A gene variation could be the cure for Alzheimer’s disease according to results from a recent study.
Alzheimer’s disease is the most common cause of dementia in older adults. Brain changes include abnormal clumps (amyloid-β plaques), tangled bundles of fibers (tau tangles), and the eventual death of nerve cells. These changes lead to a progressive decline in memory, thinking skills, impaired motor function and death.
In the search for a cure, several researchers are investigating the known genetic causes of Alzheimer’s. For example, Some rare forms of this disease can be caused by variations in a single gene. These variants cause symptoms of cognitive decline by the time carriers reach middle age. Indeed, this atypical as the usual age of onset of Alzheimer’s starts in the late 60’s.
Gene Variation: Study Results
Researchers from the Harvard Medical School studied an extended family in Columbia, South America who are affected by one such gene variant, a gene called PSEN1. Of more than 6,000 people in this family, about 1,200 carry the Alzheimer’s-causing PSEN1 mutation.
With the exception of a single woman, all of the family members with the PSEN1 mutation developed symptoms of mild cognitive impairment and Alzheimer’s dementia in their 40s.
This woman didn’t develop any symptoms of cognitive decline until her 70s.
The researchers then carried out comprehensive testing, such as brain imaging and whole-genome sequencing, to find the protective factors.
Brain imaging showed that the woman had high levels of amyloid-β plaques in her brain. But, she had low levels of tau tangles. She also had less damage to her brain than would normally be seen in people with Alzheimer’s.
Whole-genome sequencing revealed that she carried two copies of a rare variation in the gene APOE. This rare gene variation is called APOE3ch.
Different variations of APOE have previously been linked to either protection from or increased risk of Alzheimer’s disease.
The research team found that this APOE3ch variation prevented the APOE protein to bind to a type of sugar called HSPGs. This binding helps tau tangles develop and spread throughout the brain.
Researchers then manufactured antibodies that targeted the region where the APOE3ch mutation is. These antibodies reduced the binding of normal APOE to HSPGs to the same levels as seen with APOE3ch.
The findings suggest that therapies to reduce the binding of APOE to the HSPG sugar cells may be a way to treat or prevent Alzheimer’s disease.
More research is underway. Stay tuned.