How can the risk of Alzheimer’s be measured even before symptoms appear?

Wouldn’t it be great if long before the diagnosis of a chronic illness, we could know it was coming, and had the time to do something about it? This might sound like something from a sci-fi movie, but in reality, scientists have made this possible for Alzheimer’s disease. But is it so simple to determine the risk of a disease that takes years and even decades to show symptoms? Alzheimer disease is the most common form of dementia, consisting 60 to 70% of the 57 million worldwide dementia patients, as per World Health Organization (WHO) fact sheets. AD is a progressive neurodegenerative disorder, which means it gradually damages the brain over time and resultantly affects memory, thinking and behaviour. Late-onset Alzheimer’s is the most common case and occurs after the age of 60, but rare cases can happen even earlier. The preclinical Alzheimer stage is when changes are taking place in the brain, but the symptoms or damage isn’t visible yet. This is also referred to as the ‘silent’ phase. In simple terms, long before memory loss hits, the blood in the body is witnessing protein changes. It is important to note that not all Alzheimer’s risk tests are easy to access. Some tests are expensive or invasive. Research concludes that blood biomarker tests for Alzheimer's are 80 to 90% accurate.Amyloid-beta accumulationis one of the earliest signs of Alzheimer’s and can start 15 to 20 years before memory loss begins. Blood tests and spinal fluid tests can measure the ratio of two amyloid forms.Phosphorylated tauoften follows amyloid changes and becomes another hallmark of AD. Measuring p-tau217 or p-tau181 in blood or spinal fluid can reveal when this process begins. Cognitive screening tests measure subtle changes in memory, attention or problem-solving before full dementia develops. Tests like the Montreal Cognitive Assessment (MoCA) or Mini-Mental State Exam (MMSE) are widely used tests and can be done within 10 to 15 minutes. Genetic testing tells about the lifetime risk of Alzheimer’s and not if an individual is currently having it. With genetic counseling, this test can be done through DNA kits or through a medical professional. Genetic testing measures APOE gene status or Polygenic risk scores. Identifying the risks early is like buying time for the brain and helps in accessing new treatments. Lecanemab and donanemab are some medications that have shown benefits in the preclinical Alzheimer stage. In other words, early detection allows individuals to act while the brain is still healthy and opens opportunities for intervention and hope.Also See: Alzheimer’s disease: Causes, early symptoms, and 11 lifestyle changes that could help prevent it