A leading concern amongst family members of dementia patients is whether they are at a risk of developing the disease themselves, due to hereditary genetic patterns and mutations. The answer, in most cases, is a definitive no, as dementia can be attributed to an array of reasons, only one of which is genetic transfer.
However, since Alzheimer’s disease along with other forms of dementia can also be associated with genetics; individuals having multiple family members who have any form of dementia have a higher propensity of developing the disease in their later years. Such individuals should consult neurologists and undergo regular testing to ensure the immediate diagnosis of any memory loss disorder.
The research in the domain of dementia is still young, therefore, no isolated cause-and-effect association can be made between the various forms of dementia and genetic transfer. To consider an example, frontotemporal dementia or FTD is thought to have genetic implications. Despite this fact, over 50% of identified cases of frontotemporal dementia exhibit no family history of the disease.
Genetics of Dementia:
Dementia manifests itself in a number of forms including Alzheimer’s disease, vascular dementia, dementia with Lewy bodies, frontotemporal dementia, dementia from Parkinson’s disease and Creutzfeldt-Jakob disease. Following is a detailed insight into the genetics of the various forms of dementia:
The most common form of dementia is Alzheimer’s disease which constitutes nearly 80% of all recorded cases of dementia. The involvement of genetics has been confirmed in the case of early AD, however, researchers are still underway to the underlying cause of late-onset AD:
Early-onset Alzheimer’s disease:
Recent studies have identified several single-gene mutations that cause early-onset Alzheimer’s disease (development of Alzheimer’s prior to 60 years of age). In such instances, the disease is caused by mutations in presenilin 1 (PSEN1), presenilin 2 (PSEN2) and amyloid beta A4 protein precursor (APP) genes which instigate brain damage owing to the production of abnormal proteins. However, such cases only comprise of 5% of all reported cases of Alzheimer’s disease.
Late-onset Alzheimer’s disease:
Researchers are unsure of genetic causes leading to late-onset Alzheimer’s disease, as they are still trying to associate it with particular genetic mutations. So far, they have identified a single gene variant of apolipoprotein E (ApoE) which is caused by vascular problems affecting the brain’s supporting structures and memory regions and increases a person’s propensity to develop Alzheimer’s disease as well as vascular dementia.
ApoE prompts the body to produce a protein that assists in the removal of cholesterol by transporting it through the bloodstream. A variation of the ApoE known as ApoE4 is found in nearly 25% of the population. It does not cause Alzheimer’s disease or vascular dementia, however, it houses the capability to cause changes in brain cells that may lead to a decline in cognitive abilities.
Though it is still unclear how the ApoE4 affects brain cells, it has been observed that people who possess the gene variant age at a rapid pace. The reason for this is that ApoE4 causes a decline in the functioning of nerve cells in the frontal lobe which is significant in enabling mental functioning. This rapid loss of nerve cell performance can elevate the risk of dementia. ApoE is capable of degrading clusters of the beta-amyloid protein (which fills in the spaces that exist between brain cells). The presence of ApoE4, however, stops the breakdown of beta-amyloid clusters. For this reason, ApoE4 is associated with an unusual presence of beta-amyloid clusters in the brain.
It has been observed that individuals possessing two copies of ApoE4 are at a higher risk of Alzheimer’s disease as opposed to individuals possessing only a single copy. It is important to mention here that the presence of this variant cannot definitely predict the development of Alzheimer’s disease because all individuals with Apoe4 are not guaranteed to develop Alzheimer’s disease and likewise all Alzheimer’s disease patients are not guaranteed to have the ApoE4.
There are other gene variants that have been found to increase the risk of development of Alzheimer’s disease. These variants are associated with the cell division cycle 2 gene (CDC2), which increases the production of the proteins ubiquilin-1 and tau which control deposit, accumulation, and breakdown of multiple proteins associated with the various forms of dementia.
Huntington’s disease, a far less common form of dementia, has distinct hereditary patterns. In the case of Huntington’s, the offspring of a parent inflicted with the ailment has a 50-50 probability of developing it.
Frontotemporal dementia (FTD):
Frontotemporal dementias cause a decline in social behaviors, speech and various brain functions other than memory, and are associated with 5 gene mutations. Genetics are known to cause only half of the cases of FTD.
Dementia with Lewy Body:
Dementia with Lewy Body is rarely caused by genetic transfer. It has been observed, only 10% of the time, to be caused by genetic mutation or transfer.
However, new research reveals that 7.6% people with pure Lewy body disease (no co-existing Alzheimer’s pathology) carried a GBA mutation – a gene associated with a completely different disorder; the Gaucher’s disease — which may play a role.
Dementia can also be caused by Parkinson’s disease which is not genetically transmitted, however, its presence increases the risk of development of dementia.
Diagnosis and Prevention:
Though dementia is irreversible, physicians are capable of effectively detecting the presence of the above-mentioned gene variants via diagnostic procedures. Diagnosis of dementia can be a complicated endeavor because the presence of gene variants need not necessarily guarantee its development. This lack of uncertainty may lead to unnecessary stress, should the ailment not develop, and recklessness, should there be a viable threat.
Currently, there is no known cure for dementia. However, there are chances of reducing the pace of its development and improve the quality of life of patients via an early diagnosis and intervention. Early intervention in the case of dementia, poses a dilemma that is signature to cognitive ailments and involves hesitation of suspecting individuals to open up about their concerns.
Self-care apps including BrainTest allow suspecting individuals as well as their family and caregivers to conduct a self-administered cognitive screening test to detect early signs of cognitive impairment. These signs can be caused by various ailments including dementia and can act as the basis for a detailed clinical diagnosis.
Consultation and Guidance:
Individuals who have family members with dementia or are experiencing cognitive difficulties should immediately seek medical consultation. They will be appraised of the risk that they may face, along with measures that they can undertake to improve their quality of life.
Kamil Riaz is a Writer and Digital Marketer. He has completed his masters in Administrative Science from the University of Karachi. As a writer, he wrote numerous articles on health, marketing, management, and technology.