People with dementia often become angry because their brains are changing in ways that make it hard to handle emotions, and everyday problems can set them off.
Dementia damages parts of the brain that control feelings and behavior. This leads to outbursts like yelling, hitting, or restlessness, especially in the middle to late stages of the disease.[1][2] A calm person might suddenly get combative due to these brain changes.[1] Anger can show up as verbal aggression, irritability, or even physical actions.[1][4]
One big reason is pain or discomfort that they cannot explain. They might have a headache, infection, or sore joints but struggle to say what hurts, so they lash out instead.[1][7] Hunger, tiredness, or needing the bathroom can also spark anger if basic needs go unmet.[1][7]
Changes in routine or too much noise and confusion in their surroundings often trigger upset. For example, too many people talking or bright lights can overwhelm them.[1][6] Sundowning is a common pattern where anger or agitation ramps up as evening comes, with more restlessness and irritability.[1][6]
Medical issues play a role too. Things like urinary tract infections, side effects from medicines, or even delirium can make someone with dementia suddenly angry.[1][7][8] Depression or anxiety mixed in with dementia adds to mood swings and hostility.[1][3][5]
In vascular dementia, damage to blood vessels in the brain can cause quick anger or emotional ups and downs.[5] Personality shifts happen across types of dementia, turning mild frustration into full outbursts.[9]
Triggers like delusions or feeling threatened also fuel anger. They might see something harmless as scary because their brain misreads it.[1][7]
Sources
https://www.consultant360.com/exclusive/agitation-alzheimer-disease-comprehensive-guide-primary-care
https://assistinghands.com/87/michigan/milford/blog/what-to-do-when-a-dementia-patient-becomes-aggressive/
https://www.scielo.br/j/rbp/a/KjXPQ6sxJD9h8XR4HDYFJrj/
https://pubmed.ncbi.nlm.nih.gov/41439450/
https://www.alzheimersresearchuk.org/dementia-information/types-of-dementia/vascular-dementia/symptoms/
https://ilbrainhealth.org/2025/12/29/coping-with-agitation-aggression-and-sundowning-in-alzheimers-disease-2/
https://www.healthcentral.com/slideshow/can-agitated-outbursts-in-alzheimers-be-prevented
https://www.alzra.org/blog/dementia-vs-delirium/
https://www.dignityhealth.org/conditions-and-treatments/neurology/dementia
