Pneumonia happens often in people with dementia because their brains struggle to control basic body functions that keep lungs healthy. This leads to infections that build up quietly and spread fast.
One big reason is trouble swallowing. Dementia affects the nerves that help move food and saliva down the right way. Instead, bits of food or liquids slip into the lungs, causing aspiration pneumonia. This type is common with mixed germs from the mouth, including hard-to-fight ones like Streptococcus pneumoniae or Haemophilus influenzae. Poor teeth or dry mouth make it worse by letting more bad germs grow in the mouth.
People with dementia also forget to cough or clear their throats when needed. Their weakened immune systems from old age cannot fight germs as well. They might not notice early signs of sickness or tell others, so infections grow before doctors spot them.
Living in groups like nursing homes raises the risk too. Germs spread easily in close spaces, and devices like feeding tubes or catheters add spots for bacteria to hide. Other health issues common with dementia, such as weak lungs or diabetes, pile on the danger.
Rates show the problem clearly. Dementia patients get pneumonia at a pace of one case every 1000 days of care. That is ten times higher than older people living at home.
Sources:
https://www.droracle.ai/articles/636239/what-organisms-are-dementia-patients-at-risk-for
https://pmc.ncbi.nlm.nih.gov/articles/PMC12745565/
https://doralhw.org/pneumonia-risk-10-factors-that-make-you-vulnerable-and-simple-steps-to-protect-your-lungs/
https://www.rheumatologyadvisor.com/news/physical-frailty-depression-linked-to-increased-dementia-risk/
https://www.consultant360.com/exclusive/pulmonology/pneumonia/bacterial-pneumonia-and-oral-candidiasis-are-strongly-related
https://nagasaki-u.repo.nii.ac.jp/record/2003537/files/R29_722.pdf
