Autoimmune disease may almost double risk of mental ill health, study suggests
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Autoimmune disease may almost double risk of mental ill health, study suggests
The link may be explained by the chronic exposure to systemic inflammation that the autoimmune disease causes, researchers at the University of Edinburgh said. A growing body of evidence suggests that inflammation is linked to mental ill health, but many of the published studies have relied on small sample sizes, limiting their statistical power. Researchers drew on data from 1.5 million people in the Our Future Health programme from across the UK. The lifetime prevalence of any diagnosed affective disorder was significantly higher among those with an autoimmune disorder than it was among the general population. The reasons for this are unclear, but theories suggest that sex hormones, chromosomal factors, and differences in circulating antibodies may partly explain the differences. They added that it could be worth regularly screening people diagnosed with autoimmune diseases for mental health conditions.
The link may be explained by the chronic exposure to systemic inflammation that the autoimmune disease causes, researchers at the University of Edinburgh said.
A growing body of evidence suggests that inflammation is linked to mental ill health, but many of the published studies have relied on small sample sizes, limiting their statistical power.
To overcome this, researchers drew on data from 1.5 million people in the Our Future Health programme from across the UK. Participants completed a questionnaire that asked for personal, social, demographic, health and lifestyle information.
Health information included lifetime diagnoses for disorders including autoimmune and psychiatric conditions. Six autoimmune conditions were included in the study: rheumatoid arthritis, Graves’ disease (thyroid hormone disorder), inflammatory bowel disease, lupus, multiple sclerosis and psoriasis.
The mental health conditions the researchers were interested in were self-reported diagnoses of affective disorders, defined as depression, bipolar or anxiety disorder.
In total, 37,808 people reported autoimmune conditions and 1,525,347 did not. The lifetime prevalence of any diagnosed affective disorder was significantly higher among those with an autoimmune disorder than it was among the general population: 29% against 18%.
Similar associations emerged for depression and anxiety: 25.5% compared with just over 15% for depression, and just over 21% compared with 12.5% for anxiety. The prevalence of current depression and anxiety was also higher among people with autoimmune conditions.
While the prevalence of bipolar disorder was much lower, it was still significantly higher among those with autoimmune disorders than among the general population: just under 1% compared with 0.5%.
The prevalence of affective disorders was also significantly and consistently higher among women with autoimmune disorders than it was among men with the same physical health conditions: 32% compared with 21%.
The reasons for this are unclear. But the researchers, whose findings were published in the BMJ Mental Health journal, said theories suggest that sex hormones, chromosomal factors, and differences in circulating antibodies may partly explain the differences.
Overall, the risk for mental health conditions was nearly double in people with autoimmune conditions – between 87% and 97% higher. It remained high even after adjusting for potentially influential factors, including age, household income and parental psychiatric history.
The study was limited by a lack of available information on the time or duration of illness, making it impossible to determine whether autoimmune conditions preceded, co-occurred with or followed affective disorders.
No direct measurements of inflammation were made either, making it impossible to establish the presence, nature, timing or severity of inflammation.
The researchers concluded: “Although the observational design of this study does not allow for direct inference of causal mechanisms, this analysis of a large national dataset suggests that chronic exposure to systemic inflammation may be linked to a greater risk for affective disorder.
“Future studies should seek to determine whether putative biological, psychological, and social factors – for example, chronic pain, fatigue, sleep or circadian disruptions and social isolation – may represent potentially modifiable mechanisms linking autoimmune conditions and affective disorders.”
They added that it could be worth regularly screening people diagnosed with autoimmune diseases for mental health conditions, especially women, to provide them with tailored support early on.
Autoimmune disease almost doubles the risk of depression and anxiety
People with autoimmune conditions were almost twice as likely to report having had depression, anxiety, or bipolar disorder at some point in their lives compared to people without these conditions. Inflammation is thought to be a driving force behind autoimmune diseases, in which the immune system mistakenly attacks the body’s own healthy cells. The findings suggest a need for integrated mental and physical healthcare in people with autoimmune diseases. Because the data used was from people living in the UK, the findings may not apply to other countries. The study does have limitations, because this study was observational and not experimental or longitudinal, it cannot prove that autoimmune diseases cause mental illness. The integration of mental health supports into treatment plans might help detect and manage affective disorders in this high-risk group.
Previous research has indicated that there’s a link between inflammation and psychiatric disorders such as depression and bipolar disorder. Inflammation is thought to be a driving force behind autoimmune diseases, in which the immune system mistakenly attacks the body’s own healthy cells.
A new study led by the Center for Clinical Brain Sciences at the University of Edinburgh in Scotland investigated whether having an autoimmune disease was linked to a higher risk of mental health issues, specifically depression, anxiety, or bipolar disorder (collectively known as affective disorders).
The researchers obtained data from 1,563,155 adults living in the UK who were part of the Our Future Health study cohort. Participants were split into two groups: 37,808 individuals with a self-reported lifetime diagnosis of one of six autoimmune diseases, and 1,525,347 without such a diagnosis. The autoimmune diseases included were rheumatoid arthritis, Graves’ disease, inflammatory bowel disease, lupus, multiple sclerosis, and psoriasis. The presence of an autoimmune disease was used as a proxy for chronic inflammation in the absence of direct measurements of participants’ inflammatory markers.
People with autoimmune conditions were almost twice as likely to report having had depression, anxiety, or bipolar disorder at some point in their lives compared to people without these conditions (28.8% vs 17.9%). The autoimmune group also had higher levels of current depression and anxiety symptoms. Depression was reported by 18.6% compared with 10.5% in the general population; anxiety was 19.9% versus 12.9% in the general population. These results held true even after adjusting for factors like age, sex, ethnicity, income, chronic pain, family history of mental illness, and social isolation. Women with autoimmune conditions were found to have significantly higher rates of affective disorders than men with the same physical conditions.
The study’s findings suggest some practical steps that could be taken to address the problem. First, regular mental health screenings should be part of standard care for people with autoimmune diseases, especially women. The integration of mental health supports into treatment plans might help detect and manage affective disorders in this high-risk group. Additionally, healthcare professionals may need to pay particular attention to the psychological well-being of patients managing chronic inflammatory diseases.
The study does have limitations. Importantly, because this study was observational and not experimental or longitudinal, it cannot prove that autoimmune diseases cause mental illness, or vice versa. The use of self-reported data can introduce bias or inaccuracy. Autoimmune diseases were used as an indirect marker of chronic inflammation, rather than direct measures using inflammatory biomarkers, such as interleukin-6 (IL-6). It wasn’t possible to tell whether mental health issues came before, after, or at the same time as the autoimmune conditions. Because the data used was from people living in the UK, the findings may not apply to other countries.
Despite the obvious limitations of the study, it does strengthen the evidence linking chronic inflammation, via autoimmune disease, to a higher risk of affective mental health disorders. While more research is needed to untangle the exact mechanisms and timelines, the findings suggest a need for integrated mental and physical healthcare in people with autoimmune conditions.
The study was published in the journal BMJ Mental Health.