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Obsessive compulsive disorders

Obsessive-Compulsive Disorder (OCD) is a prevalent and debilitating mental disorder, affecting 1-3% of individuals across the world at some point during their lives1.

OCD is characterised by hallmark symptoms of obsessions (recurrent intrusive thoughts that enter into the stream of consciousness, which tend to be unpleasant and distressing), and/or compulsions (repetitive mental or physical acts that are driven by obsessions or undertaken in a rigid way)2.

For a formal diagnosis of OCD, symptoms must be distressing, time-consuming, or functionally impairing. OCD onset shows peaks in childhood (mean age 10 years) and young adulthood (mean age 21 years), and often persists over time, being equally common in men and women. The World Health Organization has highlighted OCD as a global leading cause of non-fatal illness3.

In the Diagnostic and Statistical Manual Version 5 (DSM-5), OCD is included in a category of ‘Obsessive-Compulsive and Related Disorders’, which also includes hoarding disorder, hair pulling disorder, skin picking disorder, and body dysmorphic disorder.

Left untreated, OCD and related disorders can have a profound negative effect on quality of life for sufferers and their families. In a review of 155 data articles, OCD was associated with significant functional disability, and worse symptom severity than several other mental disorders4.

OCD and other obsessive-compulsive conditions are burdensome for society at large – the estimated economic impact of OCD was $8.4 billion per year in 1990, in terms of direct and indirect costs6.


Pathology and functional impact of Obsessive-Compulsive Disorder

As with most psychiatric disorders, the brain basis of OCD and related disorders is not yet fully understood. Genetic factors have been implicated, with OCD having a heritability of up to 50%7. Genes implicated in OCD are involved in regulating the serotonin and other neurochemical transmitter pathways.

There is considerable evidence that OCD is associated with structural and functional abnormalities of brain circuits responsible for generating ‘habits’, and responsible for exerting top-down flexible control over such thoughts and behaviours8.

Compared to controls, OCD patients show abnormal structural connections between brain regions including the orbitofrontal and anterior cingulate cortices, responsible for error detection and response suppression9.

Patients with OCD also show relative reductions in frontal cortex grey matter coupled with excess grey matter in the basal ganglia10,11. In view of the brain circuitry implicated in OCD, it is to be expected that patients would experience difficulties in cognitive domains dependent on these neural regions.

Deficits are commonly reported on tests of response inhibition, flexible responding / attentional flexibility, working memory, and associative learning12,13.


Research and development in Obsessive-Compulsive Disorder

Multiple evidence-based treatment options exist for OCD. The precise choice of treatments at an individual level should be determined following assessment by a healthcare professional, taking into consideration relevant guidelines.

Treatments including the tricyclic medication clomipramine, and selective serotonin reuptake inhibitors, show efficacy compared to placebo in treating OCD according to meta-analysis14.

Similar positive results have been found in meta-analysis for psychotherapy (especially cognitive behavioural therapy) compared to waiting-list control conditions15.

For treatment-resistant OCD, augmentation of serotonin reuptake inhibitor with low-dose antipsychotic medication (e.g. risperidone, aripiprazole) has shown benefit in some trials, compared to serotonin reuptake inhibitor alone16.

In addition to considering OCD, it is important for healthcare professionals to screen for other mental disorders and to treat comorbidities as well.

Mood and anxiety disorders are common in OCD, and the healthcare professional should also screen for the other obsessive-compulsive related disorders, such as body dysmorphic disorder or hoarding disorder.

While treatments are available for OCD and related disorders, up to 60% of people do not achieve satisfactory clinical improvement with first-line treatments, or are unable to tolerate these treatments. Furthermore, many of the hallmark cognitive problems in OCD especially response inhibition deficits and memory problems commonly persist despite first-line treatments.

The search is on for treatments for that can fully ameliorate cognitive impairment in OCD, in order to maximise long-term outcomes and quality of life.


You might also be interested in…

Veale D, et al. Atypical antipsychotic augmentation in SSRI treatment refractory obsessive-compulsive disorder: a systematic review and meta-analysis. BMC Psychiatry. 2014 Nov 29;14:317.

Morein-Zamir S, et al. Impaired visuospatial associative memory and attention in obsessive compulsive disorder but no evidence for differential dopaminergic modulation. Psychopharmacology (Berl). 2010 Oct;212(3):357-67. doi: 10.1007/s00213-010-1963-z. Epub 2010 Jul 27.

Chamberlain SR, et al. Impaired cognitive flexibility and motor inhibition in unaffected first-degree relatives of patients with obsessive-compulsive disorder. Am J Psychiatry. 2007 Feb;164(2):335-8.


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  2. American Psychiatric Association (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Washington, DC.
  3. Ayuso-Mateos J. Global burden of obsessive-compulsive disorder in the year 2000. Geneva: World Health Organization, 2006.
  4. Koran LM. Quality of life in obsessive-compulsive disorder. Psychiatr Clin North Am. 2000 Sep;23(3):509-17.
  5. Subramaniam M, Soh P, Ong C, Esmond Seow LS, Picco L, Vaingankar JA, Chong SA. Patient-reported outcomes in obsessive-compulsive disorder. Dialogues Clin Neurosci. 2014 Jun;16(2):239-54.
  6. DuPont RL, Rice DP, Shiraki S, Rowland CR. Economic costs of obsessive-compulsive disorder. Med Interface. 1995 Apr;8(4):102-9.
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  8. van den Heuvel OA, van Wingen G, Soriano-Mas C, Alonso P, Chamberlain SR, Nakamae T, Denys D, Goudriaan AE, Veltman DJ. Brain circuitry of compulsivity. Eur Neuropsychopharmacol. 2016 May;26(5):810-27.
  9. Piras F, Piras F, Caltagirone C, Spalletta G. Brain circuitries of obsessive compulsive disorder: a systematic review and meta-analysis of diffusion tensor imaging studies. Neurosci Biobehav Rev. 2013 Dec;37(10 Pt 2):2856-77.
  10. Rotge JY, Langbour N, Guehl D, Bioulac B, Jaafari N, Allard M, Aouizerate B, Burbaud P. Gray matter alterations in obsessive-compulsive disorder: an anatomic likelihood estimation meta-analysis. Neuropsychopharmacology. 2010 Feb;35(3):686-91. doi: 10.1038/npp.2009.175. Epub 2009 Nov 4.
  11. Chamberlain SR, Menzies L. Endophenotypes of obsessive-compulsive disorder: rationale, evidence and future potential. Expert Rev Neurother. 2009 Aug;9(8):1133-46.
  12. Chamberlain SR, Blackwell AD, Fineberg NA, Robbins TW, Sahakian BJ. The neuropsychology of obsessive compulsive disorder: the importance of failures in cognitive and behavioural inhibition as candidate endophenotypic markers. Neurosci Biobehav Rev. 2005 May;29(3):399-419.
  13. Shin NY, Lee TY, Kim E, Kwon JS. Cognitive functioning in obsessive-compulsive disorder: a meta-analysis. Psychol Med. 2014 Apr;44(6):1121-30.
  14. Fineberg NA, Gale TM. Evidence-based pharmacotherapy of obsessive-compulsive disorder. Int J Neuropsychopharmacol. 2005 Mar;8(1):107-29.
  15. Öst LG, Havnen A, Hansen B, Kvale G. Cognitive behavioral treatments of obsessive-compulsive disorder. A systematic review and meta-analysis of studies published 1993-2014. Clin Psychol Rev. 2015 Aug;40:156-69.
  16. Veale D, Miles S, Smallcombe N, Ghezai H, Goldacre B, Hodsoll J. Atypical antipsychotic augmentation in SSRI treatment refractory obsessive-compulsive disorder: a systematic review and meta-analysis. BMC Psychiatry. 2014 Nov 29;14:317.