Memory loss is one of the hallmarks of Alzheimer’s disease.
But it may be possible to reverse the symptom, restoring people’s memories, according to researchers.
Research published in the journal Brain suggests that a new approach using epigenetics – the study of chemical reactions and factors that influence genetics without changing the DNA sequence, effectively switching genes on and off, had shown it was possible to reverse memory decline.
Scientists used mouse models carrying the gene mutations for familial Alzheimer’s, where more than one member of a family had the disease, as well as post-mortem brain tissue from Alzheimer’s patients.
She said a key reason for cognitive decline in Alzheimer’s patients is the loss of glutamate receptors, which are critical to learning and short-term memory – itself the result of an epigenetic process known as repressive histone modification.
She said: “We found that in Alzheimer’s disease, many subunits of glutamate receptors in the frontal cortex are downregulated, disrupting the excitatory signals, which impairs working memory.”
By understanding that process, scientists could identify potential drugs that would reverse the process.
“Our study not only reveals the correlation between epigenetic changes and Alzheimer’s, we also found we can correct the cognitive dysfunction by targeting the epigenetic enzymes to restore glutamate receptors,” said Prof Yan.
“In this paper, we have not only identified the epigenetic factors that contribute to the memory loss, we also found ways to temporarily reverse them in an animal model of Alzheimer’s Disease.”
Researchers injected the Alzheimer’s animals three times with compounds designed to inhibit the enzyme that controls repressive histone modification.
Prof Yan said: “When we gave the Alzheimer’s animals this enzyme inhibitor, we saw the rescue of cognitive function confirmed through evaluations of recognition memory, spatial memory and working memory.
“We were quite surprised to see such dramatic cognitive improvement. At the same time, we saw the recovery of glutamate receptor expression and function in the frontal cortex.”
Future studies will be needed for long-lasting results, Prof Yan said, but she said an epigenetic approach works well for brain disorders such as Alzheimer’s because they allow the control of many genes rather than just one.
She added: “An epigenetic approach can correct a network of genes, which will collectively restore cells to their normal state and restore the complex brain function.”