Clinical meaning
OCD is characterized by recurrent, intrusive, unwanted thoughts (obsessions) and repetitive behaviors or mental acts (compulsions) performed to reduce the anxiety caused by obsessions. Obsessions are ego-dystonic (the person recognizes them as irrational but cannot stop them). The pathophysiology involves dysfunction in the cortico-striato-thalamo-cortical (CSTC) circuit: the orbitofrontal cortex (error detection, feeling something is wrong) sends excessive signals through the caudate nucleus and thalamus, creating a loop of persistent anxiety and urge to perform compulsive behaviors. Serotonin system dysfunction is central (explaining why SSRIs are effective, but at HIGHER doses than for depression). Glutamate dysfunction also plays a role (explaining why glutamate-modulating agents like memantine and N-acetylcysteine show benefit in treatment-resistant OCD). Common obsession themes: contamination (most common), symmetry/ordering, forbidden/taboo thoughts (aggressive, sexual, religious), and harm (fear of accidentally causing harm). Common compulsions: washing/cleaning, checking, counting, repeating, ordering/arranging, and mental rituals (praying, reviewing). The practical nurse recognizes OCD symptoms, avoids inadvertently accommodating compulsions, and supports exposure and response prevention therapy.