Fact 5: The Role of Genetics in Alzheimer’s and Vascular Dementia – A Complex Interplay
Our understanding of the genetics of Alzheimer’s and Vascular Dementia has expanded significantly over the past few decades. It has become increasingly clear that genetic factors play a substantial role in determining an individual’s risk of developing these conditions. However, the relationship between our genes and these forms of dementia is far from simple. It’s a complex interplay between our genetic makeup, our environment, and the choices we make throughout our lives.
In the case of Alzheimer’s disease, several genes have been identified that can influence a person’s risk. Among the most well-known is ApoE-e4. Possession of this gene variant is considered the most substantial genetic risk factor for late-onset Alzheimer’s, which typically develops after the age of 65. However, not everyone who carries this gene variant will develop Alzheimer’s, and not everyone who has Alzheimer’s carries this variant. This seeming paradox highlights the multifactorial nature of the disease.
Several other genes are also associated with Alzheimer’s disease. For example, variants of the genes ABCA7 and SORL1 have been linked to an increased risk. Some gene variants are associated with an increased production of the protein amyloid-beta, which forms the plaques characteristic of Alzheimer’s. In contrast, other gene variants may affect the brain’s immune response or the processing of proteins within brain cells, contributing to Alzheimer’s development.
The genetic influence on Vascular Dementia is less straightforward. The cause of VaD is often tied to other medical conditions, such as stroke, where genetics play a less direct role. That being said, some genetic conditions can lead to VaD. For instance, the condition CADASIL (Cerebral Autosomal Dominant Arteriopathy with Sub-cortical Infarcts and Leukoencephalopathy) is a rare genetic disorder that leads to stroke and VaD.
However, it’s crucial to remember that despite the genetic risk factors associated with both Alzheimer’s and VaD, these diseases are not inevitable. Many people with these genetic risk factors will not develop dementia. Conversely, many people without these risk factors will. This emphasizes the significant role of non-genetic factors, such as environmental influences and lifestyle choices. (5)
