The first detectable marker of Alzheimer's is memory loss.
Popular coverage of Alzheimer’s tends to fixate on memory loss as the first tell. A 2017 article from Women’s Health, for example, cites “regularly being forgetful with routine tasks like cooking dinner,” along with other memory-related symptoms such as missing appointments and repeating conversations, as key indicators. Reader’s Digest similarly points to “worrying about your memory” and “spotty recollection of recent important events” as “early signs of Alzheimer’s.”
There is growing evidence, however, that Alzheimer’s disease begins its attack on the brain many years before such symptoms appear, leading researchers to suggest that there is a syndrome called preclinical Alzheimer’s disease. By repeatedly imaging the same individuals over time, scientists have learned that the amyloid protein is one of the earliest markers of the disorder. In fact, 20 to 30 percent of healthy adults over age 65 with no memory symptoms show evidence of amyloid deposits, indicating that the disease can be identified well before its most notorious symptoms set in.
Reisa Sperling, a leading Alzheimer’s researcher at Harvard Medical School, has proposed that there may be markers of Alzheimer’s present in the brain as early as middle age. The Harvard Aging Brain Study
, started in 2010 and led by Sperling, and the Dallas Lifespan Brain Study
, led by me and initiated in 2008, are capturing the slow transition from a healthy brain to Alzheimer’s by studying the same normal middle-aged and older adults for years. We hope to isolate an early neural and behavioral footprint of Alzheimer’s disease in middle-aged adults, as well as determine the characteristics of adults whose brains remain healthy and cognitively resilient.
Early diagnosis makes Alzheimer's easier to treat.
Research is leading to earlier and earlier identification of the disease, but can that help patients? “Early Detection Could Be Key to Effective Alzheimer’s Treatment,” said a 2017 headline on Healthline. Today’s Caregiver magazine, likewise, claims, “An early diagnosis is crucial because that is when the most can be done to slow the progression of symptoms.”
At present, however, there are no effective treatments to prevent or slow Alzheimer’s disease and hence, no clinical advantage to an early diagnosis. Clinical trials have found that by the time Alzheimer’s is diagnosed, it is too late to intervene with anti-amyloid agents. A recent large clinical trial that focused on adults in an early phase of the disease showed no benefit from anti-amyloid drugs. This has led to a debate as to whether amyloid is even a cause of Alzheimer’s. Perhaps it is merely a marker of the disease — just like gray hair is a marker of old age, not a cause.
Alzheimer's is an undiscriminating tormentor.
“Alzheimer’s affects everybody. It’s an equal opportunity killer,” author Niki Kapsambelis told Salon last year. Some take that premise even further: According to Alzheimer Europe,
“There is no conclusive evidence to suggest that any particular group of people is more or less likely to develop Alzheimer’s disease. Race, profession, geographical and socio-economic situation are not determinants of the disease.”
It turns out, however, that a life of privilege (financial security, higher social class and high levels of education) appears to confer some limited protection from Alzheimer’s. For example, Yaakov Stern of Columbia University studied 593 older adults who lived in Manhattan and found that over time, those who were less educated and held lower-status jobs were diagnosed with the disease at younger ages compared with those who were more privileged. The initial advantage faded, however, as highly educated individuals declined at a faster rate once they were diagnosed with Alzheimer’s disease. Other studies have reported similar findings.
Stern has proposed that high levels of education and a lifetime of intellectual work associated with higher-status jobs create a type of “reserve” that can be drawn upon to protect performance as an individual becomes cognitively frail or develops early Alzheimer’s.
You can prevent Alzheimer's disease by brain training.
The idea that exercises and discipline can ward off the worst is understandably seductive. “Brain training can reduce dementia risk,” declared a 2017 Cognitive Vitality headline. SeniorLiving.org also proposes that such games can “prevent dementia” and “help avert the onset of cognitive impairments among older adults.”
But there is no credible scientific evidence indicating that commercially available brain training programs will slow the mind’s march toward Alzheimer’s. Practice on a specific game might help an older person achieve the performance of a younger person on that game, but this will not reverse brain aging. There is, nevertheless, a fierce debate among cognitive neuroscientists as to whether various forms of brain training result in limited benefits to general memory function or improved performance in everyday life. On balance, an exhaustive review of the evidence by a group of scientists led by Dan Simon at the University of Illinois concluded that for the overall public, the benefits of mass-marketed brain training are nonexistent or small.
Smelling peanut butter can help diagnose Alzheimer's.
“Creamy or crunchy — and oh, so spreadable — peanut butter is . . . a possible game-changer in Alzheimer’s disease research,” began a 2015 post on the Cleveland Clinic website. That claim, based on a small study conducted at the University of Florida, was circulated widely by many highly credible sources after the initial research was published in 2013. Promoting the premise, a writer for “alternative health” entrepreneur David Wolfe’s website claimed that the study’s results would “help predict and address the disease before it becomes completely overwhelming for those diagnosed.” Further research did not support this finding. Although the research team responsibly acknowledged this, it can be very difficult to correct misconceptions once they are established, as my own work on false medical claims has shown.
definitive diagnosis of Alzheimer’s disease requires that there be an overabundance in the brain of two proteins: beta amyloid plaques and tau neurofibrillary tangles. This diagnosis occurs when a pathologist examines slices of brain tissue obtained after an autopsy and sees the sticky amyloid deposits and remnant tau tangles associated with Alzheimer’s.
Recently, however, researchers have developed tools to identify these amyloid deposits in living people via PET scans. Spinal fluid also provides a measure of amyloid burden. These “biomarkers” of Alzheimer’s disease are the frontier of much new research. If a PET scan is negative for amyloid, Alzheimer’s can definitively be ruled out. If it is positive, and neuropsychological tests show abnormal memory and cognitive function, an Alzheimer’s diagnosis is almost certain.