Genetic variant that may protect against Alzheimer’s discovered

A genetic variant that may protect individuals against Alzheimer’s disease has been identified by researchers. The potential breakthrough was made by scientists at Washington University in St Louis in the ongoing quest to find ways to combat the condition.

Around 800 people participated in the study, which involved some with the neurodegenerative disease and other healthy individuals. Variations were found in the MS4A4A gene, leading to differing levels of the TREM2 protein, which is linked to Alzheimer’s.

While some of the variants meant lower levels of TREM2 and therefore an increased risk of developing the disorder, others led to higher levels and a reduced risk. This is because it’s thought that TREM2 ‘ingests’ amyloid beta and tau proteins in the brain, which cause Alzheimer’s.

Breakthroughs like this one can act as the foundation for developing new therapies and treatments, because there is currently no cure for the disease. Scientists across the planet are working on drugs based on varying principles. New approaches continue to offer hope that the epidemic can be reversed.

Figures from the Alzheimer’s Society suggest that 850,000 people in the UK have dementia. Alzheimer’s is the most common form of the condition and affects 62 per cent of those diagnosed. At present, the best chance of leading an independent life for as long as possible is to identify the disease early on, but this is difficult, as symptoms only appear once it has taken hold.

The situation is no better in the US, where 5.8 million individuals are living with the condition, the Alzheimer’s Association says. This is set to rise to 14 million by 2050, making it an issue that continues to top the health agenda. With longer life expectancies, conditions like Alzheimer’s become more common.

In previous studies it has become apparent that TREM2 plays a ‘critical role’ in the activation and survival of microglial cells. These immune cells are highly specialised and remove damaged neurons to ensure the central nervous system remains in good health. Scientists do not fully understand TREM2’s exact role in Alzheimer’s disease, but past research has suggested variations in it could mean the risk increases threefold.

The latest study involved analysing genes found in spinal fluid samples from 813 volunteers. The group was divided into 172 participants with Alzheimer’s, 221 displaying mild cognitive impairment, 68 with significant memory concerns and 169 who were cognitively normal.

It was revealed that variations in the MS4A4A and MS4A6A genes were linked to higher concentrations of TREM2 in the spinal fluid samples. These increased levels were in turn linked to a decreased risk of Alzheimer’s and a delayed onset in older age.

Dr Celeste Karch, co-senior investigator, said: “We observed TREM2 risk variants more often in people who had Alzheimer’s or were mildly cognitively impaired. It turns out that about 30 per cent of the population in the study had variations in the MS4A4A gene that appear to affect their risk for developing Alzheimer’s disease.

“Some variants protected people from Alzheimer’s or made them more resilient while others increased their risk."