Infections a risk factor for dementia

Individuals who have been hospitalized with infection appear to be at higher risk of dementia compared with their peers who are unexposed to infections, as reported in a study.

The present analysis used data from the community-based Atherosclerosis Risk in Communities (ARIC) study and included 15,688 participants who were free of dementia at baseline (mean baseline age 54.7 years, 55.2 percent female, 26.8 percent Black).

Researchers determined the incidence of dementia through surveillance of ICD-9 and ICD-10 hospitalization and death certificate codes, in-person assessments, and telephone interviews. They also conducted a sensitivity analysis that excluded cases occurring within 3 years or beyond 20 years from exposure.

Over a follow-up of 32 years, 5,999 participants (38.2 percent) were hospitalized for infection. Dementia occurred in 2,975 participants (19.0 percent) at a median of 25.1 years after baseline. The incidence rate of dementia was higher among the group of participants who were exposed to infection than among the unexposed group (23.6 vs 5.7 events per 1,000 person-years).

In crude and adjusted Cox regression models, hospitalization for infection was associated with a higher risk of incident dementia (hazard ratio [HR], 2.02, 95 percent confidence interval [CI], 1.88–2.18; p<0.001 and HR, 1.70, 95 percent CI, 1.55–1.86; p<0.001).

Results of the sensitivity analysis were consistent with the main findings (adjusted HR, 5.77, 95 percent CI, 4.92–6.76; p<0.001).

Dementia rates were especially high among participants hospitalized with respiratory, urinary tract, skin, blood and circulatory system, or hospital-acquired infections. There were multiplicative and additive interactions seen by age and APOE-ε genotype.

The present data support the hypothesis that incident dementias are related to infections, and their prevention may play an important role for dementia prevention.