Study gives clues to why Alzheimer's disease damages certain parts of the brain

Memory loss is the first sign of Alzheimer's disease, followed by confusion and difficulty thinking. These symptoms reflect the typical pattern of worsening damage to brain tissues. Toxic clusters of proteins are concentrated in the temporal lobes the memory area of the brain before spreading to parts of the brain that is important for thinking and planning.

The findings, published in Science Translational Medicine, help explain why symptoms of Alzheimer's disease sometimes vary, and highlights an understudied aspect of Alzheimer's disease that suggests yet-to-be discovered biological mechanisms may play an important role in the disease.

A study by researchers reports clues to why certain parts of the brain are particularly vulnerable to Alzheimer's damage. It comes down to the gene APOE, the greatest genetic risk factor for Alzheimer's disease. The parts of the brain where APOE is most active are the areas that sustain the most damage.

Researchers studied 350 people who volunteer for memory and aging studies through the School of Medicine's Charles F. and Joanne Knight Alzheimer Disease Research Center. The participants underwent brain scans so the researchers could measure the amount and location of amyloid plaques and tau tangles, and the volumes of various brain areas.

The researchers compared the patterns of protein clumps and tissue damage in the volunteers to the gene expression patterns of APOE and other genes associated with Alzheimer's disease as depicted in the Allen Human Brain Atlas, which is a detailed map of gene expression in the human brain compiled by the Allen Institute for Brain Sciences.

Researchers concluded that APOE4 carriers are more likely to start accumulating amyloid, which puts them on the path to Alzheimer's. Then, for the same amount of amyloid they get more tau tangles, which leads to more atrophy. It's a double hit on the brain. They added that further research is needed in this field.

Reference:

Study yields clues to why Alzheimer's disease damages certain parts of the brain; Science Translational Medicine, DOI: 10.1126/scitranslmed.abl7646.