Obsessive Compulsive disorder

The psychiatric condition obsessive-compulsive disorder (OCD) is estimated to be present in 1.2% of the UK population. This condition has been oversimplified in the past and present media as being only an obsession with cleanliness or order, whereas in reality, it can have potentially a diverse list of presentations. The key to the diagnosis is whether there is a disorder, therefore this is not a label for those possessing only personality traits of being meticulous or neat. This is a condition which is separate from the individual’s personality, which impacts daily function and often has a profound effect on mood. This article will cover the different aspects of the disorder and its treatment.


The ICD-10 code for obsessive-compulsive disorder is F24 and it defines the disorder as having the following features:
-The individual has obsessional thoughts and/or compulsive acts
Obsessions are repetitive ideas, images or impulses which cause significant distress to the individual
Compulsions are either mental or physical acts which are ritualised or stereotyped in order to relieve foreseen harm of the obsession to the individual or common to others. 
-Attempts to resist these obsessions or compulsions are usually unsuccessful and do not relieve the anxiety caused.
-The individual has insight into the thoughts and actions as being irrational or purposeless but attempts to resist this cause further distress.

OCD Mechanism


The obsessions seen in OCD are typically ego-dystonic: they are thoughts and behaviours that are distressing towards one’s morality, self-identity, and reality. An example of this would be repetitive thoughts of harming another, despite them believing this is immoral or against their positive feelings towards that individual. This can lead them to perform a ritual (compulsion) to attempt to stop this from happening. In practice, the obsession may appear like a delusion, but in these cases, the individual has insight into this not being a reality, but they are unable to lose these intrusive thoughts or neutralising behaviours and rituals. A patient suffering a delusion will lack insight into the thought conflicting with their reality. Delusions are not a typical feature of OCD and would indicate another condition (such as psychosis or mania), or present following a significant life event or trauma. A clinician should always bear in mind that a patient having one mental health condition does not exclude the presence of another. Another distinguishing characteristic of an obsession versus a delusion is that individuals experiencing delusions can feel positive from them in some cases, whereas typically in OCD the obsessions are felt as extremely negative by the individual and have a detrimental effect on their wellbeing.

FormIdeas, thoughts, imagesIdeas, thoughts
Content ExamplesEgo-dystonic Persecutory, grandiose, somatic, erotomania
DistressPresentPresent/ absent
Table outlining how to distinguish an obsession (in OCD) from a delusion (seen in other disorders)


The compulsions the person partakes in can be mental or physical. Mental compulsions are typically neutralising, they counteract the obsessional thought, with the aim of relieving anxiety. Whereas physical acts can be to counteract the perceived obsession, such as cleaning to relieve the thought of contamination. Both types of rituals are distressing for the person in several ways. They often fail to relieve the anxiety and use a lot of the individual’s time and energy, which can have repercussions for their daily functioning, work and relationships.

Themes of Obsessions and Compulsions

Some of the themes of obsessions are listed below, there is vast diversity owing to their antagonistic relation to an individual’s own personal ideals and circumstances. There is commonly an inflated sense of responsibility perceived by the individual, that they have a moral duty to protect others. They view their intrusive and uncontrollable obsessions as their fault and that they are at fault if the perceived harmful consequence of them occurs.  

ThemesObsession examplesCompulsion examples
Contamination and cleanlinessThoughts or images of harm or death of relatives (often children) due to infection or contamination.Hand washing and sterilising clothing until the individual feels relief or believes their family will now be safe. This might also involve removing clothing at the door that they have worn outside.
Physical safetyChecking that doors and windows are not locked, and oven, gas or lights are on.Checking multiple times that doors are locked, taps off, oven and gas off, lights off or windows locked.
HoardingThoughts that if they throw an item away it will be a disaster if they need it, despite evidence to the contraryItem hoarding, even to the point of encroachment on daily living activities.
Physical HarmIntrusive thoughts or images of harming others, such as murder or paedophilia are incongruent with their moral values.Neutralising thoughts or behaviours
Scrupulosity/ ReligiousObsessions that are not congruent with the individual’s religious or moral values. Triggering anxiety that they should be punished by their God or they are not a worthy follower.Praying excessively, conducting neutralising prayers, and overcompensating with engagement in moralistic activities.
Overanalyses of previous actionsRepeated thoughts about previous actions, with prominent cognitive distortions, such as great offence being taken by another despite the evidence to the contrary.Mental replaying of events, apologising excessively to others, acts of forgiveness to others.
Order and SymmetryDiscomfort or anxiety with the way something is arranged, fear of disorderRearranging items to get the ‘right fit’

OCD has sometimes been coined ‘the doubting disorder’, meaning that these patients often doubt that they have done a task which in reality is completed. This leads to repetition of ritual behaviours, such as checking the locks on doors multiple times.

PureO type

You may come across people with a less common form of OCD, named the PureO type. These individuals experience the obsessions without the compulsions. Be aware that some people may not have physical compulsions, and that this does not rule out the disorder or mean that the individual is less distressed.

Specific Presentations

The individual may have conflicts with their partner or family members due to their obsessions or compulsions. They may have distressing obsessions about their relative coming to harm which may be projected into the relationship. Relatives may also complete tasks to avoid the distress of the individual, which may lead to confrontation or a perceived imbalance. Individuals with OCD may also seek reassurance consistently from those around them, which can further affect the relationship dynamic.

Psychiatric comorbidities:
A mood disorder, such as depression or an anxiety disorder can co-exist or be a consequence of the underlying obsessive-compulsive disorder. These patients may also exhibit features of eating disorders due to obsessions over the content of food, with restriction of their diet to certain food groups, leading to susceptibilities to physical health problems.

Perinatal period:
Patients with OCD during the perinatal period can be more susceptible to anxiety, intrusive thoughts and low mood than the general population. This period may also initiate obsessive and compulsive behaviours. Referral to specialist services can be important in these cases due to the unique needs of this population. As a junior in obstetrics, you may come across these patients and should have a low threshold to refer to specialist services, due to the increased risk of mood disturbance in the perinatal period. These patients may be reluctant to talk about their thoughts due to fear of being judged as an unfit parents and so this should be recognised, and reassurance given.


Studies indicate that earlier intervention and treatment of OCD has more favourable outcomes, but in reality, most individuals are diagnosed after many years with the disorder. Treatment for OCD is typically a combination of Cognitive behavioural therapy (CBT) with Exposure response prevention (ERP) and a high dose Selective Serotonin Reuptake Inhibitor (SSRI), such as Sertraline.
Exposure response prevention involves the patient facing a situation which triggers obsessions for the patient, for example seeing a public toilet, then preventing them from carrying out the compulsion, such as washing their hands. This process is repeated, with the levels of anxiety documented, with the aim of reducing the anxiety caused with each exposure by breaking the cycle of obsessions triggering rituals.

Some patients find it difficult to engage with treatment owing to some behaviours being perceived externally as beneficial, for example washing hands during the COVID-19 pandemic. Another example might be the obsessions and the compulsions being beneficial at work, for example, meticulous checking of documentation and filing in a job might enable them to be better prepared at work and therefore high achieving.

Take-home messages

-Be able to differentiate obsessive-compulsive disorder (OCD) from personality traits of neatness or order. It is the effect of these obsessions, with or without compulsions, on the individual’s daily functioning which are key criteria for the diagnosis.
-Be aware that there does not have to be a physical compulsion for an individual to have OCD, they may only have mental compulsions, PureO OCD.
-Remember to assess for additional psychiatric comorbidities, such as mood disorders and eating disorders and conduct a risk assessment.
-This condition can be difficult for patients to discuss due to distress and due to fear of judgment from others.
-The mainstay of treatment currently is a combination of a high-dose SSRI and CBT with Exposure response prevention.

Media sources related to this topic

The OCD Stories, contains interviews with patients with lived experience of OCD, as well as professionals working in the area. Hosted by Stuart Ralph.

The man who couldn’t stop: the truth about OCD – David Adam
Because We Are Bad: OCD and a Girl Lost in Thought – Lily BaileyTelevision:
Pure– Channel 4 drama about a young woman with Pure O form of OCD.


-Perinatal Obsessive-Compulsive Disorder: Epidemiology, Phenomenology, Etiology, and Treatment. Neha Hudepohl, Joanna V MacLean, Lauren M Osborne, Current Psychiatry Reports 2022.
-Early intervention in obsessive-compulsive disorder: From theory to practice. Leonardo Fontenelle, Homberto Nicolini, Vlasios Brakoulias, Comprehensive Psychiatry 2022.

Written by Dr Isobel Platt (FY1) and Dr Anya Baig (FY1)
Edited by Dr Fergus Lewis (Psychiatry SpR)

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