Describe the brain circuit that is implicated in OCD. Identify several disorders that are related to OCD in terms of symptoms and/or brain areas affected.

Question

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Answer 1

OCD patients show increased activity in the orbitofrontal cortex and a part of the basal ganglia called the caudate nucleus. Disruption in communication among brain structures is also evident due to reductions in white matter. This effect is observed between the cingulate gyrus and a circuit of brain structures involved in impulse control (the basal ganglia, thalamus, and cortex).
A disorder of excessive grooming called acral lick syndrome is symptomatically similar to the excessive ritual portrayed by OCD patients, such as excessive hand washing. Other behaviors observed in animals that are similar include excessive self-grooming and hair pulling in monkeys and compulsive feather pulling in some birds in captivity. In humans, similar behaviors include trichotillomania. This excessive hair pulling in humans shows similarities with OCD, including being hereditary. Hair pullers also show a high frequency of relatives with OCD. Both respond to drug treatment that increases serotonin, although their causes may be due to a different version of the same gene.
OCD patients are more likely to also be hoarders. However, the two are separate disorders, with different brain areas activated.
Similarities between OCD and Tourette syndrome include the ability to manage symptoms for a short period of time; sharing of some genetic roots (1/3 of OCD patients also have Tourette's; 30% of Tourette's patients also have OCD). Both disorders also involve increased activity in the basal ganglia. However, drug treatment is different between the two.