Study Reveals Alzheimer’s Damages the Brain Prior to Symptom Onset

WASHINGTON — The insidious progression⁣ of‌ Alzheimer’s disease ​silently wreaks havoc on the brain long ​before any symptoms become evident. Recent scientific discoveries have shed light on the sequential changes that occur within the brain,⁤ potentially providing a window of opportunity for intervention.

In a comprehensive study ⁢conducted in ​China, researchers monitored middle-aged⁤ and older adults over ‍a span‌ of 20 years. The study employed regular‍ brain⁣ scans, spinal taps, and ‌other diagnostic tests to track the progression ‌of the disease.

The study⁢ revealed that individuals who eventually‌ succumbed to this debilitating disease had higher levels of a protein linked to Alzheimer’s in their spinal fluid, a full 18 years‍ before diagnosis. Subsequent years saw the emergence of other biomarkers indicative of impending trouble.

The‍ exact⁢ process ‌of how Alzheimer’s develops ‍remains a mystery to scientists. One early sign ⁢is⁢ the accumulation‌ of a sticky ​protein known⁢ as beta-amyloid, which over time forms plaques that ⁣clog the brain. However, the presence of amyloid alone is not sufficient to‍ impair memory, as‌ many healthy individuals’ brains contain‌ significant amounts of plaque.​ The formation of abnormal tau protein, which creates neuron-destroying tangles, is one of several contributing factors.

The⁢ groundbreaking research, ⁣published in the ⁤New England Journal of Medicine, provides​ a⁤ timeline of how these abnormalities accumulate. Dr. Richard Mayeux, an Alzheimer’s ​specialist at ‌Columbia University who was‍ not involved in the study, emphasized the significance of the research, ​stating‌ that​ understanding the timing ⁢of these physiological events is crucial for developing ‍new treatment methods and potentially even ‌preventing Alzheimer’s.

While the findings do not yet have any practical applications, they represent a significant step forward in our understanding of ⁣the disease.

Alzheimer’s⁣ disease, the most common form ‌of dementia, affects over 6​ million Americans and millions more worldwide. Currently, there is ‍no ‍cure. ⁤However, last year saw the approval of⁣ a drug named Leqembi, the first to show clear evidence of slowing the progression of⁢ early Alzheimer’s, albeit temporarily.

Leqembi ⁢works by​ clearing‍ some of the amyloid protein.⁢ This⁣ approach is also being tested to see if treating high-risk individuals before symptoms‍ appear⁣ can delay the onset of Alzheimer’s. Other drugs targeting tau are also in development.

Monitoring silent ⁣changes in the brain is crucial for such research. Scientists already knew that in rare, inherited forms⁣ of Alzheimer’s that affect younger people, a toxic form of amyloid begins to accumulate about two decades before symptoms appear, ⁢with tau kicking in⁤ at some point later.

The new ⁢findings reveal​ the sequence in which these biomarker changes occur in ⁢more​ common old-age Alzheimer’s. Researchers ​from Beijing’s Innovation Center for ‍Neurological Disorders compared 648 ⁢people who were eventually diagnosed​ with Alzheimer’s‌ with ⁣an equal number of healthy individuals.‍ They ‌found⁣ that the first sign in future Alzheimer’s patients was the amyloid finding,‌ 18 or 14 years before ​diagnosis, depending on the test⁣ used.

Next, differences in tau were detected, followed by a marker indicating‍ problems in neuron communication. ​A few years later, differences in brain shrinkage and cognitive test scores between the two groups became apparent.

“The more we understand about potential Alzheimer’s treatment targets and⁢ the optimal time to address them, the ‌faster ‌we can develop new therapies and preventative ‍measures,” said ⁢Claire Sexton, the Alzheimer’s Association’s senior director of scientific programs. She added that forthcoming blood tests promise to further aid research by making it easier to track amyloid and‌ tau.