Introduction 

Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric condition, which results in serious life impairment for the individuals living with it and affects around 2% of the population.¹ People with OCD may exhibit distressing intrusive thoughts and feel compelled to practice various compulsions/rituals to relieve the arising discomfort.² Unfortunately, obsessive-compulsive symptoms tend to be difficult to assess as they are commonly internal and can be hard to recognise even for the patients experiencing them.¹ As distressing intrusive thoughts are one of the main factors of the disease, this article further sheds light on this unseen internal struggle.

Understanding the obsessive-compulsive disorder (OCD)

Disease overview

As the name suggests, the key components exhibited by most OCD patients are persistent obsessions (thoughts, urges, or images) and compulsions (repetitive behaviours or mental acts) they perform to neutralise the invasive mental content. The obsessions arise in an unwanted way and cause strong distress, which is why people with OCD either try to ignore or suppress them or resort to various compulsions.²

One of the prominent OCD features is pathological doubt regarding a situation, action, or stimulus, ranging across the different OCD subtypes. However, this is especially evident among patients exhibiting checking compulsions. This can further relate to a strong difficulty in tolerating situations that are ambiguous or uncertain, driving people with OCD to engage in compulsions with the hope of restoring certainty.³

OCD is one of the most disabling anxiety disorders with its severity frequently increasing if left untreated. One of the factors increasing the disease burden is the non-medical perception of OCD, causing patients to experience stigmatisation. Humans experience certain obsessive thoughts and compulsive actions as part of everyday life, for instance, checking that the door is locked or ensuring that the stove is switched off before leaving the house; this serves a biological survival value. However, for someone with OCD, obsessive thoughts become unavoidable, oftentimes scary, violent, intrusive, and ego-dystonic, thus seriously impairing normal functioning and life quality.⁴ 

What causes OCD?

The cause for OCD is not fully known but likely involves genetic factors as its heritability is confirmed by twin and family studies. Human and mouse studies show that mutations in the NMDA receptor can increase OCD-like behaviour.⁵ Additionally, OCD patients appear to share polymorphisms of the glutamate receptor gene, SLC1A1, which encodes a glutamate transporter, excitatory amino acid carrier 1, found in various areas of the brain. It appears that the brain regions, most involved in OCD, normally assist with emotion regulation and cognitive control. It is therefore possible that alterations in these regions could mediate the anxiety and the misappraisal of threat in OCD patients.⁶

However, genetics are not the only discussed cause. It has been suggested that an interplay between genetic and environmental risk factors may lead to OCD, particularly, exposure to traumatic and stressful life events. Changes in routines and increased general stress are linked to OCD development and severity. Some researchers have shown elevated cortisol levels to be a hallmark of OCD.⁷

Dysfunction of the following neurotransmitters has also been associated with OCD:

• Overactivity of dopaminergic and glutamatergic neurotransmission
• Reduction in GABAergic and serotonergic neurotransmission

OCD is linked to other neurological disorders, especially the ones affecting the cortico-striato-thalamo-cortical circuitry, for instance:⁵

• Parkinson’s disease
• Epilepsy
• Tourette’s syndrome 

OCD symptom dimensions

OCD symptoms can be grouped into the following dimensions:¹⁰

• Contamination obsessions resulting in hygiene compulsions
• Symmetry obsessions resulting in arranging, ordering, symmetry, counting compulsions
• Taboo-related obsessions and compulsions revolving around violence, religion, sex
• Doubt/harm obsessions resulting in checking compulsions 

OCD and intrusive thoughts 

What are intrusive thoughts?

Intrusive thoughts are one of the key components of OCD and fall under the “obsessive” part of the disease. The thoughts arising in OCD patients typically surround things that they would be repulsed to do or situations that they would hate to happen.² Some examples of such thoughts include harming someone in a violent/sexual manner, despite not wanting or intending to, or believing to have done something blasphemous.¹¹ In OCD, a scary thought about potential harm happening to one’s child becomes highly meaningful. This leads them to the conclusion of being an awful person and a danger to the child, further creating a vicious cycle.¹²

Due to the inability to stop these thoughts, the patients ruminate endlessly and develop various compulsions to either ensure that the unwanted events do not happen or to satisfy their obsessions.⁴ The compulsions are either strongly excessive or not even related to the things that they are meant to neutralise or prevent.²

While intrusive thoughts are also experienced by the general population, the difference is that OCD patients appraise their thoughts in a more dysfunctional way, compared to non-clinical individuals. For instance, those with OCD assign more importance to the arising thoughts and tend to feel responsibility over having them. This makes them more emotionally disturbed, driving them to try to control themselves in some way. It was shown that individuals with OCD (or subclinical OCD scores) were more likely to take part in cognitive (mental compulsions, thought suppression) and behavioural (ordering, washing) strategies to deal with the intrusive thought-induced anxiety or to dismiss their frequency, compared to non-clinical individuals. One of the cognitive strategies – thought suppression – has been shown by various studies to be an ineffective strategy for intrusive thought removal in both clinical and nonclinical cases.^8,9

Given that OCD can resemble psychosis as intrusive thoughts lack insight and involve delusional beliefs, it is essential to understand the differences between OCD-associated intrusive thoughts and delusions linked to psychotic disorders (e.g., schizophrenia). The key distinguishing factor is that OCD compulsions are performed to decrease anxiety triggered by images, thoughts, or impulses. Additionally, the presence of disorganised speech, hallucinations and affective flattening would point to schizophrenia, not OCD.⁶

Current treatment options 

Many clinicians consider a combination of cognitive behavioural therapy (CBT) together with medication management to be a more effective treatment strategy than either of them on their own.¹³ 

Behavioural treatment

Exposure and response prevention (ERP) is considered to be the best-proven behavioural treatment option for OCD. It involves presenting patients with stimuli that would normally provoke their anxiety and obsessions and then preventing them from acting upon their usual compulsions.¹³   

Pharmacotherapy 

Selective serotonin reuptake inhibitors (SSRIs) are considered to be the first-line pharmacotherapy for OCD patients and various studies demonstrate their effectiveness. Some of the SSRIs mentioned in the literature for OCD treatment include:^13,14

• Fluoxetine
• Fluvoxamine
• Sertraline
• Citalopram
• Escitalopram
• Paroxetine
• A tricyclic antidepressant – clomipramine – is also used

OCD resistance to treatment

OCD that is resistant to CBT and SSRI treatment remains a common issue, bringing grim consequences to the patients and their families. While alternative strategies have been attempted, there is no clear consensus regarding the best option for these patients.¹³ Nonetheless, research studies have suggested serotonin-norepinephrine reuptake inhibitors (SNRIs) as potential second-line alternatives for refractory patients. In particular, venlafaxine and duloxetine have been implicated to have some efficacy in OCD treatment. SNRIs have yet to be approved by the U.S. Food and Drug Administration (FDA) or the National Institute for Health and Care Excellence (NICE) to treat OCD specifically, therefore further research is required to establish its efficacy and safety.

The following is a potential regimen for people who are resistant to first-line treatment:¹⁵

1. Optimising the dose of SSRIs and selecting the correct trial length
2. Switching to an alternative medication option (another SSRI/clomipramine), then possibly trying a SNRI 
3. Augmenting the treatment with an additional medication, for instance, a glutamate modulator or an antipsychotic

Additionally, ERP and somatic treatment options, such as repetitive TMS and neurosurgery (in extreme cases), are important to keep in mind, with the possibility of effectively combining them with the chosen pharmacotherapy.¹⁵ 

OCD trivialisation  

Unfortunately, the literature shows that the public’s knowledge of OCD is generally poor. This debilitating disease also appears to be often trivialised in the media. These misperceptions can negatively impact OCD patients and contribute to them being ill-equipped to recognise their symptoms and further seek help. Therefore, educating the public about the disease as well as evidence-based treatment is essential to encourage people to seek help and subsequently improve disease outcomes.¹⁶

A study, exploring the illness perceptions of the family members of OCD patients, noted that:¹⁷

• Some participants appeared to use the term ‘OCD’ to help describe certain behaviours present in people not experiencing clear disability and distress. This is further suggestive of perceiving OCD more as a ‘trait’ of varying degrees rather than an illness. 
• On the other hand, other participants were frustrated with the recent popularisation of OCD, for instance in the media, where this term is used to describe the ritualistic/meticulous behaviour of individuals without an OCD diagnosis. They also believed that this misuse of the OCD label could further lead to a trivialisation of a debilitating condition. 

It is therefore essential to raise disease awareness among the general public to avoid the trivialisation of a serious, debilitating mental disorder. This could further help OCD patients to seek treatment and receive the support they need and deserve.

 Summary

• OCD is one of the most disabling mental anxiety disorders, causing ego-dystonic, unavoidable, obsessive thoughts and further driving compulsive actions, which seriously impairs patients’ quality of life. 
• Intrusive thoughts are the obsessive part of the disease and often surround things that the patients would normally be repulsed by, for instance, harming someone violently.
  • Due to the extreme discomfort and the inability to stop these thoughts, OCD patients engage in various compulsions to ensure that the unwanted things do not happen. 
• Key treatment options include a behavioural therapy approach – ERP – as well as pharmacotherapy with SSRIs or clomipramine. Unfortunately, treatment-resistant OCD remains an issue. 
• To ensure that OCD patients recognise their symptoms and seek treatment, it is important to educate the general public regarding the disease and to stop its trivialisation from occurring in the lay media.