Hospitalization due to infection increases the risk for incident dementia by 70%, especially following urinary tract, blood and circulatory system, and hospital-acquired infections, according to the findings of a large observational study published in JAMA Network Open.
By 2050, there will be a projected 152 million prevalent cases of dementia worldwide. Despite its high prevalence, only half of AD cases are attributable to modifiable factors; other factors associated with dementia risk are not completely understood. Systemic infections are believed to be factors of incident dementia and could potentially serve as targets for prevention and screening, according to researchers.
In the United States, researchers conducted a community-based, prospective, cohort study, the Atherosclerosis Risk in Communities (ARIC) study, which enrolled participants between 1987 and 1989 and followed up through December 2017 to December 2019. They analyzed the relationship between hospitalization due to infection and incident dementia across 15,688 participants who were dementia-free at baseline.
Of these 15,688 dementia-free participants, 5999 (38.2%) were hospitalized for infection during the study. Onset of dementia occurred in 2975 (19.0%) participants.
Researchers calculated incidence rates for dementia among the exposed and unexposed participants. They determined that 23.6 events per 1000 person-years occurred among the participants hospitalized due to infection, whereas 5.7 events per 1000 person-years occurred among the unexposed individuals.
Patients hospitalized due to infection were significantly more likely to develop incident dementia compared with unexposed individuals (unadjusted hazard ratio [HR], 2.02; 95% CI, 1.88-2.18; P <.001; adjusted HR [aHR], 1.70; 95% CI, 1.55-1.86; P <.001). This risk increased even more significantly between 3 and 20 years following exposure (aHR, 5.77; 95% CI, 4.92-6.76; P <.001).
Rates of incident dementia increased among individuals hospitalized due to respiratory, skin, urinary tract, blood and circulatory system, or hospital-acquired infections. Additionally, when the researchers analyzed incident dementia according to genotype and age, patients who were not carriers of APOE-ε4 alleles and those of advanced age were more likely to develop dementia after hospitalization.
Overall, the researchers found hospitalization with infection was associated with a greater risk of developing dementia. They noted that their findings “[H]ighlight that the risk of dementia differs by infection type, suggesting that specific pathophysiological aspects of an infection might affect dementia risk.”
“These findings highlight the importance of infection prevention broadly and the need for identifying novel approaches to prevent deleterious effects of infections, including cognitive sequelae, throughout the lifetime,” they concluded.
Study limitations included the observational design increasing the potential for unmeasured or residual confounding variables, inability to assess for known risk factors increasing dementia risk, potential selection bias caused by loss to follow-up. Moreover, there was a lack of assessment of infections in these individuals prior to study initiation, and the lack of assessment of treatment approaches that may have influenced the results.
Bohn B, Lutsey PL, Misialek JR, et al. Incidence of dementia following hospitalization with infection among adults in the Atherosclerosis Risk in Communities (ARIC) study cohort. JAMA Netw Open. Published online January 9, 2023. doi:10.1001/jamanetworkopen.2022.50126