Memory problems after age 80 are still routinely written off as ordinary aging. A study led by researchers at the Sant Pau Research Institute (IR Sant Pau), published in Neurology, argues that this assumption is costing patients an accurate diagnosis. Among people aged 80 and older with mild cognitive impairment, the researchers found that Alzheimer's disease biology, identified through biomarkers in cerebrospinal fluid and in blood, was not only common but consistently linked to faster cognitive decline and a higher risk of progressing to dementia.
That result addresses a specific objection clinicians have raised about biomarker testing in the oldest patients: at very advanced ages, so many overlapping conditions can affect memory that a positive Alzheimer's marker was assumed to tell you little about what happens next. The Sant Pau data point the other way. Even in this clinically messier population, knowing whether Alzheimer's pathology is present still carried real prognostic information about how a patient was likely to fare.
The practical stakes are about who gets investigated at all. As Dr. Ignacio Illan-Gala, a researcher with the Neurobiology of Dementias Group at IR Sant Pau and a neurologist at Sant Pau Hospital, put it, not every memory problem after 80 is normal, and treating it as normal leads to underdiagnosis of diseases such as Alzheimer's. He framed the problem partly as ageism in clinical care, and called for more accurate diagnosis at advanced ages.
Blood-based markers matter here as well. The study drew on both cerebrospinal fluid and blood measures, and blood testing is far less invasive than a lumbar puncture - a meaningful consideration for frail patients in their eighties and nineties. The broader shift the authors are pushing for is one of expectations: that decline in the very old deserves a cause, not a shrug.