazadeh et al. · BMC Psychiatry · 2025
Both groups improved on escitalopram, and adding memantine offered no extra symptom benefit apart from time management.
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Zemestani et al. · Behavior Modification · 2022
Adding either talk therapy approach to a stable SSRI dose produced larger symptom reductions than staying on the SSRI alone.
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