Autoimmune diseases linked to higher mental health risk

People with autoimmune diseases face nearly double the risk of depression, anxiety and bipolar disorder, with women significantly more affected than men, large-scale UK data shows.

An analysis of 1.5 million participants from the Our Future Health dataset found that 29 per cent of those with autoimmune conditions self-reported a diagnosis of a mental health disorder, compared to 18 per cent of those without.

The study examined six autoimmune conditions – rheumatoid arthritis, Graves’ syndrome (a thyroid condition), inflammatory bowel disease, lupus, multiple sclerosis and psoriasis – and found consistent associations with affective disorders, including depression, anxiety and bipolar disorder.

Among those with autoimmune conditions, 25.5 per cent reported a diagnosis of depression compared to just over 15 per cent of those without.

Anxiety was reported by just over 21 per cent versus 12.5 per cent.

Although bipolar disorder was less common overall, it was still reported at twice the rate: just under 1 per cent among those with autoimmune conditions versus 0.5 per cent in the general population.

Women were particularly affected, with 32 per cent of those with autoimmune diseases reporting an affective disorder, compared with 21 per cent of men with the same conditions.

Autoimmune diseases occur when the immune system mistakenly attacks healthy tissue, leading to chronic inflammation.

In this study, an autoimmune diagnosis was used as a proxy for long-term systemic inflammation, as no direct biomarkers were measured.

 The researchers stated: “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.”

Parental history was also considered.

Participants with autoimmune diseases were more likely to report psychiatric diagnoses in their biological parents: 8 per cent versus 5.5 per cent for fathers, and 15.5 per cent versus 11 per cent for mothers.

Women may be at particular risk due to biological differences in immune and hormonal systems.

The researchers noted: “Women (but not men) with depression exhibit increased concentrations of circulating cytokines and acute phase reactants compared with non-depressed counterparts.”

Cytokines are inflammatory proteins thought to play a role in the link between inflammation and mental health.

The researchers wrote: “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.”