When the first symptoms of Alzheimer's, it is common for those who suffer from it do not remember some things of the day, but remember perfectly those that happened years ago. This is one of the first consequences of the development of this disease: your brain is unable to recall faces or places, but the problem is not that you have not processed that data, but that you do not remember where you stored them. The research that has led Zhen Yan breaks with this handicap and raises, now, the possibility of recover lost memories.
For this, they have used a epigenetic approach. That is, they have studied the modifications in the expression of genes that do not obey an alteration of the DNA sequence and that are inheritable. "Not only have we identified these factors that contribute to memory loss, but also the way reverse them temporarily", Has assured Zhen Yan, main author of the study that publishes the magazine" Brain "and professor of the Department of Physiology and Biophysics of the University of Buffalo.
Although there is no definitive statistics, the different associations of affected people calculate that, in Spain, there are 650,000 people over 65 they suffer Alzheimer's, which translates into 7% of the population. While this is not a disease associated with aging, it is true that virtually all affected exceed this age. Because each year there are more than 100,000 new cases and taking into account the aging of the population and the future increase of people over 80, it is expected that the number of patients will double in 2020 and triple in 2050.
The study was carried out in families of mice with genetic mutations, in which more than one member carried the disease, as well as in post-mortem brain tissues affected by Alzheimer's. It is not the first time it is done: in 2016, the Massachusetts Institute of Technology (MIT) proved that memories stored in the brain, although it is not easy to access them. Thus, they managed to recover them thanks to the stimulation of brain cells with light. This time, however, it has been thanks to epigenetics: it is known that this disease is the result of a series of genetic and environmental risk factors that combine to produce epigenetic changes. While this is clear, what is unknown is how this process occurs.
These changes occur mainly in later stages, when patients can not retain newly learned information and begin to develop a strong cognitive loss. One of the key reasons to understand this cognitive deterioration is in the loss of glutamate receptors, decisive in the processes of learning and short-term memory. "During the development of the disease, many of these receptors located in the frontal cortex begin to fail, interrupting the signals and affecting the working memory", added Yan. For the researchers, this loss is the consequence of a procedure in which histones are modified, proteins that condense and pack the DNA carefully into the chromosomes. "This abnormal alteration of histone is the one that suppresses gene expression and decreases glutamate receptors, which is what leads to memory deficits."
This idea has allowed them to develop drugs that inhibit the enzymes that produce this situation. "When we gave them to them, we observed that the cognitive function began to recoverand. This is confirmed after several evaluations of recognition, spatial memory and work ", explained Yan. "At the same time, there was recovery of glutamate receptor functions in the frontal cortex." However, the improvements only lasted a week. So future studies will now focus on developing compounds that penetrate the brain more effectively and, therefore, are more durable.