[11] The thoughts may become obsessions that are paralyzing, severe, and constantly present, and they may involve topics such as violence, sex, or blasphemy.

Patients who are not troubled or shamed by their thoughts, do not find them distasteful, or who have actually taken action, might need to have more serious conditions such as psychosis or potentially criminal behaviors ruled out.

[20] The phenomenon is more commonly experienced by individuals with a high level of anxiety sensitivity, and may be caused by the conscious mind's misinterpretation of an instinctive safety signal.

[1][20] Sexual obsession involves intrusive thoughts or images of "kissing, touching, fondling, oral sex, anal sex, intercourse, and rape" with "strangers, acquaintances, parents, children, family members, friends, coworkers, animals, and religious figures," involving "heterosexual or homosexual content" with persons of any age.

The doubt that accompanies OCD leads to uncertainty regarding whether one might act on the intrusive thoughts, resulting in self-criticism or loathing.

Individuals in this age range tend to be less experienced at coping with these thoughts, and the stress and negative effect induced by them.

Younger adults also tend to have stressors specific to that period of life that can be particularly challenging especially in the face of intrusive thoughts.

[38] Those in middle adulthood (40-60) have the highest prevalence of OCD and therefore seem to be the most susceptible to the anxiety and negative emotions associated with intrusive thought.

[47] A large study published in 2005 found that aggressive, sexual, and religious obsessions were broadly associated with comorbid anxiety disorders and depression.

[49] When patients with intrusive thoughts do not respond to treatment, physicians may suspect past physical, emotional, or sexual abuse.

[50] If a person who has experienced trauma practices looks for the positive outcomes, it is suggested they will experience less depression and higher self well-being.

[53] Non-depressed individuals have been shown to have a higher activation in the dorsolateral prefrontal cortex while attempting to suppress intrusive thoughts.

The dorsolateral prefrontal cortex is the area of the brain that primarily functions in cognition, working memory, and planning.

When the intrusive thoughts re-emerge, non-depressed individuals also show higher activation levels in the anterior cingulate cortices, which functions in error detection, motivation, and emotional regulation, than their depressed counterparts.

[54] Roughly 60% of depressed individuals report experiencing bodily, visual, or auditory perceptions along with their intrusive thoughts.

[57] A study of 85 new parents found that 89% experienced intrusive images, for example, of the baby suffocating, having an accident, being harmed, or being kidnapped.

A study of 100 clinically depressed women found that 41% had obsessive fears that they might harm their child, and some were afraid to care for their children.

[21] Mild cases can also be treated with cognitive behavioral therapy, which helps patients identify and manage the unwanted thoughts.

Because it is uncomfortable to experience bad thoughts and urges, shame, doubt or fear, the initial reaction is usually to do something to make the feelings diminish.

[21] The goal is to be able to "expose yourself to the thing that most triggers your fear or discomfort for one to two hours at a time, without leaving the situation, or doing anything else to distract or comfort you.

[65] Cognitive therapy has been shown to be useful in reducing intrusive thoughts,[68][69] but developing a conceptualization of the obsessions and compulsions with the patient is important.

"[71] Antidepressants or antipsychotic medications may be used for more severe cases if intrusive thoughts do not respond to cognitive behavioral or exposure therapy alone.

[12][72] Whether the cause of intrusive thoughts is OCD, depression, or post-traumatic stress disorder, the selective serotonin reuptake inhibitor (SSRI) drugs (a class of antidepressants) are the most commonly prescribed.

[73] Antidepressants that have been shown to be effective in treating OCD include fluvoxamine (trade name[a] Luvox), fluoxetine (Prozac), sertraline (Zoloft), paroxetine (Paxil), citalopram (Celexa), and clomipramine (Anafranil).

[77] Women with postpartum depression often have anxiety as well, and may need lower starting doses of SSRIs; they may not respond fully to the medication, and may benefit from adding cognitive behavioral or response prevention therapy.

[78] Patients with intense intrusive thoughts that do not respond to SSRIs or other antidepressants may be prescribed typical and atypical neuroleptics including risperidone (trade name Risperdal), ziprasidone (Geodon), haloperidol (Haldol), and pimozide (Orap).

[82] The prevalence of OCD in every culture studied is at least 2% of the population, and the majority of those have obsessions, or bad thoughts, only; this results in a conservative estimate of more than 2 million affected individuals in the United States alone (as of 2000).