People with dementia face a higher chance of getting infections because the condition affects their body and behavior in ways that make fighting off germs harder. This leads to common problems like urinary tract infections, pneumonia, and skin infections.
One big reason is a weaker immune system. As people age and develop dementia, their body’s defenses slow down. This is called age-associated senescence, which harms both the natural quick-response immunity and the longer-term adaptive immunity that remembers past threats. With a faulty immune system, even everyday germs can cause serious trouble.
Dementia also makes it tough for people to follow basic health rules. They might forget to wash their hands, stay away from sick people, or keep clean during outbreaks. Poor communication adds to the risk. Those with dementia often cannot describe feeling unwell, like pain or fever, so infections go unnoticed until they worsen.
Daily habits suffer too. Many have trouble with personal hygiene, leading to dirty skin or mouth that invites bacteria. Voiding dysfunction, or problems controlling the bladder, raises the odds of urinary tract infections from bacteria like E. coli or Klebsiella. Bedridden patients develop pressure ulcers that let in skin infections from germs such as methicillin-resistant Staphylococcus aureus, or MRSA.
Pneumonia hits hard, happening about ten times more often in dementia care than in healthy older adults living at home. Breathing in germs like Streptococcus pneumoniae or Haemophilus influenzae becomes easier due to swallowing issues or limited movement.
Infections do not just happen more; they speed up dementia. A hospital stay for any infection raises the risk of faster brain decline by 70 percent, with respiratory and urinary infections being the worst offenders. This creates a cycle where dementia invites infections, and infections make dementia worse.
Oral health plays a role as well. Bacteria from gum disease, like P. gingivalis, can travel to the brain, sparking proteins linked to Alzheimer’s. Even without diagnosed dementia, traces of these harmful enzymes appear in brains, hinting at early infection risks from poor dental care.
Viruses matter too. The chickenpox virus, which reactivates as shingles in older age, ties to brain inflammation, vessel damage, and cognitive drop. Vaccines against it show promise in slowing mild impairment that leads to full dementia.
Sources
https://www.droracle.ai/articles/636239/what-organisms-are-dementia-patients-at-risk-for
https://www.sciencealert.com/the-cause-of-alzheimers-may-be-coming-from-within-your-mouth
https://www.alzinfo.org/articles/treatment/shingles-vaccine-could-slow-dementia-progression/
https://pubmed.ncbi.nlm.nih.gov/41434921/?fc=None&ff=20251224103351&v=2.18.0.post22+67771e2
https://www.news-medical.net/news/20251215/New-study-defines-rapidly-progressive-dementia.aspx
