MS may increase Alzheimer’s risk, new genetic analysis finds
T-cell changes linked to both disorders in analysis of genetic data
Multiple sclerosis (MS) may increase the risk of developing Alzheimer’s disease, according to a new analysis of genetic data.
The findings indicate genetic changes that influence the activity of immune T-cells may play a role in both MS and Alzheimer’s.
The study, “Multiple sclerosis as a genetic risk factor for Alzheimer’s disease: Insights from Mendelian randomisation,” was published in Neurodegenerative Disease Management.Â
Damage to the brain seen in MS, Alzheimer’s
MS is a disorder marked by inflammation that causes damage to healthy cells in the brain and spinal cord. Damage to the brain is also seen in Alzheimer’s, a form of dementia, and a growing body of evidence suggests abnormal brain inflammation plays a role in driving the disease.
Recent research has indicated people diagnosed with MS are more likely than the general public to develop Alzheimer’s, but the biological connections between these two disorders aren’t fully understood.
In this study, a team led by scientists in India investigated the relationship between MS and Alzheimer’s using a genetic analysis technique called Mendelian randomization.
In essence, the scientists identified genetic changes known to influence the risk of MS, then looked to see if those changes are more common among people with Alzheimer’s disease. If MS-related variants are more common in Alzheimer’s, it would support the idea that MS itself may predispose a person toward Alzheimer’s, according to the researchers.
Results revealed 44 genetic variations known to influence MS risk that also showed similar associations with Alzheimer’s. These associations suggest “that genetic predisposition to MS may increase the risk of developing [Alzheimer’s],” the researchers wrote.
After identifying the variants associated with both MS and Alzheimer’s, the researchers conducted a series of analyses to look at the functions of the implicated genes. The scientists found many of the genes are associated with the activity of immune cells called T-cells, particularly with subsets of T-cells called T-helper cells.
These immune cells act as marshals of the immune system, releasing signaling molecules to help coordinate the activity of various immune cells. The researchers speculated that genetic changes affecting T-helper cell activity might help set the stage for both MS and Alzheimer’s, lending further support to the idea that these two diseases are biologically linked.
“Taken together, these findings reinforce the notion of a causal effect of MS on [Alzheimer’s], particularly mediated by immune-regulatory mechanisms involving T-helper cell differentiation,” the scientists wrote.
A notable limitation of this analysis was that the genetic database the researchers used specifically included individuals of European descent. A similar analysis was conducted using a database of African Americans, but the researchers weren’t able to detect genetic variations with statistically significant results, likely because that database was much smaller. The scientists emphasized a need to validate these findings in more diverse populations.
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