What Causes OCD?

As with numerous other diseases and disorders, there are multiple factors that contribute to the development of OCD. Genetic abnormalities appear to be important; DNA research has found a number of genes that may play roles in OCD. Also, first-degree family members of OCD patients have an increased risk of OCD. Environmental factors, socioeconomic status and level of education also have been statistically linked to OCD. A single causative factor has not been found in OCD. Rather, it is likely that the above factors and other biological features contribute to OCD behaviours, and also determine the types of symptoms, severity, response to treatments, and course of the illness. While genetic differences and environmental factors may explain some of the “why” about OCD, the “how” – the mechanisms and biological pathways through which OCD symptoms manifest – is just as important to understand, particularly in the development of better and more focused treatment strategies.

The typical dysfunctional thoughts and actions in OCD appear to result from abnormal levels of or defective neurotransmitters in the brain. Neurotransmitters, derived from amino acids, are the signalling molecules used by nerve cells to communicate and coordinate their activities. They mediate all aspects of brain activities, including things like thought formation, memory, emotion, learning, physical movement, and virtually all other brain functions.


Imbalances or disturbances of several of these neurotransmitters appear to be central in the development of OCD. The neurotransmitters that play important roles in OCD include glutamate, gamma-aminobutyric acid (GABA), serotonin (5-HT), dopamine, and to a lesser extent, norepinephrine. These neurotransmitters are the targets for many of the drugs that have been a cornerstone of OCD treatment.

OCD Subtypes

Although patients with OCD share some clinical characteristics, they frequently have symptoms
that are distinctive. Grouping patients according to their principal symptom profile is useful for:


Obsessive Thoughts About Contamination, Washing And Cleaning Compulsions

Patients with this subtype have obsessive thoughts that they are contaminated, often from..

Obsessive Thoughts About Symmetry, Compulsions Of Ordering And Arranging

People in this group suffer from intrusive thoughts that if you fail to properly sort or balan…

Obsessive Thoughts About Doing Harm, Checking Compulsions

This subtype is associated with great anxiety and distress from strong yet irrational beliefs …

Obsessive Disturbing Thoughts, Mental Compulsions

In this group, the obsessive thoughts usually have unacceptable (“taboo”), religious, sexual…

Obsessions with excessive attachments to physical objects; Hoarding compulsions

In this subgroup, individuals usually fear discarding things that might be useful to them so…