Sudden Worsening of Dementia

Samir Kadri
Author: Samir Kadri Medical Reviewer: Morgan Blair Last updated:

Dementia is a progressive disease, meaning symptoms get worse over time. The rate of deterioration varies from person to person.

Various risk factors, such as age and underlying health conditions, affect the rate of progression. However, for some people, dementia can progress suddenly and swiftly.

Can dementia come on suddenly?

Whilst dementia usually worsens gradually over time, it can also come on suddenly. The way dementia will affect a person is challenging to predict. A person might exhibit mild symptoms for a protracted period and then suddenly get worse. On the other hand, they may deteriorate quickly and then level out for a sustained period.

The rate at which dementia progresses can depend on the type of dementia a person has. For example, Alzheimer’s disease is characterized by mild symptoms in the early stages which gradually worsen over time. The same is true of vascular dementia. However, vascular dementia can also develop suddenly, with sufferer’s deteriorating quickly. [1]

Rapidly progressive dementias

Rapidly progressive dementias (RPDs) are neurological disorders that progress quickly over weeks or months after onset of symptoms, and in rare cases over days. [2] RPDs are rare and difficult to diagnose, so it is critical to assess a prospective RPD patient in a hospital setting as quickly as possible. [2] RPDs are often the type of dementia that progress the fastest.

Many RPDs are treatable, and some can be reversed if diagnosed quickly. But for some RPDs, there are no cures, and symptoms worsen quickly.              

Many medical conditions can lead to rapidly progressive dementia, with causes including: [2]

  • Prion disease (autoimmune, neurodegenerative disease)
  • Cancer
  • Infections
  • Vitamin deficiencies
  • Obstructed blood flow to the brain
  • Vitamin B12 deficiency

Other potential causes of sudden deterioration in dementia patients


Exposure to anticholinergic drugs can increase the risk of dementia and worsen the symptoms of dementia. [3] Anticholinergics are used to treat a range of conditions including allergies, mood disorders, gastrointestinal disorders, and bladder disorders.

Routine change

Cognitive impairment and memory loss can be disruptive and disorientating for people with dementia. They often rely on their routines as sources of comfort and stability. A sudden change to the routine can feel stressful, frightening, and can worsen dementia symptoms. [4]

Examples that could cause worsening dementia symptoms include: [4]

  • Hospitalization
  • Moving out of a family home
  • Unfamiliar caregivers


Delirium is a condition that commonly affects people with dementia and causes them to feel suddenly bewildered and distressed.

Delirium is thought to be triggered in dementia patients by a number of medical disturbances including, but not limited to, sudden hospitalization, infection, and surgery. [5]

Studies show that patients with dementia who develop delirium have higher mortality rates. Delirium has been found to accelerate cognitive decline in patients with Alzheimer’s disease. [5]

What to do if dementia symptoms suddenly worsen

The moment you notice someone with dementia experiencing worsening symptoms, you should contact a doctor.

While you may have previously felt comfortable treating a person’s symptoms, a deterioration in condition requires a re-evaluation from a medical professional to see if a new treatment plan is required.

If the dementia patient can communicate how they feel, write down this information. Provide this information to the doctor as it may be helpful in determining the course of treatment.

  1. Website, N. (2021, November 18). Symptoms of dementia.,over%20many%20months%20or%20years.
  2. Geschwind, M. D., Haman, A., & Miller, B. L. (2007). Rapidly progressive dementia. Neurologic clinics, 25(3), 783–vii.
  3. Coupland CAC, Hill T, Dening T, Morriss R, Moore M, Hippisley-Cox J. Anticholinergic Drug Exposure and the Risk of Dementia: A Nested Case-Control Study. JAMA Intern Med.2019;179(8):1084–1093. doi:10.1001/jamainternmed.2019.0677
  4. Porock, D., Clissett, P., Harwood, R. H., & Gladman, J. R. (2015). Disruption, control and coping: responses of and to the person with dementia in hospital. Ageing and society, 35(1), 37–63.
  5. Fong, T. G., Jones, R. N., Shi, P., Marcantonio, E. R., Yap, L., Rudolph, J. L., Yang, F. M., Kiely, D. K., & Inouye, S. K. (2009). Delirium accelerates cognitive decline in Alzheimer disease. Neurology, 72(18), 1570–1575.
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Samir Kadri
Author Samir Kadri Writer

Samir Kadri is a medical writer with a non-profit sector background, committed to raising awareness about mental health.

Published: Apr 4th 2023, Last edited: Nov 10th 2023

Morgan Blair
Medical Reviewer Morgan Blair MA, LPCC

Morgan Blair is a licensed therapist, writer and medical reviewer, holding a master’s degree in clinical mental health counseling from Northwestern University.

Content reviewed by a medical professional. Last reviewed: Apr 4th 2023