Alois Alzheimer (1864–1915)
As our population ages, so will the increased prevalence of Alzheimer’s disease (AD), arguably the most terrifying consequence of aging, with the loss of memory and of the self. The World Health Organization estimates that four of every 1,000 people worldwide will have AD in 2015. Scientists are searching for causes, for ways to detect it earlier, and for drugs that will prevent, slow, and even reverse its progression.
In 1906, German psychiatrist-neuropathologist Alois Alzheimer accurately described a patient with progressive memory, language, and behavioral problems. Upon her death, he found changes in brain tissue—namely, the presence of twisted bands of fibers (neurofibrillary tangles) and dense deposits surrounding nerve cells (neuritic plaques). Six decades later, scientists recognized that a correlation existed between the mental decline and these specific brain changes, leading to the recognition that AD is a disease and not an inevitable consequence of aging.
These damaging brain changes begin long before—perhaps one or more decades before—memory loss or cognitive decline appears. Some scientists believe that when these cognitive signs become evident, the damage has been done, and it’s too late for existing drugs to correct the underlying causes. Researchers are exploring simple and accurate diagnostic tests for AD before cognitive symptoms appear. PET scans of the brain, involving radioactive imaging, are able to detect plaques, and spinal taps can detect beta-amyloid, a protein that forms plaques. Still farther back in the disease process are genetic influences (such as the ApoE4 gene) that increase the risk of AD by hastening the accumulation of beta-amyloid.
If these diagnostic tests for early detection of AD prove reliable, ongoing debates will swirl in the medical community: How early should individuals with memory deficits be labeled with AD? More fundamentally, should such diagnostic tests even be conducted in routine medical practice, since AD is currently untreatable?
One active approach in anti-AD–drug development is looking at how to block gamma secretase, an enzyme that chops down a larger protein to form beta-amyloid. Clearly, other approaches are needed to combat this devastating disorder.
SEE ALSO Neurotransmitters (1920), Cognex and Aricept (1993), Smart Drugs (2018).
Two elderly men are playing Xiangqi or Chinese chess, one of the most popular board games in China. Some research suggests memory games may slow the progression of Alzheimer’s disease.