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!

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 and nervous system. 

Symptoms 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 the disease is the loss of thinking skills that have already been acquired during the course of life.

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

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

Is Dementia Genetic?

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

The role of genetics varies with regards to the type of dementia. For example, the role of genes in frontotemporal dementia (FTD) seems to be much greater than in vascular dementia. 

In Alzheimer’s, four 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 genetic mutations found to cause an inherited type 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 forms of the APOE gene; the others are APOE-e2 and APOE-e3. A person with two inherited forms 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. Having this risk gene may also increase risk for vascular dementia, but this association is not as strong as with Alzheimer’s.

In addition, 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 rare cases (1 percent or less). All of these genes affect processing or production of beta-amyloid, the protein fragment that is the main component of plaques. Beta-amyloid is a prime suspect in decline and death of brain cells. 

Further risk factors are cardiovascular factors, such as hypertension, high homocysteine levels, renal insufficiency, obesity and diabetes mellitus

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

Prevention (Part 3 of Is dementia genetic?)

The most promising strategies today 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 for dementia, discontinuing cigarette consumption also contributes to dementia prevention. A recent study confirms that above all sport and a healthy lifestyle (and thus the avoidance of cardiac risk factors) can prevent dementia.

Forms (Part 4 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 brain developmental disorders. 

Numerous types of dementia are distinguished. Alzheimer’s is the most common form, probably accounting for more than 60% of all cases. It usually does not occur until after the age of 65, at which time the chance of developing the disease is much higher. The estimated proportion of the general population aged 60 and over with dementia 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 dementias include memory loss, cognitive difficulties, and behavioral changes.

Common types of dementia include:

Progressive forms of the disease

Other disorders linked to dementia

  • Huntington’s disease
  • Traumatic brain injury (TBI)
  • Creutzfeldt-Jakob disease
  • Parkinson’s disease

Similar conditions that can be reversed

  • Infections and immune disorders
  • Metabolic problems and endocrine abnormalities
  • Nutritional deficiencies
  • Medication side effects
  • Subdural hematomas
  • Poisoning
  • Brain tumors
  • Anoxia
  • Normal-pressure hydrocephalus

Epidemiology (Part 5 of Is dementia genetic?)

According to the World Health Organization (WHO), around 50 million people have 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 of dementia, with figures between 10 and 20%, is vascular dementia. A diagnosis is often made only on the basis of the symptoms.

Characteristics and Symptoms (Part 6 of Is dementia genetic?)

Some initial symptoms can hardly be distinguished from those of depression, such as loss of interest and initiative, irritability, and depressive moods. They also seem to affect people in different ways. The main symptom that classifies dementia is memory impairment, especially short term memory. Other functions that are often progressively lost during the disease 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 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 problem-solving
  • Difficulty handling complex tasks
  • Difficulty with planning and organizing
  • Difficulty with coordination and motor functions
  • Confusion and disorientation

Psychological changes

  • Personality changes
  • 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 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 stage is often missed due to the mildness and gradual nature of symptoms:

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

Middle stage – signs and symptoms become more pronounced and often noticeable:

  • Becoming forgetful of recent events and people’s names
  • Becoming lost at home
  • Having increasing difficulty with communication
  • Needing help with personal care
  • Experiencing behavior changes, including wandering and repeated questioning

Late stage – this stage is characterized by total dependence and inactivity. Memory disturbances are serious and the physical signs and symptoms become more obvious and interfere with daily life:

  • Becoming unaware of the time and place
  • Having difficulty recognizing relatives and friends
  • Having an increasing need for assisted self-care
  • Having difficulty walking
  • Experiencing behavior changes that may escalate and include aggression

Diagnosis (Part 7 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 of dementia. 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 other problems that can cause symptoms.

Some dementias, such as Alzheimer’s, are caused by known 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 8 of Is dementia genetic?)

Treatment depends on the cause of disease. In the case of most progressive dementias, including 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 Alzheimer’s symptoms. Early to moderate stage medication treats memory, thinking, language, and other thought process problems. Severe stage medication is more effective at improving these issues. Sometimes, the two medications 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

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 for dementia and Alzheimer’s 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.