20th November 2023

Obsessive-Compulsive Disorder

OCD (ICD-10 F42) is characterised by either obsessions or compulsions, or both, is usually accompanied by anxiety and negatively impacts functioning. Let’s have a look at the definitions of obsessions and compulsions.

Obsessions – Frequent intrusive and distressing thoughts, images or impulses that the patient recognises as being their own. For example, the thought that a partner may be unfaithful.

Compulsions – Compulsive acts or rituals can be mental or behavioural. These repeated behaviours are used to counteract obsessions and not to provide enjoyment or complete beneficial tasks. For example, excessive cleaning or reciting a phrase in their head. These can take up a considerable portion of the patient’s day.

Predisposition, onset and maintenance

OCD is usually sudden onset and affects males and females equally. The age of onset is 20, with 70% of cases starting before the age of 25. It affects as much as 0.5-3% of the population. There is evidence from family and twin studies that patients may be genetically predisposed to developing OCD; however, no specific genes have been identified. It is possible that compulsions are learned responses to try and reduce the anxiety induced by obsessions, which leads us to psychoanalytical aetiology and Freud’s ‘obsessional neurosis’, where aggressive or sexual impulses lead to regression to previous psychosexual developmental stages. Following on from this, neurotic defence mechanisms commonly associated with OCD are undoing, isolation and reaction formation. Other explanations include dysregulation of serotonin and autoimmune response against the basal ganglia (see investigations below).

Improvement in symptoms is seen significantly in 20-30%, moderately in 40-50%, but chronically or even worsening in 20-40% of cases. Patients with worse prognoses often obey compulsions, have had OCD for a long time, were younger when it started or have psychiatric comorbidities. The rates of suicide are high, especially with concurrent depression.

Focused history

It can be useful to ask about specific compulsions; excessive cleaning, checking, counting, list making, arranging things specifically, touching them repeatedly or carrying out actions a specific amount of times are commonly reported. Or about specific obsessions: cleanliness, needing symmetry or order, violent or sexual thoughts, fear of doing the wrong thing or things that are against the law or their religion, that they have forgotten something or have left their property in an unsafe state. The patient would feel like the thoughts came from themselves, in contrast to thought insertion seen in schizophrenia. Again, it is important to know how much of their day is taken up by these thoughts or acts and how much harm or distress it is causing them. Patients may not recognise these undertakings as being separate from their daily routine.

Assessment of physical factors and investigations

You guessed it, just like panic disorder and GAD, there are no specific investigations for OCD, and imaging is not usually offered. Despite this, CT and MRI head imaging may reveal a bilateral reduction in caudate nucleus size. PET / SPECT scans show increased metabolism in the basal ganglia, orbitofrontal gyrus and cingulum.

Diagnosis

Presence of obsessions, compulsions or both that impact functioning or activities on most days for at least 2 weeks.

Treatment

Referral to specialist services should be completed to give access to clinicians who can undertake assessments and offer both psychological and biological treatments.

Biological treatment – SSRIs are equally as effective as intensive CBT in moderate impairment. These interventions can be offered in combination if monotherapy is inadequate. Second line pharmacological treatment is with clomipramine. Next, treatment with SSRI and antipsychotics such as aripiprazole or risperidone should be considered; following this treatment with a combination of clomipramine and citalopram is recommended by NICE.

Psychological treatment – In mild impairment, then up to 10 hours of individual or group CBT or exposure and response prevention therapy should be offered first. If this is unsuccessful, then biological treatment or more intensive therapy should be suggested.

Social treatment – Educating families and carers to build an understanding of the symptoms and support. OCD symptoms may be linked to religious beliefs; support and advice can be sought from appropriate religious leaders.

References

• Smyth R. (2019). Oxford Handbook of Psychiatry, fourth edition.
• NICE Clinical Guidelines, No. 31; National Collaborating Centre for Mental Health (UK).; Leicester (UK): British Psychological Society (UK); 2006. Obsessive-Compulsive Disorder: Core Interventions in the Treatment of Obsessive-Compulsive Disorder and Body Dysmorphic Disorder. https://www.ncbi.nlm.nih.gov/books/NBK56452/
• National Institute for Health and Care Excellence. (2020). Obsessive-compulsive disorder and body dysmorphic disorder: treatment. Clinical guideline [CG31]. https://www.nice.org.uk/guidance/cg31
• International Statistical Classification of Diseases, tenth revision (ICD-10), Version:2016, https://icd.who.int/browse10/2016/en#/F40-F48
• International Statistical Classification of Diseases, eleventh revision (ICD-11), Version 01/2023, https://icd.who.int/browse11/l-m/en#/http%3a%2f%2fid.who.int%2ficd%2fentity%2f1582741816
• Taylor DM; Barnes TRE; Young AH. (2021). The Maudsley Prescribing Guidelines in Psychiatry, fourteenth edition.