Is Dementia Hereditary?
Medically reviewed by Smita Patel, DO
Dementia is not a specific disease but rather a general term that describes conditions that impair the ability to think, remember, reason, and make decisions. The effects of dementia reduce a person's cognitive level and interfere with their ability to complete daily activities.
While dementia is not a normal part of aging, it is more common in adults over the age of 65 and even higher in people 85 and older. The Centers for Disease Control and Prevention (CDC) states that as of 2014, roughly 5 million adults over the age of 65 had dementia, and by 2060 that number is expected to reach 14 million.
Having a family history of dementia can increase your chances of developing it, but that's not the only contributing factor. Learn about the causes of dementia, types of dementia, and steps to take to prevent it.
Learn More: Dementia and Related Cognitive Disorders
Maskot / Getty Images
Dementia Causes
Dementia is caused by a combination of factors that contribute to the death of brain cells. Cell deterioration, death, and damage to brain cells impair the brain's ability to function properly. Because the brain cells cannot communicate with each other properly, people can experience problems with behavior and thinking. Different regions of the brain like those that play a role in memory, movement, and judgment may be impacted.
Lifestyle factors, including regular exercise, a nutritious eating plan, and avoidance of smoking have been linked to a reduced risk of developing dementia. These behaviors improve vascular health, which can impact brain health.
Lifestyle Factors
Studies have shown that high blood pressure (hypertension), diabetes, and obesity in mid-life are associated with lower brain volumes and impaired cognitive function. These conditions negatively impact vascular health by narrowing arteries, reducing blood flow, and creating inflammation. Better vascular health, particularly during mid-life, has been shown to be protective against cognitive decline. Some of the ways to improve vascular health include regular exercise; eating a nutritious diet rich in fiber, healthy fats, and low in sodium; and not smoking.
Learn More: What Is Vascular Disease?
Environment
The exact role environment plays in the development of dementia is complicated because it's usually not a risk factor that appears in isolation.
In a comprehensive, systematic review, researchers examined 60 studies and the role of the environment. Researchers considered the air quality, toxic heavy metals, other metals, other trace elements, occupational-related exposures, and miscellaneous environmental factors and their role in developing dementia. They found a moderate association between dementia to the following:
Exposure to airborne toxins like smoke, carbon monoxide, and nitrogen oxide
Aluminum in drinking water
Exposure to pesticides (although the evidence was mixed)
Exposure to electric and magnetic fields (power lines)
Researchers admit that this area needs to be investigated further and that the studies they examined varied widely in size and quality. They recommend larger and more robust studies to examine the effects of these environmental risk factors on the development of dementia.
Genetic Risk
Having a family history of dementia increases your risk of developing it. Having a first-degree relative (parent, sibling, or child) with Alzheimer's disease increases the risk of developing it by 10% to 30%.
In addition, having the apolipoprotein E (APOE) gene can increase the risk of developing dementia. But having a family history or genes connected to dementia does not mean you will automatically develop the disease.
Types of Dementia
There are many different types of dementia, and researchers believe that many people have more than one kind.
Vascular Dementia
Vascular dementia is thought to affect about 5% to 10% percent of people who have dementia. Blocked or reduced blood flow to the brain deprives the brain of oxygen and nutrients.
Over time, this can impair storing and retrieving information as well as remembering and thinking. Oftentimes vascular dementia occurs after a stroke or several ministrokes. Symptoms that occur will depend on the severity of blood vessel damage and the area of the brain that it impacts.
Risk factors for vascular dementia are like those that can increase the risk of heart disease and stroke. These include diabetes, high blood pressure, high cholesterol, smoking, sedentary behavior, and poor diet quality.
Frontotemporal Dementia (FTD)
Frontotemporal dementia occurs when there is damage to the neurons in the frontal and temporal lobes of the brain. Estimates suggest that 60% of cases occur in people ages 45–64, but it can also be present in people over the age of 65. Symptoms usually start gradually and progress slowly.
Symptoms include personality changes such as impulsivity and selfish behavior, memory problems, language trouble, slow speech, difficulty finding words, and problems with planning and organizing. Symptoms and the order in which they appear vary from person to person, which can make the condition complicated.
Young-Onset Alzheimer’s Disease
Young-onset dementia is rare and usually occurs between the ages of 30 and 60 years old. It represents less than 10% of the people who have Alzheimer's disease.
Clinical characteristics resemble Alzheimer's disease. Amyloid-positive plaques and tau-positive neurofibrillary tangles are present in the brain. Young-onset Alzheimer's disease has a greater genetic predisposition, and disease progression is faster.
People with young-onset dementia are more likely to have a history of traumatic brain injury but have fewer vascular risk factors, including circulatory problems, diabetes, and obesity.
Lewy Body Dementia
Lewy body dementia is characterized by having deposits of Lewy bodies, a protein known as alpha-synuclein that can affect chemicals in the brain that impact a person's thinking, behavior, mood, and movement. It can be challenging to diagnose because it mimics many other psychological disorders. Lewy body dementia affects a person's balance and movement. It may resemble Parkinson's disease. The progression of the disease can vary widely from one person to another.
Mixed Dementia
Mixed dementia occurs when a person has more than one type of dementia at the same time. People with mixed dementia often have Alzheimer's disease and vascular dementia but can also have a combination of Alzheimer's and another type of dementia.
Prevention
Research suggests approximately a third of Alzheimer’s dementia cases could be attributed to modifiable risk factors such as diabetes, midlife hypertension and obesity, smoking, depression, cognitive inactivity, and low educational attainment.
Although there is no proven prevention regimen, living a healthy lifestyle can help to reduce the risk factors that have been associated with dementia. This includes eating a nutritious diet, not smoking, engaging in regular exercise, and participating in stimulating cognitive activities.
Treatment
Treatment for dementia depends on the cause, symptoms, and severity of the disease. Currently, there is no cure, but there are medications that can help to mitigate symptoms.
Mild cases of Alzheimer's disease are often treated with cholinesterase inhibitors. Examples include:
Razadyne (galantamine)
Exelon (rivastigmine)
Aricept (donepezil)
Namenda (memantine) and Aricept (donepezil) may be used in combination to decrease symptoms and help people to sustain daily functions longer. These medicines work by suppressing glutamate, a chemical in the brain. High levels of glutamate in the brain can lead to cell death.
Immunotherapies such as Leqembi (lecanemab) can help treat cognitive symptoms by reducing amyloid plaques in the brain and are administered intravenously (into a vein). These treatments are intended to slow neurodegeneration and disease progression.
Takeaway
In June 2021, the Food and Drug Administration (FDA) approved Aduhelm for treating Alzheimer's disease. It was the first drug approved for this disease since 2003 and targets amyloid-beta. However, studies showed little or no benefit in slowing cognitive decline. In January 2024, Biogen announced it would discontinue sales and clinical trials for the drug by November 2024.
Learn More: As FDA Narrows Use of New Alzheimer’s Drug, Providers Proceed With Caution
Explainer
Researchers continue to look for alternative treatments that help to slow the progression of the disease and to avoid drug-related side effects. Therapies such as Ayurveda, traditional Chinese practices, meditation, exercise, and nutritional practices (turmeric and ashwagandha), to name a few, have been investigated and explored in their role in treating dementia.
Active compounds in certain foods and herbs may enhance memory and mood and have anti-oxidative benefits. However, their exact role in dementia treatment needs more investigation. Before starting any alternative therapies, it is important to discuss them with your physician.
Learn More: How Alzheimer's Disease Is Treated
Summary
Many risk factors can increase the chances of developing dementia; age, genetic risk, lifestyle, and environment all play a role in contributing to disease development. While there is no current cure, a healthy lifestyle, including regular exercise, a nutritious diet, and cognitive stimulation may reduce your risk.
A Word From Verywell
Having a loved one with dementia doesn't mean you are destined to get it. The genes you inherit are outside of your control, but there are some things you can control to reduce your risk of developing dementia. Regular exercise, a nutritious diet rich in fruits and vegetables, low in saturated fat and sodium, as well as avoidance of smoking, can decrease your risk. Reducing your exposure to environmental pollutants in the air and water and maintaining adequate levels of vitamin D may also help.
Researchers continue to investigate the causes and risk factors for dementia. In doing so, hopefully they are on their way to more conclusive recommendations to all at risk.
Frequently Asked Questions
What are the chances of getting dementia if a parent has it?
Having a first-degree relative increases your chances of developing dementia by 10% to 30%.
What type of dementia is inherited?
Rare genes, referred to as deterministic genes, are thought to cause "familial Alzheimer's," which is a form of early onset Alzheimer's disease. These genes account for 1% or less of Alzheimer's cases.
What is the main cause of dementia?
Dementia isn't caused by one thing alone but rather by a combination of factors, including genes, lifestyle, environment, and other existing medical conditions.
Read the original article on Verywell Health.
