Being genetically at-risk for rheumatoid arthritis later in life appears to be linked to lower cognitive ability in childhood, a study shows.
It is well-known that patients with rheumatoid arthritis are more likely to experience memory and attention problems – but the cause and effect relationships are difficult to tease apart.
One theory is that the RA disease itself (or, alternatively, the drugs used to treat RA) cause changes to brain function in adults.
Another theory is that the genes associated with RA cause cognitive impairment early in life before the onset of RA symptoms.
If this were the case, children with RA genes might have a higher proportion of attention deficit disorders and lower IQs than their peers even though they won’t develop RA until decades later.
A study published in JAMA in June has gone some way towards backing up this second theory.
The retrospective study of around 8,000 kids found that having RA genes was linked to lower IQ, hyperactivity and inattention at a young age.
Because these children didn’t yet have RA symptoms, the disease processes couldn’t be driving these cognitive issues – it had to be the genetics at work, according to the researchers.
By comparison, kids with a genetic predisposition for inflammatory bowel disease or multiple sclerosis were not more likely to have cognitive impairment in the study.
“These findings support an association between genetic risk for RA and neural phenotypes, suggesting that cognitive impairment in RA is not simply secondary to disease-related processes or treatment effects,” the authors said.
“These results may suggest that genetic susceptibility for RA might affect psychological well-being in early life and reinforce the emerging link between mental health and the immune system.”
One limitation of the study, according to the researchers, was that it didn’t account for parents who had rheumatoid arthritis affecting the upbringing of the child. However, when the researchers excluded kids who had mothers with RA, it didn’t affect the results.