For years, the pursuit of a cure for Alzheimer′s disease has been a competitive and contentious quest. For instance, in June 2021, the U.S. Food and Drug Administration approved aducanumab, an antibody-targeting beta-amyloid, as a treatment for Alzheimer′s even though the data supporting its use was incomplete and contradictory. Some experts believed that aducanumab should never have been approved, while others wanted to give it a chance. All the scientists have been focused on trying to come up with new treatments for Alzheimer′s by preventing the formation of brain-damaging clumps of this mysterious protein called beta-amyloid.

However, a study conducted at the Krembil Brain Institute, part of the University Health Network in Toronto, has helped in devising a new theory on Alzheimer′s disease. According to the theory, Alzheimer’s is not a disease of the brain but principally a disorder of the immune system within the brain. The research scientist claimed that beta-amyloid is not an abnormally produced protein, rather it is produced normally as a part of the brain′s immune system. Therefore, when regarded as a misdirected attack by the brain′s immune system on the very organ it is supposed to be defending, Alzheimer′s disease emerges as an autoimmune disease.

When brain trauma occurs or when bacteria are present in the brain, beta-amyloid cannot tell the difference between invading bacteria and host brain cells due to the similarities between the fat molecules that make up both the membranes of bacteria and the membranes of brain cells. Beta-amyloid cannot tell the difference between invading bacteria and host brain cells. Hence, it attacks the very brain cells it is supposed to be protecting by mistake, leading to chronic, progressive loss of brain cell function, which ultimately culminates in dementia. 

(Source: https://www.theweek.in/news/health/2022/09/20/alzheimer-s-might-not-be-primarily-a-brain-disease0.html )