Autoimmune Diseases Increase Hippocampal Sclerosis Risk in Nonagenarians

According to a study published in Neurology, rheumatoid arthritis and thyroid disease were found to increase the risk for hippocampal sclerosis (HS) in a cohort of patients aged ≥90 years with dementia. Study researchers also found that Lewy body disease (LBD) represented the only pathology associated with HS in these older patients with dementia.

Patients with dementia aged ≥90 years who resided in Laguna Woods, California, and underwent in-person evaluations and postmortem brain examinations in The 90+ Study were enrolled (N=134). The researchers identified patients with HS pathology (n=35) and without HS pathology (n=99). Participants were compared in regard to their 6-month cognitive and physical statuses, which were assessed with a neurologic examination, self or informant-completed questionnaires for medical history and demographics, and a neuropsychological test battery.

The mean duration of dementia was longer among individuals with HS vs those without HS (6.7 years vs 4.0 years, respectively; odds ratio [OR] 1.26; 95% CI, 1.11–1.42; P <.001). Patients with a history of autoimmune diseases, including arthritis and thyroid disease, were more likely to have HS (OR 3.15; 95% CI, 1.30–7.62; P =.011). Additionally, those with HS were more likely to have high thyroid-stimulating hormone (OR 4.94; 95% CI, 1.40–17.46; P =.013) or high thyroid antibodies (OR 3.45; 95% CI, 1.09–10.88; P =.035).

A greater likelihood of HS was also observed for patients with Lewy body disease (LBD) pathology (OR 5.70; 95% CI, 1.22–26.4; P =.027). Finally, the investigators found that a history of depression (OR 0.20; 95% CI, 0.06–0.65; P =.008) and cerebrovascular disease (OR 0.40; 95% CI, 0.16–0.99; P =.048) were associated with a lower likelihood of HS.

Limitations of the study include its inclusion of patients from a single geographic location in California as well as only including patients over the age of 90 years, which may potentially reduce the generalizability of the findings.

“The observed association between HS and autoimmune conditions deserves special attention due to the potential implications on the pathogenesis mechanisms of HS that might lead to effective prevention/treatment strategies should future clinical and pathologic studies confirm inflammation or autoimmunity as risk factors for HS,” the researchers concluded.

Reference

Trieu T, Sajjadi SA, Kawas CH, Nelson PT, Corrada MM. Risk factors of hippocampal sclerosis in the oldest old: The 90+ Study [published online October 12, 2018]. Neurology. doi: 10.1212/WNL.0000000000006455.88