What are the main causes of dementia?

Naomi Carr
Author: Naomi Carr Medical Reviewer: Morgan Blair Last updated:

Dementia is a syndrome that affects the brain, causing issues with several aspects of functioning such as memory and speech. There are several types of dementia, each with slightly different causes and potential risk factors.

What is dementia?

Dementia is a condition related to several neurocognitive disorders, in which parts of the brain become damaged, causing several symptoms relating to cognitive ability, mental state, and physical functioning [1]. Typically, dementia occurs in older adults, over the age of 65, but it can emerge at younger ages and many older adults to not experience dementia symptoms at all [2].

The most common type of dementia is Alzheimer’s disease, which affects over 60% of people with a diagnosis of dementia [2][3]. Other types of dementia include Lewy body dementia, vascular dementia, and frontotemporal dementia.

Each form of dementia can cause slightly different symptoms. Common symptoms of dementia include [1][2]:

  • Memory loss
  • Impaired ability to learn or understand new information
  • Difficulties with speech and language
  • Confusion, especially in new environments
  • Mood and behavior changes
  • Mobility issues

The causes of the different types of dementia can differ from person to person, but research suggests that there are several contributing risk factors to each.

What causes Alzheimer’s disease?

Alzheimer’s disease is caused by a build-up of proteins in the brain called amyloid plaques and tau tangles, which cause increasing damage to the brain as they kill cells and prevent communication between neurons [3][4].

Often, this build-up of proteins occurs in the hippocampus, which is responsible for memory, thus contributing to the emergence of memory deficits, which is commonly the first symptom of Alzheimer’s to be observed [3].

Other risk factors of Alzheimer’s disease include [1][2][3][4]:

  • Age: The risk of Alzheimer’s increases significantly with age. Research suggests that over a third of people over the age of 85 have the condition. This increase in risk may be due to age-related changes in the brain, such as damage or shrinking of certain areas, which exacerbate or contribute to the development of Alzheimer’s.
  • Genetics: A family history of Alzheimer’s dementia can increase the risk of the development of the condition. In some cases, the development of Alzheimer’s is related to an alteration of a specific gene that can be inherited, although this is not always the case.
  • Medical conditions: Various heart conditions can increase the risk of Alzheimer’s, along with strokes, diabetes, and obesity.
  • Unhealthy lifestyle: Research suggests that smoking, poor diet, excessive alcohol use, and not engaging in regular exercise can all increase the risk of Alzheimer’s disease.
  • Lack of brain stimulation: Studies show that Alzheimer’s is more likely in those with low levels of education, limited social engagement, and a lack of cognitive activity.

What causes Lewy body dementia?

Lewy body dementia is caused by a build-up of proteins in the brain called Lewy bodies, which contributes to a reduced level of acetylcholine in certain parts of the brain. This causes the development of symptoms such as hallucinations and delusions that are common with Lewy body dementia but less so with other types [5].

Risk factors of Lewy body dementia are not specifically known. It often presents with similar symptoms to Alzheimer’s or Parkinson’s dementia, causing challenges in differentiating the exact causes or individual risk factors [6].

As such, further research is required to determine the exact risk factors of Lewy body, but it is believed that age and genetics may also be contributing risk factors, as is the case with other types of dementia, although this is currently unclear [5][6].

What causes vascular dementia?

Vascular dementia is caused by a lack of blood to the brain, therefore reducing available oxygen in the brain and resulting in cell damage and death. This could occur due to a stroke or narrowed blood vessels in the brain [1][7].

Risk factors include [7]:

  • Overall health: The risk of vascular dementia is increased by factors that may cause a stroke or similar issues that reduce blood flow to the brain. This includes poor diet, lack of exercise, smoking, excessive alcohol use, heart problems, diabetes, high cholesterol, and obesity.
  • Genetics: While there is no clear heritability of vascular dementia itself, there is a potential for the above health conditions to be inherited if there is a family history.
  • Age: The risk of many of the above health conditions, and of the development of dementia, is increased as people age.

What causes frontotemporal dementia?

Frontotemporal dementia is caused by damage to either or both the frontal and temporal lobes, causing behavior and mood changes or speech and language impairment [8].

Similar to Alzheimer’s, this damage is caused by a build-up of tau proteins, resulting in a loss of neurons and cell death. However, as this damage occurs in a different part of the brain, the symptoms of frontotemporal dementia differ significantly from the symptoms of Alzheimer’s [9].

Risk factors include [8][9]:

  • Genetics: Around a third of cases of frontotemporal dementia are believed to be inherited, as research shows that altered genes can lead to the development of the condition, so a family history of this type of dementia can greatly increase the risk.
  • General health: As with other types of dementia, unhealthy lifestyle choices or certain medical conditions can increase the risk of frontotemporal dementia, including smoking, alcohol use, and poor diet. Other health conditions, such as cardiac issues, diabetes, and traumatic brain injury can all lead to frontotemporal dementia.

Unlike the other types of dementia, frontotemporal dementia does not carry the same age-related risks, as this type of dementia typically emerges between the ages of 45-65 [9].

FAQs about dementia causes

Does alcoholism cause dementia?

Studies indicate that excessive alcohol use can greatly increase the risk of dementia. This risk can be mitigated or managed by reducing alcohol consumption and adopting healthy lifestyle choices [2][3][7].

Does melatonin cause dementia?

Melatonin is a natural chemical that helps us maintain our sleep-wake cycle. As we age, levels of melatonin tend to decrease, so many older adults use melatonin supplements to help with sleep [10].

There is no evidence to suggest that using melatonin supplements will increase the risk of dementia and short-term use has been found to cause no harm, although research into the effects of long-term use is limited so further studies are required [11].

There is research to suggest that the use of melatonin may actually improve cognitive functioning in those with Alzheimer’s disease, along with improving the quality of sleep [10][12].

Does Benadryl cause dementia?

Recent research has found that there is a link between the long-term use of Benadryl and an increased risk of dementia, potentially due to the effect that Benadryl has on acetylcholine levels, thus contributing to cognitive decline and memory loss [13][14].

Short-term use of Benadryl is considered to be safe [14].

Do statins cause dementia?

Some studies indicate that the use of statins can contribute to a reduced risk of dementia [15][16]. However, the results of these studies are not conclusive, so further research is needed.

As such, statins should not be taken for any purpose other than to treat heart conditions and should be taken only as prescribed [15].

Can a stroke cause dementia?

Stroke is a common cause of brain damage that causes dementia, especially vascular dementia. Stroke can lead to cell death and therefore greatly increasing the risk for the onset of dementia symptoms [1][2].

  1. Centers for Disease Control and Prevention. (Reviewed 2019). About Dementia. CDC. Retrieved from https://www.cdc.gov/aging/dementia/index.html
  2. World Health Organization. (2022). Dementia. WHO. Retrieved from https://www.who.int/news-room/fact-sheets/detail/dementia
  3. Alzheimer’s Association. (n.d). What is Dementia? Alzheimer’s Association. Retrieved from https://www.alz.org/alzheimers-dementia/what-is-dementia
  4. National Institute on Aging. (Reviewed 2019). What Causes Alzheimer’s Disease? NIH. Retrieved from https://www.nia.nih.gov/health/what-causes-alzheimers-disease
  5. Haider, A., Spurling, B.C., & Sánchez-Manso, J.C. (2022). Lewy Body Dementia. In StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK482441/
  6. Alzheimer’s Association. (n.d). Dementia with Lew Bodies. Alzheimer’s Association. Retrieved from https://www.alz.org/alzheimers-dementia/what-is-dementia/types-of-dementia/dementia-with-lewy-bodies
  7. National Health Service. (Reviewed 2020). Causes – Vascular Dementia. NHS. Retrieved from https://www.nhs.uk/conditions/vascular-dementia/causes/
  8. National Health Service. (Reviewed 2020). Overview – Frontotemporal Dementia. NHS. Retrieved from https://www.nhs.uk/conditions/frontotemporal-dementia/
  9. National Institute on Aging. (Reviewed 2021). What are Frontotemporal Disorders? Causes, Symptoms, and Treatment. NIH. Retrieved from https://www.nia.nih.gov/health/what-are-frontotemporal-disorders
  10. Cardinali, D.P., Furio, A.M., & Brusco, L.I. (2010). Clinical Aspects of Melatonin Intervention in Alzheimer’s Disease Progression. Current Neuropharmacology, 8(3), 218–227. Retrieved from https://doi.org/10.2174/157015910792246209
  11. Andersen, L.P., Gögenur, I., Rosenberg, J., & Reiter, R.J. (2016). The Safety of Melatonin in Humans. Clinical Drug Investigation, 36(3), 169–175. Retrieved from https://doi.org/10.1007/s40261-015-0368-5
  12. Sumsuzzman, D.M., Choi, J., Jin, Y., & Hong, Y. (2021). Neurocognitive Effects of Melatonin Treatment in Healthy Adults and Individuals with Alzheimer’s Disease and Insomnia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Neuroscience and Biobehavioral Reviews, 127, 459–473. Retrieved from https://doi.org/10.1016/j.neubiorev.2021.04.034
  13. Wong, H.C.G. (2015). Long-Term Use of Diphenhydramine. CMAJ: Canadian Medical Association Journal, 187(14), 1078. Retrieved from https://doi.org/10.1503/cmaj.1150066
  14. Gray, S.L., Anderson, M.L., Dublin, S., Hanlon, J.T., Hubbard, R., Walker, R., Yu, O., Crane, P.K., & Larson, E.B. (2015). Cumulative Use of Strong Anticholinergics and Incident Dementia: A Prospective Cohort Study. JAMA Internal Medicine, 175(3), 401–407. Retrieved from https://doi.org/10.1001/jamainternmed.2014.7663
  15. Poly, T.N., Islam, M.M., Walther, B.A., Yang, H-C., Wu, C-C., Lin, M.C., & Li, Y-C. (2020). Association between Use of Statin and Risk of Dementia: A Meta-Analysis of Observational Studies. Neuroepidemiology, 54(3), 214-226. Retrieved from https://doi.org/10.1159/000503105
  16. Zhang, X., Wen, J., & Zhang, Z. (2018). Statins Use and Risk of Dementia: A Dose-Response Meta Analysis. Medicine, 97(30), e11304. Retrieved from https://doi.org/10.1097/MD.0000000000011304
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Naomi Carr
Author Naomi Carr Writer

Naomi Carr is a writer with a background in English Literature from Oxford Brookes University.

Published: Mar 30th 2023, Last edited: Sep 22nd 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: Mar 30th 2023