Genetics and Alzheimer's Disease
Alzheimer's disease is one of the most common neurodegenerative disorders in the world. From the sixth decade of life, the risk begins to multiply (1). It is a progressive disease, currently without a cure, which manifests itself mainly in memory problems and is usually accompanied or evolves into disorientation in space, attention problems, personality and mood changes, inability to communicate, and even impairment of motor functions, among other factors symptoms. This pathology affects all ethnic groups of humanity, and one of the factors with the most significant impact is the increase in our life expectancy. The longer we live, the more our brains are subject to the possibility of neurodegeneration (2).
Early or late-onset Alzheimer's disease.
Even today, much of the operating mechanisms of the pathology remain largely unknown, but fortunately, in the field of genetics, we have an increasingly better understanding of which genes influence dementia. For example, one of the most directly related to early Alzheimer's is the PSE1 gene. Recognized genes such as APOE are a risk factor in late-onset Alzheimer's disease (4).
Up to 90% of Alzheimer's is genetic.
Alzheimer's is a complex disease, and this makes the search for causes difficult. In complex diseases, genetics is an essential factor to consider, but environmental factors such as stress, diet, or where we live also play a role. Recent genetic studies indicate that there is still much to be discovered in our DNA (4); when we talk about hereditary factors, some research points to up to 80% of genetic causes in the development of the disease. And this percentage increases to more than 90% in the case of early-onset Alzheimer's disease.
Aducanumab, a light at the end of the tunnel
The development of most drugs focuses on particular pathology parts, such as the amyloid cascade (8). Unfortunately, not many have been approved and developed. However, we have recently witnessed the approval of Aducanumab (9), which is a milestone and shows us some light at the end of the tunnel.
24Genetics includes Alzheimer's in its Health Report
As a curiosity, in recent decades, a decrease in the incidence of Alzheimer's disease has been observed in certain parts of the world (10). Still, much remains to be discerned, given that the pathophysiology of this disorder has not yet been fully understood (11, 12). However, within the little we currently know at the genetic level, 24Genetics develops in several sections of its health report, an analysis of genetic predisposition to Alzheimer's disease.
For this section of our report, we apply GWAS. This statistical analysis methodology compares the DNA markers of people with a disease or trait with people without this disease to identify genetic differences. These studies can be beneficial for prevention and early diagnosis. However, even if they are not diagnostic tools, they tell us whether we should pay more attention to certain areas of our health.
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Bibliography:
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- Wolters,J., et al. (2020). Twenty-seven-year time trends in dementia incidence in Europe and the United States. The Alzheimer Cohorts Consortium. Neurology. 95 (5) e519-e531; DOI: 10.1212/WNL.0000000000010022
- Bertram, L., et al. (2010). The Genetics of Alzheimer Disease: Back to the Future. Neuron, 68, 270-281.
- Sims, R., et al. (2020). The multiplex model of the genetics of Alzheimer's disease. Nature Neuroscience, 23, 311-322.
- Lambert, J., et al. (2013). Meta-analysis of 74,046 individuals identifies 11 new susceptibility loci for Alzheimer's disease. Nature Genetics, 45, 1452-1458.
- Sims, R., et al. (2020). The multiplex model of the genetics of Alzheimer's disease. Nature Neuroscience, 23, 311-322.
- Efthymiou, A.G., & Goate, A. (2017). Late onset Alzheimer's disease genetics implicates microglial pathways in disease risk. Molecular Neurodegeneration, 12.
- Mullard, A. (2021). Landmark Alzheimer's drug approval confounds research community. Nature 594, 309-310. doi: https://doi.org/10.1038/d41586-021-01546-2 .
- (10) Knopman, D.S. The Enigma of Decreasing Dementia Incidence. JAMA Netw Open. 2020;3(7):e2011199. doi:10.1001/jamanetworkopen.2020.11199
- (11) Bihlmeyer, N., et al. (2019). Novel methods for integration and visualization of genomics and genetics data in Alzheimer's disease. Alzheimer's & Dementia, 15, 788-798.
- (12) Bellenguez, C., et al. (2020). Genetics of Alzheimer's disease: where we are, and where we are going. Current Opinion in Neurobiology, 61, 40-48.
