Dementia risk among RA patients is in decline
medwireNews: The incidence of dementia in patients with rheumatoid arthritis (RA) has declined since the 1980s and 1990s, bringing the risk more in line with that of the general population, research shows.
The study authors analyzed the medical records of 897 people (mean age 56 years; 69% women) diagnosed with RA between 1980 and 2009, and 885 controls who were matched on age, sex, and calendar year, all of whom lived in Minnesota and were part of the Rochester Epidemiology Project.
RA diagnosis was manually verified, and the RA patients were followed up for a median of 15 years and the controls for a median of 16 years.
Among the RA patients, the 10-year cumulative incidence of dementia, defined as two ICD-9/10 codes for Alzheimer’s disease and related dementias (ADRD) at least 30 days apart, decreased from 12.7% between 1980 and 1989 to 7.2% between 1990 and 1999 and further still to 6.2% between 2000 and 2009. This translated to a 14% and 34% decline in incident dementia in the 1990s and 2000s, respectively, when compared with the 1980s.
“Interestingly, this decrease in dementia incidence over time coincides with both a decline in dementia over time in the United States and Europe, as well as better RA disease control over the same time frame,” say the researchers.
They add: “Use of [biologic] DMARDs may also contribute to this decline, perhaps by lowering cardiovascular risk factors.”
Dementia incidence rates also decreased in the general population controls, falling from 9.3% in the 1980s to 5.0% and 7.1% in the 1990s and 2000s, respectively. This equated to a 25% and 3% decrease in risk for dementia in the 1990s and 2000s when compared with the 1980s.
Comparing dementia risk in the two groups, the researchers found it was increased a significant 37% among patients with RA when the 30-year study was considered as a whole, but they note that after adjusting for factors including age, sex, and cardiovascular events, the difference between the two groups narrowed over time.
The risk for dementia was a significant 60% and 72% greater for RA patients than the general population in the 1980s and 1990s, respectively, whereas there was no significant difference in risk between those with and without RA in the 2000s.
Elena Myasoedova (Mayo Clinic, Rochester, Minnesota, USA) and team say that “[o]lder studies show a positive association between RA and dementia, whereas newer studies show no association, or even a reverse association,” and add that “[t]he increased risk for ADRD among individuals with RA in the 1980s and 1990s, but not 2000s, may explain the discrepancy in existing literature on this topic.”
They write in Seminars in Arthritis and Rheumatism: “Together, these findings of decreased dementia risk over time, and in comparison to individuals without RA, suggest that chronic, systemic inflammation may be important in dementia pathogenesis.”
Myasoedova et al conclude that “[f]urther studies should investigate this association using validated algorithms for dementia case identification, and should also elucidate the role of inflammation, autoimmunity, and anti-rheumatic treatments in risk of dementia.”
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