It turns out that some areas of the brain in patients with Alzheimer's disease are more damaged than others because of the APOE gene. It is most expressed in the temporal lobe of the brain, which is why they are first damaged in the disease, and memory disorders become the earliest symptoms. However, this study may also help explain the rare symptoms that occur in atypical in Alzheimer's disease .
Scientists from Washington University School of Medicine in St. Louis, USA have discovered why certain areas of the brain are particularly susceptible to Alzheimer's disease. It turns out that the APOE gene—one of the genetic risk factors for this disease—is most active in areas where the brain is most damaged. The results of this published by in the journal Science Translational Medicine also explain why the symptoms of Alzheimer's disease sometimes vary from patient to patient.
Memory loss is usually the first sign of Alzheimer's disease, followed by confusion and cognitive impairment . These symptoms reflect typical patterns of progressive brain tissue damage. The toxic accumulation of protein first focuses on the temporal lobe—the area responsible for memory—and then spreads to parts of the brain that are important for thinking and planning.
The culprit of Alzheimer's disease is β-amyloid , which forms amyloid plaques in brain tissue. Later, the accumulation of other abnormal proteins began to form - the neurofibrillary tangle of the tau protein . Shortly thereafter, tissue in the affected area will die.
There are also some rare, atypical Alzheimer's disease that can lead to speech and vision problems in the first place, rather than memory problems. Patients with atypical Alzheimer's disease are often excluded from the study because it is easier to study a group of people with the same symptoms. However, this heterogeneity suggests that scientists still do not fully understand how and why Alzheimer's disease develops.
The authors of this new work analyzed data from 350 people who volunteered to participate in memory and aging studies. They received a brain scan so that scientists could determine the number and location of amyloid plaques and tau tangles in the brain. The researchers compared the volunteers' patterns of protein accumulation and tissue damage with expression patterns of APOE genes and other genes associated with Alzheimer's disease.
It turns out that high expression of APOE gene is associated with increased accumulation of tau tangles and tissue damage. Other genes associated with Alzheimer's disease also showed similar patterns. All of these are expressed primarily in the temporal lobe. So there are something fundamentally different in these areas that make them susceptible to brain damage . According to scientists, this trait may depend on human genetics.
All people have the APOE gene, but those carrying one of these variants have a 12-fold higher risk of Alzheimer's disease than the average person. Now, researchers plan to study patients with atypical Alzheimer’s disease to see where in their brains APOE expression increases and which variants of the gene they carry.
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