3.9.6 Obsessive-compulsive disorder and related conditions

Obsessive-Compulsive Disorder

Although the best description of compulsivity is likely to depend on perspective and context, compulsive disorders include obsessive-compulsive disorder (OCD) and related diseases such as hoarding disorder, body dysmorphic disorder, trichotillomania, skin picking disorder, and Tourette’s.

A range of overlapping diseases known as ‘obsessive-compulsive and related disorders’ described in the DSM-5 include OCD amongst a number of other conditions. Many of us occasionally have unpleasant ideas (such as yearning for double cheeseburgers when dieting) and frequently participate in repetitive activities (e.g., pacing when nervous). However, OCD and other similar diseases intensify unwanted thoughts and repetitive behaviours to the point that they interfere with daily life. OCD typically feature intrusive, unpleasant thoughts and repetitive activities.

Obsessions differ from regular fears we might have, such as legitimate worries about being fired from a job, and they are more severe. Obsessions are more than just unwelcome ideas that occasionally seem to jump into our heads arbitrarily. Instead, obsessions are defined as persistent desires and ideas that are unintentionally undesired, invasive, and distressing.

Compulsions are repetitive, ritualistic behaviours that are often practised to lessen the suffering that obsessions cause or to lessen the chance of a dreaded outcome. Compulsions frequently involve repetitive and thorough hand washing, cleaning, checking (like making sure a door is closed), and organising (like placing all the pencils in a specific order). They can also involve mental acts like counting, praying, or repeating aloud to oneself. OCD-specific compulsions are not pleasurable and are not realistically related to the cause of the suffering or the feared event. In the United States, 2.3% of people will develop OCD at some point in their lives (Brock, 2020).

Diagnosis:

Manual:	Summary:
ICD 11	Presence of persistent obsessions and/or compulsions. 1) Obsessions and compulsions are time-consuming (e.g., take more than 1 hour per day) or result in significant distress or significant impairment in personal, family, social, educational, occupational, or other important areas of functioning. If functioning is maintained, it is only through significant additional effort. 2) The symptoms or behaviours are not a manifestation of another medical condition (e.g., basal ganglia ischemic stroke) and are not due to the effects of a substance or medication on the central nervous system (e.g., amphetamine), including withdrawal effects.
DSM 5	1) Recurrent and persistent thoughts, urges or images that are experienced, at some time during the disturbance, as intrusive, unwanted, and that in most individuals cause marked anxiety or distress. 2) The thoughts, impulses, or images are not simply excessive worries about real-life problems.

Aetiology:

The exact cause of OCD is unknown, but likely multifactorial. OCD appears to be heritable with the heritability being as high as 45-65% in children and 27-45% in adults.

Monozygotic : Dizygotic = 50-80% : 25%.

35% of 1st-degree relatives will also suffer from OCD

Phenomenology:

Management:

Management modality:	Summary:
Psychological	Cognitive behavioural therapy: more effective than pharmacotherapy for OCD. Useful in ritualistic behaviour. 90% of patients make ‘worthwhile gains’.
Pharmacotherapy	Clomipramine and SSRIs: effects likely not seen for the first 6-8 weeks, with maximum effect by weeks 8-16. Augmentation with haloperidol, especially if tics are present. The relapse rate is high when medications are stopped.
Psychosurgery	Indicated for severe and intractable OCD. A common operation is a stereotactic cingulotomy. Subcaudate tractotomy is also used in some cases.

Neurobiology of OCD

Neuroimaging studies in OCD have revealed structural and functional abnormalities, most notably in the orbitofrontal cortices and basal ganglia (caudate nucleus) – the orbitofrontal circuit. These findings support the traditional description of OCD as a condition of dysfunctional habit circuits.

Increased activity in the orbitofrontal cortex is associated with concerns that lead to obsessive thoughts. The orbitofrontal cortex communicates with the basal ganglia. The basal ganglia and the orbitofrontal cortices pathway is simplified by viewing it as an excitatory direct pathway and an inhibitory indirect pathway between them. In OCD, the direct pathway is over-excitable, which increases the likelihood of both obsessions and compulsions (Pauls, 2013).

Brain imaging:

Increased blood flow in the:

• Frontal lobes (fronto-orbitoal gyrus)
• Basal ganglia (caudate)
• Anterior cingulate gyrus

Interestingly imaging has shown the caudate even with the increased blood flow is reduced in size bilaterally. These brain abnormalities are normalized with effective pharmacotherapy.

References:

(1) Brock, H. and Hany, M. (2020). Obsessive-Compulsive Disorder (OCD). [online] PubMed. Available at: https://www.ncbi.nlm.nih.gov/books/NBK553162/.

(3) Pauls DL, Abramovitch A, Rauch SL, Geller DA. Obsessive-compulsive disorder: an integrative genetic and neurobiological perspective. Nat Rev Neurosci. 2014 Jun;15(6):410-24. doi: 10.1038/nrn3746. PMID: 24840803.

(2) www.youtube.com. (n.d.). 2-Minute Neuroscience: Obsessive-Compulsive Disorder (OCD). [online] Available at: https://www.youtube.com/watch?v=BJshegpcFv8&t=114s [Accessed 31 Dec. 2022].