How common is dementia, and is dementia hereditary? According to the World Health Organization (WHO), over 55 million people from all around the world live with dementia. There are over 10 million new cases of dementia reported every year, that’s why many scientists and individuals wonder if there is a genetic link and conduct research to figure out, is dementia hereditary.
Dementia is a neurodegenerative disease that results from damage to brain cells, which in turn equates to a decline in the patient’s cognitive abilities. Alzheimer’s disease (AD) is the most common type of dementia, accounting for ⅔ of dementia cases in people ages 65 and older.
Dementia impacts each patient uniquely, depending on the underlying causes, other health problems, and the patient’s state of cognitive function before the diagnosis. That’s why scientists often have conflicting research results when it comes to answering the question “is dementia hereditary”.
Whatever the underlying reason for the disease’s onset is, the varying types of dementia do share similar symptoms.
Patients with dementia grapple with various cognitive impairments such as memory loss, confusion, poor understanding, hampered communication skills, language impairments, inability to perform old skills, impaired reasoning, and/ or inability to recognize objects. Because of this disease’s impact on the patient’s quality of life, many people are alarmed about their potential genetic risk of dementia, and wish to ascertain is dementia hereditary. Learn more about the genetic components of dementia below.
The Complex Underpinnings: Is Dementia Hereditary?
Most literature says that dementia is not strictly hereditary but there could be genetic variables involved. This concept could be very confusing for the average layman with no medical background. It’s not surprising that the literature on this topic is diverse because dementia symptoms are unique based on each individual case. Moreover, every person has their own set of genetic codes that make up millions of variations. At the same time, no scientist has been able to successfully map out the brain and all of its neural connections.
Keep in mind that different people’s brains connect and work in various ways, so researchers can’t just map one individual brain and call their research complete. For dementia studies, a lot of evidence points out that it is usually a combination of genetics and environmental factors that precipitate the onset of symptoms. For example, on the “Is dementia hereditary?” page of Alzheimer’s Society, they shared that 99 in 100 cases of AD are not inherited.
The most crucial risk factor for Alzheimer’s disease is age, with people in their late 70s or 80s manifesting symptoms. Notably, the risk of onset doubles every five years after age 65. Hence, having an older relative with late-onset AD doesn’t automatically mean you will be afflicted by the same disease, nor will it increase your chances of developing Alzheimer’s later in life compared to the rest of the population.
In fact, in the case of twins, if one twin is diagnosed with Alzheimer’s disease, the other twin only has a 40 to 50% chance of experiencing the same symptoms. This means dementia is not purely a hereditary disease, but having certain genes may increase a person’s risk of developing dementia.
Environmental factors such as exposure to stress or substance abuse could also play a significant role in causing a person to get dementia. However, early-onset Alzheimer’s is a different story as it is seen as familial in nature and could be more linked with genetics (more on this later).
In other words, if you were wondering, is dementia hereditary, certain types such as early-onset Alzheimer’s are more likely to be hereditary and potentially run in families.
Genetic Risk Factors Depend on the Type of Dementia
Your genes control the function of the cells in your body. This means genes could determine physical traits of yours, such as your eye color and height, temperament, and even disease risks. Some genes present in your unique DNA could make you more likely to develop certain diseases. For example, a stroke may make you more susceptible to vascular dementia or dementia due to damage in the brain because of blood flow restrictions. These same genes could also make you more likely to suffer from early-onset AD.
According to experts, “dementia” is an umbrella term used to describe clinical manifestations of progressive cognitive decline. This means once the symptoms occur, there is a persistent and continuous waning of cognitive abilities that are irreversible. The subtypes of dementia are classified according to the cause.
Below are four of the most common subtypes of dementia:
Alzheimer’s Disease (AD)
Alzheimer’s disease is the most common type of dementia, consuming 60 to 80% of dementia cases. This disease is triggered by changes in the brain structure due to plaque formation, usually occurring at later age. The latter occurs as a result of unusual and tangled protein buildup. Those wondering is dementia hereditary would feel relieved that late-onset AD is typically not an inherited condition.
However, there are few familial cases of Alzheimer’s where the disease symptom appears early, usually between 30 to 65 years of age. This early-onset form of Alzheimer’s, taking up a small number of cases (less than 5%), could be hereditary. Childhood dementia, a rare form of dementia manifesting in children younger than 18 years old, is also a cause for concern. For those that manifest symptoms early in life, research suggests that there could be a strong genetic link and the disease could be caused by genetic mutations.
Mutations in three genes have been identified as being responsible for this AD variant. Unfortunately, one single copy of the mutated gene is enough for a person to develop early-onset familial Alzheimer’s disease. Thus, anyone who develops early-onset Alzheimer’s may have a type of disease that could be passed on from generation to generation. In general, the earlier an individual is diagnosed with AD, the more likely that is due to faulty inherited gene codes.
Vascular dementia
This onset of this disease occurs when brain blood vessels get damaged due to poor flow of oxygenated blood, such as what happens with a stroke. Is dementia hereditary for this subtype? Vascular dementia is not inherited, BUT the underlying health problem associated with it could be passed on from generation to generation.
The genes that increase the risk of vascular dementia are related to the same genes that increase the risk of hypertension, diabetes, and stroke. Having a healthy lifestyle with a good diet and a regular exercise program could help prevent vascular dementia.
Frontotemporal dementia (FTD)
This usually occurs in people below 60, and not many people are diagnosed with FTD compared to AD and vascular dementia. However, for people with early symptoms, FTD is the common culprit. Bruce Willis is a famous actor with dementia, and he lent a face to provide more awareness for this disease when he was recently diagnosed.
Is dementia hereditary for this category? Notably, most cases of FTD are not inherited, but 40% of those diagnosed may have one close relative with this health problem. Thus, this could be alarming for families who have older relatives with FTD as it means they have a higher risk of developing the disease. Remember, risk only speaks of the chance or likelihood that the condition will occur but it doesn’t necessarily mean that it will happen for sure.
Lewy body dementia (LBD)
This condition occurs when atypical proteins called Lewy bodies accumulate in the brain.
The presence of these proteins is the same hallmark for Parkinson’s disease. Initially, patients with LBD were misdiagnosed with Alzheimer’s disease or Parkinson’s disease. But as LBD patients became worse, it was apparent that it was a different disease altogether. As the disease became worse, patients eventually became disabled, and some even died within eight years of the initial diagnosis.
Because this type of dementia was newly acknowledged as a separate disease only two decades ago, there’s not as much body research and substantial data covering this area. There is conflicting research on LBD. Some studies assert that LBD cases are not inherited. That’s why it is rare to see family members having been diagnosed with this condition. Meanwhile, other scientists state that five genes have been recently discovered to play a role in LBD. Hence, a very small portion of LBD cases may be inherited.
Reducing Your Risk of Developing Dementia
In most cases, dementia will not be inherited by family members, because the majority of dementia cases fall under late-onset Alzheimer’s disease where age is the primary risk factor. Only the rare types of dementia show a strong genetic link, but these cases only comprise a minute portion of overall dementia cases. However, it is vital not to ignore possible genetic risks, especially if you have family members with rare types of dementia.
Fortunately, there are new horizons for prevention and treatment which include genetic studies that could lend insight into an individual’s unique gene profile. It is also crucial to note that early diagnosis and treatment could help slow down dementia’s progression. Moreover, taking preventive steps will help tremendously in outcomes. For example, taking a CircleDNA test from the comforts of home will provide you with a well-spring of information and DNA insights about your health, through extensive health reports based on whole-genome sequencing tests.
Apart from providing you with ancestry information, disease risk, genetic nutrition guidelines and genetic personality traits, CircleDNA findings also come with brain health reports, explaining potential risk for everything from Alzheimer’s, Frontotemporal Dementia, Bipolar Disorder, Parkinson’s Disease, and more. Living a healthy lifestyle with balanced nutrition suited to your DNA, minimal stress, avoidance of drugs and smoking, low levels of alcohol intake, and regular exercise could help prevent dementia.
References:
- Dementia (WHO) https://www.who.int/news-room/fact-sheets/detail/dementia
- Alzheimer Disease (Anil Kuhmar et.al.) https://www.ncbi.nlm.nih.gov/books/NBK499922/
- Is dementia hereditary? (Alzheimer’s Society) https://www.alzheimers.org.uk/about-dementia/risk-factors-and-prevention/is-dementia-hereditary
- Risk factors for dementia (Catriona McCullagh et.al.) https://citeseerx.ist.psu.edu/viewdoc/downlohttps://www.alzheimers.org.uk/about-dementia/risk-factors-and-prevention/is-dementia-hereditary
- Dementia (Sylvia Duong et.al.) https://www.mayoclinic.org/diseases-conditions/alzheimers-disease/in-depth/alzheimers-genes/art-20046552
- Alzheimer’s genes: Are you at risk? (Mayo Clinic) https://www.mayoclinic.org/diseases-conditions/alzheimers-disease/in-depth/alzheimers-genes/art-20046552
- Bruce Willis has frontotemporal dementia: What is ftd? (AP News) https://apnews.com/article/what-is-frontotemporal-dementia-bruce-willis-fbfdbfca4793bb65ef3f38f31e31bd68
- Caring for loved ones with frontotemporal degeneration (Bobby Boland) https://www.bannerhealth.com/healthcareblog/teach-me/caring-for-loved-ones-with-frontotemporal-degeneration
- What is Lewy Body Dementia (Alzheimers.gov) https://www.alzheimers.gov/alzheimers-dementias/lewy-body-dementia
- Genetic study of Lewy body dementia supports ties to Alzheimer’s and Parkinson’s diseases (NIH) https://www.nih.gov/news-events/news-releases/genetic-study-lewy-body-dementia-supports-ties-alzheimers-parkinsons-diseases
