Alzheimer’s Disease (Deming, 2019) – Is dementia genetic?

Old woman bw alzheimers

Nebula Genomics DNA Report for Dementia

Is dementia genetic? We created a DNA report based on a study that attempted to answer this question. Below you can see a SAMPLE DNA report. To get your personalized DNA report, purchase our Whole Genome Sequencing!

Is dementia genetic? Sample report from Nebula Genomics
Is dementia genetic? Sample report variants from Nebula Genomics
To learn more about how Nebula Genomics reports genetic variants in the table above, check out the Nebula Research Library Tutorial!
This information has been updated to reflect recent scientific research as of April 2021.

What is Dementia? (Part 1 of Is dementia genetic?)

Dementia is a pattern of symptoms of different diseases, the main feature of which is a deterioration of several mental and cognitive abilities. It can be caused by various degenerative and non-degenerative diseases of the brain. 

The symptoms of dementia include a combination of loss of cognitive, emotional, and social skills. Most commonly affected are short-term memory, thinking, speech, and motor skills; some forms also involve personality changes. A characteristic feature of dementia is the loss of thinking skills that have already been acquired during daily life.

Today, the causes of some of the conditions have been discovered, but for many forms, there is still no clear, undisputed common cause of dementia. Genetics is known to play a role to various degrees depending on the form of dementia. A few forms are reversible; for some other forms, therapeutic interventions are possible to a limited extent, but these can only delay the onset of certain symptoms. Alzheimer’s disease is the most common form.

Dementia leads to memory loss and other problems
Dementia is characterized by memory loss, cognitive problems, and loss of emotional and social skills. Pixabay.com

Is Dementia Genetic?

The condition is caused by damage to or loss of nerve or brain cells and their connections in certain parts of the brain. The main risk factor for dementia is old age. More women suffer from dementia than men, most often contributed to women’s longer life expectancy. Depression is considered a risk factor, occurring more frequently in the early stages of dementia and can even precede dementia. 

The role of genetics in dementia varies with regards to the type. For example, the role of genes in frontotemporal dementia seems much greater than in the vascular form of the disease. 

In Alzheimer’s, four risk genes have been positively associated with the onset of the disease.

A genetic variant in the gene for ApoE has been identified as a risk factor for the development of Alzheimer’s disease. It was the first gene with mutations found to cause an inherited form of Alzheimer’s and remains as the gene associated with the highest risk of developing dementia. Researchers estimate that between 40-65% of people diagnosed with Alzheimer’s have the APOE-e4 gene. APOE-e4 is one of three common types of the APOE gene; the others are APOE-e2 and APOE-e3. A person with two inherited types of APOE-e4 is at a higher risk of developing Alzheimer’s than an individual inheriting one form, who is at higher risk than someone who didn’t inherit any. 

In addition, genetic mutations in three different genes called presenilin-1 and -2 and amyloid precursor protein (APP) also increase the risk of Alzheimer’s. These mutations are thought to cause only a small percentage of Alzheimer’s cases (1 percent or less). In Alzheimer’s patients, an amyloid precursor protein form called beta-amyloid 42 accumulates in toxic levels in the brain, producing clumps of plaques that add up between neurons, disrupting cell function. Ongoing research suggests that the genes mentioned above affect the production of various forms of beta-amyloid. 

Further risk factors are cardiovascular factors, such as hypertension, high homocysteine levels, high blood pressure, renal insufficiency, obesity, and diabetes mellitus. Some environmental factors such as exposure to toxic chemicals (which could lead to mutated genes) could increase the risk of developing the condition.

You can learn more about your genetic makeup by checking out these accompanying reports on Alzheimer’s.

Current Research on Dementia [Updated April 2021]

A study published in Molecular Neurobiology journal titled “Relationship Between Genetic Variants of ACAT1 and APOE with the Susceptibility to Dementia (SADEM Study)” evaluates the relationship between ACAT1 and APOE genetic variants and how these genes can increase an individual’s chance of developing the condition. 

The researchers examined four ACAT1 polymorphisms (rs2247071, rs2862616, rs3753526, rs1044925) and two in the APOE gene (rs7412, rs429358). The result shows one protective haplotype associated with developing the disease. According to the journal, the results suggest that the ACAT1 and the APOE genes play an important role in susceptibility.

Another study, titled “Genetic Testing in Dementia–A Medical Genetics Perspective,” posted by Willie Online library in the International Journal of Geriatric Psychiatry, 2021 examined whether genetic testing in the diagnostic pathway in some patients with dementia can help to reduce the time taken to identify the cause of the illness. 

The researchers examined studies involving genetics posted in PubMed up to March 2020. They also reviewed patient files to create composite cases.

According to the journal, the result shows that families with a family history of dementia who tend to have individuals develop the disorder at a younger age, especially before age 65, tend to harbor a genetic component that influences the development of the condition.

Thus, genetic testing can help to identify the cause of the condition. It also helps identify younger people who are susceptible to the disease even before they begin to feel the symptoms.

For the most up to date research, you should check out resources provided on the the National Institute on Aging website.

Prevention (Part 4 of Is dementia genetic?)

Today’s most promising strategies are primarily considered to be control of cardiovascular risk factors, physical activity, control of body weight, avoiding harmful alcohol use, and early treatment of depression. Since tobacco smoking is also a possible risk factor, discontinuing cigarette consumption also contributes to dementia prevention. A recent study confirms that, above all, sport and healthy lifestyle choices (and thus the avoidance of cardiac risk factors) can prevent/reduce the risk of developing the condition.

Forms (Part 5 of Is dementia genetic?)

In part to reduce the stigma of those with the disease, the new edition of DSM-5 of the US Diagnostic and Statistical Manual of Mental Disorders, which was published in 2013, no longer uses the term dementia but refers to it as neurocognitive disorders (NCD) and largely includes all acquired brain disorders, with the exception of cognitive impairment in psychosis or schizophrenia and cognitive disorders in developmental brain disorders.

Numerous forms are distinguished. Alzheimer’s dementia is the most common form, probably accounting for more than 60% of all cases. It usually does not occur until after the age of 60. The estimated proportion of the general population aged 60 and over with the condition at a given time is between 5-8%.

In contrast, mild cognitive impairment (MCI), which has not been considered in the DSM, is included as well as delirium, the latter as a separate category. 

Other characteristics involve lower functioning of the brain
Progressive disease include memory loss, cognitive difficulties, and behavioral changes. Pikist.com

Common types of dementia include:

Progressive forms of the disease

Other disorders

Dementia-causing reversible conditions

  • Infections 
  • Immune disorders
  • Metabolic problems 
  • Endocrine abnormalities
  • Nutritional insufficiencies
  • Medication side-effects
  • Subdural hematomas
  • Poisoning
  • Brain tumors
  • Anoxia
  • Normal-pressure hydrocephalus

Epidemiology (Part 6 of Is dementia genetic?)

According to the World Health Organization (WHO), around 50 million people with dementia worldwide, and there are nearly 10 million new cases of dementia every year.

The world’s most common form (as of 2020) is Alzheimer’s disease, with a share of about 60%. The second most common form, with figures between 10 and 20%, is the vascular form of the disease. A diagnosis is often made only based on the symptoms.

Characteristics and Symptoms (Part 7 of Is dementia genetic?)

Some initial symptoms can hardly be distinguished from depression, such as loss of interest and initiative, irritability, and depressive moods. The main symptom that classified dementia is memory impairment, especially short-term memory. Other functions that are often progressively lost include language skills, visual perception, problem-solving, self-management, and the ability to focus and pay attention. Some people cannot control their emotions, and their personalities may change. 

According to Mayo Clinic, symptoms of dementia include both cognitive and psychological changes:

Cognitive changes:

  • Memory loss
  • Difficulty communicating or finding words
  • Difficulty with visual and spatial abilities, such as getting lost while driving
  • Difficulty reasoning or with problem-solving
  • Difficulty handling complicated tasks
  • Struggle with organizing and planning
  • Problems with coordination and motor functions
  • Confusion and disorientation

Psychological changes:

  • Changes in personality
  • Depression
  • Anxiety
  • Inappropriate behavior
  • Paranoia
  • Agitation
  • Hallucinations

While dementia is most common in older adults, it is not a normal part of aging. If you or a  loved one has memory problems or other dementia symptoms, it’s important to see a doctor and determine the underlying cause.

Symptoms can be divided into three stages: Early, middle, and late.

Early-stage

This early onset stage is often missed due to the mildness and gradual nature of symptoms:

  • Forgetfulness
  • Losing track of time
  • Becoming lost in familiar places

Middle stage

Signs and symptoms become more pronounced and often noticeable. 

  • Gradually forgetting recent events and people’s names
  • Getting lost at home
  • Progressive difficulty with communication
  • Needing assistance with personal care
  • Experiencing behavior changes, including wandering and pacing up and down

Late

The late stage is characterized by complete dependence and inactivity. Memory disorders are serious, and the physical signs become distinct.

  • Becoming oblivious of time and place
  • Experiencing difficulty recognizing relatives and friends
  • An increasing need for assisted self-help
  • Walking with difficulty 
  • Behavioral changes that may turn aggressive

Diagnosis (Part 8 of Is dementia genetic?)

The patient’s medical and family history provides important information on the diagnosis. Often, doctors will consult with family members who may have noticed the symptoms. Physicians will first assess whether an underlying treatable condition is causing cognitive problems, such as abnormal thyroid function or a vitamin deficiency, most often through blood tests. 

If dementia is suspected, brain scans may confirm the diagnosis. Scans such as computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) can identify strokes, tumors, and risk factors.

Some dementias, such as inherited Alzheimer’s, are caused by known faulty gene defects. Genetic tests and speaking with a genetic counselor can help assess a person’s risk. Some at-home tests for dementia include:

  • 23andMe – Health + Ancestry Service
  • GeneDx – wide variety of clinical genomic tests
  • Invitae – diagnostics, proactive health, and reproductive health
  • Myriad Genetics – diagnostics, reproductive tests, and precision medicine tests

Treatment (Part 9 of Is dementia genetic?)

Treatment for dementia depends on its cause. In the case of most progressive forms, including the onset of Alzheimer’s, there are no cures or treatments known to slow or stop its progression. In some cases, symptoms can temporarily be improved. Early diagnosis and providing information and long-term support to caregivers is necessary to promote early and optimal management.

There are multiple medications used to treat different types of Alzheimer’s symptoms. Early to moderate stage types treats memory, thinking, language, and other thought process problems. Severe stage medication is more effective at improving these issues. Sometimes, the two drug types are taken together.

A caretaker and a person with dementia
Early detection and support for caretakers is important to the ultimate treatment of dementia. Pxhere

The onset of dementia affects people differently. Various forms of non-drug interventions have been developed to favorably influence disease signs, improve the well-being of those affected and/or maintain abilities for as long as possible. These interventions can be carried out in occupational therapy or coping tips, for example.

Numerous new treatments are in various stages of clinical trials. 

If you liked this article, check out our other reports in the Nebula Research Library!

You may be especially interested in these articles on conditions that may accompany Alzheimer’s like schizophrenia and bipolar disorder.