What are the Risk Factors and Causes of Alzheimer’s Disease and Other Related Dementias?

Last Updated: September 01, 2018

Risk Factors for Developing Dementia

While heredity plays a role in causing certain forms of dementia, such as Alzheimer’s disease, generally many other factors are also involved. In most cases, dementia is not caused by a person’s behaviors or actions. Instead, most dementia develops as a result of either a biological cause or a physical event in the body. This makes it very difficult to predict who will develop dementia and who will not.

There are risk factors that increase the chance an individual will develop dementia, and the biggest risk factor is age. An individual who is 65 years of age or older has the greatest risk. In fact, according to the Alzheimer’s Association, once a senior has reached 65 years old, the risk for developing Alzheimer’s disease is doubled every 5 years. Above, heredity has also been mentioned as a risk factor. Therefore, it’s important to consider one’s family history of dementia, although environmental factors may also play a role. Mild Cognitive Impairment (MCI) is also a risk factor of developing dementia.


Causes of Dementia

Dementia is the result of damaged nerve cells in the brain, and based on the part of the brain that is damaged, individuals with dementia are affected differently. Simply stated, brain cells that are damaged cannot communicate with other brain cells as they normally would. This can affect the way one thinks, behaves, feels, remembers, and moves. But, what specifically causes dementia?

Neurodegenerative Causes of Dementia

Neurodegeneration is the most common biological cause of dementia and often leads to Alzheimer’s disease. Neurodegeneration is the process where brain cells (neurons) break down and die. These dying brain cells cause a permanent and progressive decrease in mental and physical function over time. Types of dementia that result from neurodegeneration include the following:
Alzheimer’s Disease (AD)
Dementia with Lewy Bodies (DLB)
Frontotemporal Dementias (FTD)
Parkinson’s Disease Dementia (PD)
Huntington’s Disease (HD)

Cerebrovascular Causes of Dementia

Damage to blood vessels in the brain, or cerebrovascular damage, by way of hemorrhage, malformation, or blockage, is a common biological cause of dementia. It is most often caused by strokes, heart disease, and/or hardening of the blood vessels supplying the brain (atherosclerosis). Localized areas of the brain are destroyed (so-called “infarcts”) from not getting enough blood supply (oxygen). The type of dementia that results from cerebrovascular disease is as follows:
Vascular or Multi-Infarct Dementia (VD)

Infection-Related Dementia

Infection can also cause dementia. Viruses, bacteria, and parasites can destroy brain cells and dementia can result in some cases — usually in the later stages of severe infections. Common types of dementia caused by infection include the following:
Creutzfeldt-Jackob Disease (CJD) and other Prion Diseases
Dementia associated with HIV/AIDS

Toxic and Metabolic Causes of Dementia

Dementia can also result from a chemical imbalance in the body caused by a toxin (e.g. drugs), malnutrition, or other biological conditions, such as metabolic disorders. This form of dementia includes the following:
Wernicke-Korsakoff Syndrome (WKS)

Traumatic Causes of Dementia

Serious injuries and concussions to the head and brain are another cause of dementia. This category includes the following dementia:
Traumatic Brain Injury (TBI)


Decrease the Risk of Dementia

While it is not possible to prevent Alzheimer’s disease and other related dementias, there are steps one can take to decrease the chance of developing dementia. Examples include not smoking, getting exercise, stimulating the mind with puzzles and reading, maintaining a nutritious diet, and getting sufficient Vitamin D. Learn more about reducing your risk of dementia here.