Whether or not behaviors are compulsions or mere habit depends on the context in which the behaviors are performed.
OCD without overt compulsions could, by one estimate, characterize as many as 50 percent to 60 percent of OCD cases.
Some people with OCD perform compulsive rituals because they inexplicably feel they have to, while others act compulsively so as to mitigate the anxiety that stems from particular obsessive thoughts.
Neuroimaging studies on this have been too few, and the subtypes examined have differed too much to draw any conclusions.
On the other hand, subtype dependent treatment response has been studied, and the hoarding subtype has consistently responded least to treatment.
Furthermore, some subtypes have been associated with improvement in performance on certain tasks such as pattern recognition (washing subtype) and spatial working memory (obsessive thought subtype).
Subgroups have also been distinguished by neuroimaging findings and treatment response.The "forbidden thoughts factor" correlated highly with intrusive and distressing thoughts of a violent, religious, or sexual nature.The "cleaning factor" correlated highly with obsessions about contamination and compulsions related to cleaning.The "hoarding factor" only involved hoarding-related obsessions and compulsions, and was identified as being distinct from other symptom groupings.While OCD has been considered a homogenous disorder from a neuropsychological perspective, many of the putative neuropsychological deficits may be due to comorbid disorders.In other words, habits tend to bring efficiency to one's life, while compulsions tend to disrupt it.In addition to the anxiety and fear that typically accompanies OCD, sufferers may spend hours performing such compulsions every day.A relatively vague obsession could involve a general sense of disarray or tension accompanied by a belief that life cannot proceed as normal while the imbalance remains.A more intense obsession could be a preoccupation with the thought or image of someone close to them dying Other obsessions concern the possibility that someone or something other than oneself—such as God, the devil, or disease—will harm either the person with OCD or the people or things that the person cares about.As with other intrusive, unpleasant thoughts or images, some disquieting sexual thoughts at times are normal, but people with OCD may attach extraordinary significance to the thoughts.For example, obsessive fears about sexual orientation can appear to the person with OCD, and even to those around them, as a crisis of sexual identity.