When a decline in cognitive function impairs our social, occupational, or daily activities compared to our previous baseline, we are said to have dementia. However, these first cognitive abnormalities can first present as mild and have any number of causes, from Alzheimer’s disease, to vascular dementia (damage from strokes), Lewy body dementia, or frontotemporal dementia, to name a few.
A growing concern
Alzheimer’s disease, the most common cause of dementia, affects more than five million Americans, and those numbers are expected to triple in the next 30 years without treatment that prevents or delays its onset. Despite improved understanding of and treatments for Alzheimer’s disease in recent years, these have had a modest effect on the symptoms, and do not slow the relentless progression of the disease.
This is likely in part due to the fact that by the time someone has even mild dementia due to Alzheimer’s disease, there is already substantial brain damage, and the underlying brain lesions that cause dementia have been accumulating for some 20 years.
Clinicians and scientists have been hard at work on this problem. There are now ways to detect the brain lesions of Alzheimer’s disease during these early decades prior to the onset of cognitive decline. By using genetic testing as well as blood, spinal fluid, and neuroimaging tests in clinical trials during the presymptomatic stageof disease, we can identify the early brain changes underlying Alzheimer’s disease to try to develop preventative strategies.
Knowing earlier, knowing more
Since age and genetics are the major risks for Alzheimer’s, screening people, especially those with a family history of the disease, in middle age would make most sense to identify participants for preventative trials. Some such clinical trials have begun, but to date they represent a small minority of trials conducted in the field. This is likely because of the fact that disease-modifying clinical trials take years to conduct, and many want to first see if newly developed therapies would work in people with dementia. As our scientific understanding increases, we must ensure that our investment is focused on efforts to prevent dementia due to Alzheimer’s disease and other causes. This will give us the best chance for the biggest impact.
David M. Holtzman, MD, Professor and Chairman, Department of Neurology at Washington University School of Medicine, President of the American Neurological Association, [email protected]