A recent study published in JAMA Network Open has found that hospital-diagnosed infections are associated with an increased risk of dementia. However, the study also revealed that there is no significant association between autoimmune diseases and dementia.
The researchers discovered that infections were associated with a 1.49-fold increase in the rate of dementia. Interestingly, the increase in risk was greater in the short term compared to the long term. On the other hand, autoimmune diseases were associated with only a small 1.04-fold increase in dementia risk, especially after adjusting for infections. This suggests that the association between autoimmune diseases and dementia may be attributed to systemic inflammation, which is associated with both infections and dementia.
The study utilized population-based Danish national registries to conduct a 40-year study from 1978 to 2018. The researchers included Danish residents born between 1928 and 1953 who were alive in Denmark on January 1, 1978, and were aged 65 years or older. Individuals with a prior dementia diagnosis or HIV infections were excluded from the study.
The findings highlight the importance of considering infection-specific processes in the development of dementia. Previous studies on the link between infections and dementia have had limitations, such as focusing on specific infections or pathogens, studying postmortem brains, or having short follow-up periods with selected populations. This study aimed to overcome these limitations by investigating both infections and autoimmune diseases and their potential associations with dementia.
The study revealed that respiratory infections were the most common type of infection, followed by gastrointestinal and urinary infections. For autoimmune diseases, rheumatoid arthritis and polymyalgia rheumatica were the most common. The researchers also found that both infections and autoimmune diseases were associated with increased mortality rates, but the increase was higher for infections.
In summary, this study provides further evidence of the association between infections and dementia. It suggests that infection-specific processes rather than systemic inflammation may play a role in the development of dementia. Further research is needed to better understand the underlying mechanisms and potential preventive strategies.
Source: Janbek J, Laursen TM, Frimodt-Møller N, Magyari M, et al. Hospital-diagnosed infections, autoimmune diseases, and subsequent dementia incidence. JAMA Netw Open. 2023;6(9):e2332635.