|Classification and external resources|
An intrusive thought is an unwelcome involuntary thought, image, or unpleasant idea that may become an obsession, is upsetting or distressing, and can feel difficult to manage or eliminate. When such thoughts are associated with obsessive-compulsive disorder (OCD), depression, body dysmorphic disorder (BDD), and sometimes attention-deficit hyperactivity disorder (ADHD), the thoughts may become paralyzing, anxiety-provoking, or persistent. Intrusive thoughts may also be associated with episodic memory, unwanted worries or memories from OCD, posttraumatic stress disorder, other anxiety disorders, eating disorders, or psychosis. Intrusive thoughts, urges, and images are of inappropriate things at inappropriate times, and generally have aggressive, sexual, or blasphemous themes.
- 1 Description
- 2 Associated conditions
- 3 Treatment
- 4 Epidemiology
- 5 Notes
- 6 References
- 7 Further reading
- 8 External links
Many people experience the type of bad or unwanted thoughts that people with more troubling intrusive thoughts have, but most people can dismiss these thoughts. For most people, intrusive thoughts are a "fleeting annoyance." Psychologist Stanley Rachman presented a questionnaire to healthy college students and found that virtually all said they had these thoughts from time to time, including thoughts of sexual violence, sexual punishment, "unnatural" sex acts, painful sexual practices, blasphemous or obscene images, thoughts of harming elderly people or someone close to them, violence against animals or towards children, and impulsive or abusive outbursts or utterances. Such bad thoughts are universal among humans, and have "almost certainly always been a part of the human condition".
When intrusive thoughts occur with obsessive-compulsive disorder (OCD), patients are less able to ignore the unpleasant thoughts and may pay undue attention to them, causing the thoughts to become more frequent and distressing. The thoughts may become obsessions which are paralyzing, severe, and constantly present, and can range from thoughts of violence or sex to religious blasphemy. Distinguishing them from normal intrusive thoughts experienced by many people, the intrusive thoughts associated with OCD may be anxiety provoking, irrepressible, and persistent.
How people react to intrusive thoughts may determine whether these thoughts will become severe, turn into obsessions, or require treatment. Intrusive thoughts can occur with or without compulsions. Carrying out the compulsion reduces the anxiety, but makes the urge to perform the compulsion stronger each time it recurs, reinforcing the intrusive thoughts. According to Lee Baer, suppressing the thoughts only makes them stronger, and recognizing that bad thoughts do not signify that one is truly evil is one of the steps to overcoming them. There is evidence of the benefit of acceptance as an alternative to suppression of intrusive thoughts. A study showed that those instructed to suppress intrusive thoughts experienced more distress after suppression, while patients instructed to accept the bad thoughts experienced decreased discomfort. These results may be related to underlying cognitive processes involved in OCD. However, accepting the thoughts can be more difficult for persons with OCD. In the 19th century, OCD was known as "the doubting sickness"; the "pathological doubt" that accompanies OCD can make it harder for a person with OCD to distinguish "normal" intrusive thoughts as experienced by most people, causing them to "suffer in silence, feeling too embarrassed or worried that they will be thought crazy".
The possibility that most patients suffering from intrusive thoughts will ever act on those thoughts is low. Patients who are experiencing intense guilt, anxiety, shame, and upset over these thoughts are different from those who actually act on them. The history of violent crime is dominated by those who feel no guilt or remorse; the very fact that someone is tormented by intrusive thoughts and has never acted on them before is an excellent predictor that they will not act upon the thoughts. 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. According to Lee Baer, a patient should be concerned that intrusive thoughts are dangerous if the person does not feel upset by the thoughts, or rather finds them pleasurable; has ever acted on violent or sexual thoughts or urges; hears voices or sees things that others do not see; or feels uncontrollable irresistible anger.
Intrusive thoughts may involve violent obsessions about hurting others or themselves. They can be related to primarily obsessional obsessive compulsive disorder. These thoughts can include harming an innocent child; jumping from a bridge, mountain, or the top of a tall building; urges to jump in front of a train or automobile; and urges to push another in front of a train or automobile. Rachman's survey of healthy college students found that virtually all of them had intrusive thoughts from time to time, including:
- causing harm to elderly people
- imagining or wishing harm upon someone close to oneself
- impulses to violently attack, hit, harm or kill a person, small child, or animal
- impulses to shout at or abuse someone, or attack and violently punish someone, or say something rude, inappropriate, nasty, or violent to someone.
These thoughts are part of being human, and need not ruin quality of life. Treatment is available when the thoughts are associated with OCD and become persistent, severe, or distressing.
Sexual obsessions involve 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.
Like other unwanted intrusive thoughts or images, everyone has some inappropriate sexual thoughts at times, but people with OCD may attach significance to the unwanted sexual thoughts, generating anxiety and distress. The doubt that accompanies OCD leads to uncertainty regarding whether one might act on the intrusive thoughts, resulting in self-criticism or loathing.
One of the more common sexual intrusive thoughts occurs when an obsessive person doubts his or her sexual identity. As in the case of most sexual obsessions, sufferers may feel shame and live in isolation, finding it hard to discuss their fears, doubts, and concerns about their sexual identity.
A person experiencing sexual intrusive thoughts may feel shame, "embarrassment, guilt, distress, torment, fear of acting on the thought or perceived impulse, and doubt about whether they have already acted in such a way." Depression may be a result of the self-loathing that can occur, depending on how much the OCD interferes with daily functioning or causes distress. Their concern over these thoughts may cause them to scrutinize their bodies to determine if the thoughts result in feelings of arousal. However, focusing attention of any part of the body can result in feelings in that part of the body, hence doing so may decrease confidence and increase fear about acting on the urges. Part of treatment of sexual intrusive thoughts involves therapy to help sufferers accept intrusive thoughts and stop trying to reassure themselves by checking their bodies.
Blasphemous thoughts are a common component of OCD, documented throughout history; notable religious figures such as Martin Luther and Ignatius of Loyola were known to be tormented by intrusive, blasphemous or religious thoughts and urges. Martin Luther had urges to curse God and Jesus, and was obsessed with images of "the Devil's behind". St. Ignatius had numerous obsessions, including the fear of stepping on pieces of straw forming a cross, fearing that it showed disrespect to Christ. A study of 50 patients with a primary diagnosis of obsessive-compulsive disorder found that 40% had religious and blasphemous thoughts and doubts—a higher, but not statistically significantly different number than the 38% who had the obsessional thoughts related to dirt and contamination more commonly associated with OCD. One study suggests that content of intrusive thoughts may vary depending on culture, and that blasphemous thoughts may be more common in men than in women.
According to Fred Penzel, a New York psychologist, some common religious obsessions and intrusive thoughts are:
- sexual thoughts about God, saints, and religious figures
- bad thoughts or images during prayer or meditation
- thoughts of being possessed
- fears of sinning or breaking a religious law or performing a ritual incorrectly
- fears of omitting prayers or reciting them incorrectly
- repetitive and intrusive blasphemous thoughts
- urges or impulses to say blasphemous words or commit blasphemous acts during religious services.
Suffering can be greater and treatment complicated when intrusive thoughts involve religious implications; patients may believe the thoughts are inspired by Satan, and may fear punishment from God or have magnified shame because they perceive themselves as sinful. Symptoms can be more distressing for sufferers with strong religious convictions or beliefs.
Baer believes that blasphemous thoughts are more common in Catholics and evangelical Protestants than in other religions, whereas Jews or Muslims tend to have obsessions related more to complying with the laws and rituals of their faith, and performing the rituals perfectly. He hypothesizes that this is because what is considered inappropriate varies among cultures and religions, and intrusive thoughts torment their sufferers with whatever is considered most inappropriate in the surrounding culture.
Intrusive thoughts are associated with OCD or obsessive-compulsive personality disorder, but may also occur with other conditions such as post-traumatic stress disorder, clinical depression, postpartum depression, and anxiety. One of these conditions is almost always present in people whose intrusive thoughts reach a clinical level of severity. A large study published in 2005 found that aggressive, sexual, and religious obsessions were broadly associated with comorbid anxiety disorders and depression. The intrusive thoughts that occur in a schizophrenic episode differ from the obsessional thoughts that occur with OCD or depression in that the intrusive thoughts of schizophrenics are false or delusional beliefs (i.e. held by the schizophrenic individual to be real and not doubted, as is typically the case with intrusive thoughts) .
Post-traumatic stress disorder
The key difference between OCD and post-traumatic stress disorder (PTSD) is that the intrusive thoughts of PTSD sufferers are of traumatic events that actually happened to them, whereas OCD sufferers have thoughts of imagined catastrophes. PTSD patients with intrusive thoughts have to sort out violent, sexual, or blasphemous thoughts from memories of traumatic experiences. When patients with intrusive thoughts do not respond to treatment, physicians may suspect past physical, emotional, or sexual abuse.
People who are clinically depressed may experience intrusive thoughts more intensely, and view them as evidence that they are worthless or sinful people. The suicidal thoughts that are common in depression must be distinguished from intrusive thoughts, because suicidal thoughts—unlike harmless sexual, aggressive, or religious thoughts—can be dangerous.
Postpartum depression and OCD
Unwanted thoughts by mothers about harming infants are common in postpartum depression. A 1999 study of 65 women with postpartum major depression by Katherine Wisner et al. found the most frequent aggressive thought for women with postpartum depression was causing harm to their newborn infants. 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.
Some women may develop symptoms of OCD during pregnancy or the postpartum period. Postpartum OCD occurs mainly in women who may already have OCD, perhaps in a mild or undiagnosed form. Postpartum depression and OCD may be comorbid (often occurring together). And though physicians may focus more on the depressive symptoms, one study found that obsessive thoughts did accompany postpartum depression in 57% of new mothers.
Wisner found common obsessions about harming babies in mothers experiencing postpartum depression include images of the baby lying dead in a casket or being eaten by sharks; stabbing the baby; throwing the baby down the stairs; or drowning or burning the baby (as by submerging it in the bathtub in the former case or throwing it in the fire or putting it in the microwave in the latter). Baer estimates that up to 200,000 new mothers with postpartum depression each year may develop these obsessional thoughts about their babies; and because they may be reluctant to share these thoughts with a physician or family member, or suffer in silence and fear they are "crazy", their depression can worsen.
Intrusive fears of harming immediate children can last longer than the postpartum period. 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. Among non-depressed mothers, the study found 7% had thoughts of harming their child—a rate that yields an additional 280,000 non-depressed mothers in the United States with intrusive thoughts about harming their children.
Treatment for intrusive thoughts is similar to treatment for OCD. Exposure and response prevention therapy—also referred to as habituation or desensitization—is useful in treating intrusive thoughts. Mild cases can also be treated with cognitive behavioral therapy, which helps patients identify and manage the unwanted thoughts.
Exposure therapy is the treatment of choice for intrusive thoughts. According to Deborah Osgood-Hynes, Psy.D. Director of Psychological Services and Training at the MGH/McLean OCD Institute, "In order to reduce a fear, you have to face a fear. This is true of all types of anxiety and fear reactions, not just OCD."
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. By engaging in a ritual or compulsion to diminish the anxiety or bad feeling, the action is strengthened via a process called negative reinforcement—the mind learns that the way to avoid the bad feeling is by engaging in a ritual or compulsions. When OCD becomes severe, this leads to more interference in life and continues the frequency and severity of the thoughts the person sought to avoid.
Exposure therapy (or exposure and response prevention) is the practice of staying in an anxiety-provoking or feared situation until the distress or anxiety diminishes. The goal is to reduce the fear reaction, learning to not react to the bad thoughts. This is the most effective way to reduce the frequency and severity of the intrusive thoughts. 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." Exposure therapy will not completely eliminate intrusive thoughts—everyone has bad thoughts—but most patients find that it can decrease their thoughts sufficiently that intrusive thoughts no longer interfere with their lives.
Cognitive behavioral therapy
Cognitive behavioral therapy (CBT) is a newer therapy than exposure therapy, available for those unable or unwilling to undergo exposure therapy. Cognitive therapy has been shown to be useful in reducing intrusive thoughts, but developing a conceptualization of the obsessions and compulsions with the patient is important.
Antidepressants or antipsychotic medications may be used for more severe cases if intrusive thoughts do not respond to cognitive behavioral or exposure therapy alone. 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. Intrusive thoughts may occur in persons with Tourette syndrome (TS) who also have OCD; the obsessions in TS-related OCD are thought to respond to SSRI drugs as well.
Antidepressants which have been shown to be effective in treating OCD include fluvoxamine (trade name Luvox), fluoxetine (Prozac), sertraline (Zoloft), paroxetine (Paxil), citalopram (Celexa), and clomipramine (Anafranil). Although SSRIs are known to be effective for OCD in general, there have been fewer studies on their effectiveness for intrusive thoughts. A retrospective chart review of patients with sexual symptoms treated with SSRIs showed the greatest improvement was in those with intrusive sexual obsessions typical of OCD. A study of ten patients with religious or blasphemous obsessions found that most patients responded to treatment with fluoxetine or clomipramine. 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.
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).
A 2007 study found that 78% of a clinical sample of OCD patients had intrusive images. Most people who suffer from intrusive thoughts have not identified themselves as having OCD, because they may not have what they believe to be classic symptoms of OCD, such as handwashing. Yet, epidemiological studies suggest that intrusive thoughts are the most common kind of OCD worldwide; if people in the United States with intrusive thoughts gathered, they would form the fourth-largest city in the US, following New York City, Los Angeles, and Chicago.
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 sufferers in the United States alone (as of 2000). One author estimates that one in 50 adults have OCD and about 10–20% of these have sexual obsessions. A recent study found that 25% of 293 patients with a primary diagnosis of OCD had a history of sexual obsessions.
- "Intrusive thoughts". OCD Action. Archived from the original on September 28, 2007. Retrieved December 27, 2010.
- Baer (2001), pp. 58–60
- Brewin CR, Gregory JD, Lipton M, Burgess N (January 2010). "Intrusive images in psychological disorders: characteristics, neural mechanisms, and treatment implications". Psychol Rev. 117 (1): 210–32. doi:10.1037/a0018113. PMC . PMID 20063969.
- Baer (2001), p. xiv.
- Baer (2001), p. 5
- As reported in Baer (2001), p. 7: Rachman S, de Silva P (1978). "Abnormal and normal obsessions". Behav Res Ther. 16 (4): 233–48. doi:10.1016/0005-7967(78)90022-0. PMID 718588.
- Baer (2001), p. 8
- Colino, Stacey. "Scary Thoughts: It's Normal for New Parents to Worry Their Baby May Face Harm. For Some Women, Though, Such Fears Become Overwhelming". The Washington Post (March 7, 2006). Retrieved on December 30, 2006.
- Baer (2001), p. 17
- Marcks BA, Woods DW (April 2005). "A comparison of thought suppression to an acceptance-based technique in the management of personal intrusive thoughts: a controlled evaluation". Behav Res Ther. 43 (4): 433–45. doi:10.1016/j.brat.2004.03.005. PMID 15701355.
- Tolin DF, Abramowitz JS, Przeworski A, Foa EB (November 2002). "Thought suppression in obsessive-compulsive disorder". Behav Res Ther. 40 (11): 1255–74. doi:10.1016/S0005-7967(01)00095-X. PMID 12384322.
- Penzel, Fred. "How Do I Know I'm Not Really Gay?" Retrieved on January 1, 2007
- Penzel, Fred. "Let He Who Is Without Sin": OCD and Religion. Retrieved on January 1, 2007
- Baer (2001), pp. 37–38
- Baer (2001), pp. 43–44
- Baer (2001), pp. 33, 78
- Baer (2001), p. xv
- Osgood-Hynes, Deborah. "Thinking Bad Thoughts" (PDF). MGH/McLean OCD Institute, Belmont, MA. OCD Foundation, Milford, CT. Archived from the original (PDF) on June 25, 2008. Retrieved December 27, 2010.
- Baer (2001), p. 35
- Baer (2001), p.106
- Erickson, Erik H. Young Man Luther: A Study in Psychoanalysis and History. New York: W.W. Norton, 1962
- Ciarrocchi, Joseph W. "Religion, Scrupulosity, and Obsessive-Compulsive Disorder," in Michael A. Jenike, Lee Baer, and William A. MInichiello, eds., Obsessive-Compulsive Disorders: Practical Management, 3rd ed. St. Louis: Mosby, 1998
- Shooka A, al-Haddad MK, Raees A (1998). "OCD in Bahrain: a phenomenological profile". Int J Soc Psychiatry. 44 (2): 147–54. doi:10.1177/002076409804400207. PMID 9675634.
- Ghassemzadeh H, Mojtabai R, Khamseh A, Ebrahimkhani N, Issazadegan AA, Saif-Nobakht Z (March 2002). "Symptoms of obsessive-compulsive disorder in a sample of Iranian patients". Int J Soc Psychiatry. 48 (1): 20–8. doi:10.1177/002076402128783055. PMID 12008904.
- Baer (2001), p. 108
- Baer (2001), p. 109
- Baer (2001), pp. 111–112
- Baer (2001), p. 112
- Baer (2001), p. 40, 57
- Michael T, Halligan SL, Clark DM, Ehlers A (2007). "Rumination in posttraumatic stress disorder". Depress Anxiety. 24 (5): 307–17. doi:10.1002/da.20228. PMID 17041914.
- Christopher G, MacDonald J (November 2005). "The impact of clinical depression on working memory". Cogn Neuropsychiatry. 10 (5): 379–99. doi:10.1080/13546800444000128. PMID 16571468.
- Antoni MH, Wimberly SR, Lechner SC, et al. (October 2006). "Reduction of cancer-specific thought intrusions and anxiety symptoms with a stress management intervention among women undergoing treatment for breast cancer". Am J Psychiatry. 163 (10): 1791–7. doi:10.1176/appi.ajp.163.10.1791. PMID 17012691.
- Compas BE, Beckjord E, Agocha B, et al. (December 2006). "Measurement of coping and stress responses in women with breast cancer". Psychooncology. 15 (12): 1038–54. doi:10.1002/pon.999. PMID 17009343.
- Baer also mentions Tourette syndrome (TS), but notes that it is the combination of comorbid OCD—when present—and tics that accounts for the intrusive, obsessive thoughts. People with tic-related OCD (OCD plus tics) are more likely to have violent or sexual obsessions. Leckman JF, Grice DE, Barr LC, et al. (1994). "Tic-related vs. non-tic-related obsessive compulsive disorder". Anxiety. 1 (5): 208–15. PMID 9160576.
- Baer (2001), p. 51
- Hasler G, LaSalle-Ricci VH, Ronquillo JG, et al. (June 2005). "Obsessive-compulsive disorder symptom dimensions show specific relationships to psychiatric comorbidity". Psychiatry Res. 135 (2): 121–32. doi:10.1016/j.psychres.2005.03.003. PMID 15893825.
- Waters FA, Badcock JC, Michie PT, Maybery MT (January 2006). "Auditory hallucinations in schizophrenia: intrusive thoughts and forgotten memories". Cogn Neuropsychiatry. 11 (1): 65–83. doi:10.1080/13546800444000191. PMID 16537234.
- Baer (2001), pp. 62–64
- Baer (2001), p. 67
- Baer (2001), pp. 51–53
- Baer (2001), p. 20
- As reported in Baer (2001), pp. 20–23, 139–40: Wisner KL, Peindl KS, Gigliotti T, Hanusa BH (March 1999). "Obsessions and compulsions in women with postpartum depression". J Clin Psychiatry. 60 (3): 176–80. doi:10.4088/JCP.v60n0305. PMID 10192593.
- Abramowitz JS, Khandker M, Nelson CA, Deacon BJ, Rygwall R (September 2006). "The role of cognitive factors in the pathogenesis of obsessive-compulsive symptoms: a prospective study". Behav Res Ther. 44 (9): 1361–74. doi:10.1016/j.brat.2005.09.011. PMID 16352291.
- Arnold LM (August 1999). "A Case Series of Women With Postpartum-Onset Obsessive-Compulsive Disorder". Prim Care Companion J Clin Psychiatry. 1 (4): 103–108. doi:10.4088/PCC.v01n0402. PMC . PMID 15014682.
- Baer (2001), p. 21
- Baer (2001), p. 22
- Baer (2001), p. 23
- As reported in Baer (2001), p. 51: Jennings KD, Ross S, Popper S, Elmore M (July 1999). "Thoughts of harming infants in depressed and nondepressed mothers". J Affect Disord. 54 (1–2): 21–8. doi:10.1016/S0165-0327(98)00185-2. PMID 10403143.
- Baer (2001), p. 24
- Baer (2001), p. 91
- Baer (2001), p. 73
- Baer (2001), p. 86
- Deblinger E, Stauffer LB, Steer RA (November 2001). "Comparative efficacies of supportive and cognitive behavioral group therapies for young children who have been sexually abused and their nonoffending mothers". Child Maltreat. 6 (4): 332–43. doi:10.1177/1077559501006004006. PMID 11675816.
- Sousa MB, Isolan LR, Oliveira RR, Manfro GG, Cordioli AV (July 2006). "A randomized clinical trial of cognitive-behavioral group therapy and sertraline in the treatment of obsessive-compulsive disorder". J Clin Psychiatry. 67 (7): 1133–9. doi:10.4088/JCP.v67n0717. PMID 16889458.
- Purdon C (November 2004). "Cognitive-behavioral treatment of repugnant obsessions". J Clin Psychol. 60 (11): 1169–80. doi:10.1002/jclp.20081. PMID 15389619.
- Baer (2001), pp. 113–114
- Baer (2001), p. 144
- Medication trade names may differ between countries. In general, this article uses North American trade names.
- Baer (2001), p. 116
- Baer (2001), p. 115
- As reported in Baer (2001), p. 115: Stein DJ, Hollander E, Anthony DT, et al. (August 1992). "Serotonergic medications for sexual obsessions, sexual addictions, and paraphilias". J Clin Psychiatry. 53 (8): 267–71. PMID 1386848.
- As reported in Baer (2001), p. 115: Fallon BA, Liebowitz MR, Hollander E, et al. (December 1990). "The pharmacotherapy of moral or religious scrupulosity". J Clin Psychiatry. 51 (12): 517–21. PMID 2258366.
- Baer (2001), p. 120
- Baer (2001), p. 119
- Albert U, Bergesio C, Pessina E, Maina G, Bogetto F (June 2002). "Management of treatment resistant obsessive-compulsive disorder. Algorithms for pharmacotherapy". Panminerva Med. 44 (2): 83–91. PMID 12032425.
- Palatnik A, Frolov K, Fux M, Benjamin J (June 2001). "Double-blind, controlled, crossover trial of inositol versus fluvoxamine for the treatment of panic disorder". J Clin Psychopharmacol. 21 (3): 335–9. doi:10.1097/00004714-200106000-00014. PMID 11386498.
* Levine J (May 1997). "Controlled trials of inositol in psychiatry". Eur Neuropsychopharmacol. 7 (2): 147–55. doi:10.1016/S0924-977X(97)00409-4. PMID 9169302.
- Baer (2001), p. xvii
- Baer (2001), pp. 36–37
- Grant JE, Pinto A, Gunnip M, Mancebo MC, Eisen JL, Rasmussen SA (2006). "Sexual obsessions and clinical correlates in adults with obsessive-compulsive disorder". Compr Psychiatry. 47 (5): 325–9. doi:10.1016/j.comppsych.2006.01.007. PMID 16905392.
- Baer, Lee (2001). The Imp of the Mind: Exploring the Silent Epidemic of Obsessive Bad Thoughts. New York: Dutton. ISBN 0-525-94562-8.
- Abramowitz JS, Schwartz SA, Moore KM, Luenzmann KR (2003). "Obsessive-compulsive symptoms in pregnancy and the puerperium: a review of the literature". J Anxiety Disord. 17 (4): 461–78. doi:10.1016/s0887-6185(02)00206-2. PMID 12826092.
- Julien D, O'Connor KP, Aardema F (April 2007). "Intrusive thoughts, obsessions, and appraisals in obsessive-compulsive disorder: a critical review". Clin Psychol Rev. 27 (3): 366–83. doi:10.1016/j.cpr.2006.12.004. PMID 17240502.
- Marsh R, Maia TV, Peterson BS (June 2009). "Functional disturbances within frontostriatal circuits across multiple childhood psychopathologies". Am J Psychiatry. 166 (6): 664–74. doi:10.1176/appi.ajp.2009.08091354. PMC . PMID 19448188.
- Rachman S (December 2007). "Unwanted intrusive images in obsessive compulsive disorders". J Behav Ther Exp Psychiatry. 38 (4): 402–10. doi:10.1016/j.jbtep.2007.10.008. PMID 18054779.
- Yorulmaz O, Gençöz T, Woody S (April 2009). "OCD cognitions and symptoms in different religious contexts". J Anxiety Disord. 23 (3): 401–6. doi:10.1016/j.janxdis.2008.11.001. PMID 19108983.
- Book Forum: Compulsive Disorders – The Imp of the Mind: Exploring the Silent Epidemic of Obsessive Bad Thoughts. Book review from The American Journal of Psychiatry, 159:1952–1953, November 2002
- Packer, Leslie. OCD Overview