Previous studies have found excess deaths in people with OCD, but the specific causes of death had been poorly researched – maybe with the exception of suicide. Notably, people with OCD have similar suicide rates to people with other mental health disorders.
OCD affects about 2% of the population. People with the condition have distressing intrusive and repetitive thoughts (such as a fear of being contaminated or becoming aggressive towards others) and feel compelled to perform time-consuming rituals to reduce the discomfort caused by the thoughts, such as cleaning, repeating or checking.
The disorder significantly impairs daily life, affecting relationships, social activities and the general ability to function.
My colleagues and I at the Karolinska Institutet in Sweden aimed to understand the specific natural and unnatural causes of death contributing to the reported elevated mortality rates in OCD. We used Swedish population registers, which include administrative and healthcare data from the whole population, to compare a group of 61,378 people who had received a diagnosis of OCD with 613,780 people without OCD.
We followed both groups for more than four decades (from 1973 to 2020) and found that people with OCD died at an earlier average (mean) age than those without OCD (69 v 78 years).
The risk of death during the study period was 82% higher in the group with OCD, compared to the group without OCD. The increased risk of death was attributable to both natural (31% increased risk) and unnatural causes (230% increased risk).
For the first time, we were able to identify specific causes of death due to natural causes. People with OCD had increased risks due to lung diseases (73%), mental and behavioural disorders (58%), diseases of the urinary and reproductive organs (55%), endocrine, nutritional and metabolic diseases (47%), diseases of the blood vessels (33%), nervous system (21%) and digestive system (20%).
Intriguingly, the risk of death due to cancer was 13% lower in those with OCD. The reason this risk goes in the opposite direction is not known.
Among the unnatural causes of death, suicide was the main contributor to the increased mortality. Those with OCD, compared to those without, had a nearly fivefold increased risk of dying by suicide. Also, people with OCD had a 92% increased risk of dying due to accidents, including traffic accidents or falls.
The results held even after we took mental health disorders other than OCD – for example, anxiety, depression and substance use disorders – into account.
Also, when we compared the OCD group with their siblings without OCD, the results remained largely unchanged. This confirms that our results cannot only be attributed to any accompanying mental health disorders or genetic or environmental factors shared between families, but that are likely to be related to OCD itself.
Although these are not positive findings for people with OCD, it’s important to note that the proportion of people dying of each cause was relatively small, even if compared with the group without OCD it translated to a higher risk.
For example, during the study period, 2.5% of people with OCD died due to circulatory system diseases (such as heart attacks and strokes), which is a low percentage. Nonetheless, this percentage is higher than the 1.8% of deaths by this cause in the group without OCD.
Even so, it is not acceptable that people with OCD have to face these extra risks. I hope that these results spur healthcare professionals into action and contribute to people with OCD receiving better care.
Importantly, most of the causes of death that showed an increased risk are related to non-communicable diseases (for example, cardiovascular diseases, diabetes, chronic lung diseases, mental disorders, neurological disorders) and to external causes (for example, suicide, accidents), which can be classified as preventable.
People with OCD need to be aware of these risks. This may motivate behavioural changes – such as getting more exercise and having a healthy diet – that can play a role in preventing ill health and early death.
email@example.com has received funding from the Swedish Research Council for Health, Working Life and Welfare (FORTE), Region Stockholm (ALF funding), the Swedish Society of Medicine (Svenska Läkaresällskapets), and Karolinska Institutet. She also receives royalties for contributing articles to UpToDate and Wolters Kluwer Health and for editorial work from Elsevier, outside the submitted work.