Research indicates that blood and cerebrospinal fluid tests provide relevant prognostic information for elderly patients, challenging the idea that aging makes these tests less useful.
Researchers at the Sant Pau Research Institute found that Alzheimer’s disease biomarkers can predict rapid cognitive decline in individuals aged 80 and older. The study, published in Neurology, suggests that identifying underlying pathology provides relevant clinical information even in very old patients with multiple coexisting conditions.
The findings challenge the belief that biomarkers have limited value at advanced ages. Identifying the biological markers associated with the disease helps clinicians anticipate patient progression more accurately.
“Not every memory problem after age 80 is normal, and assuming that it is can lead to the underdiagnosis of diseases such as Alzheimer’s,” says Ignacio Illán-Gala, researcher with the Neurobiology of Dementias Group at Sant Pau Research Institute and neurologist at Sant Pau Hospital, in a release. “We need to overcome the influence of ageism in the care of these patients and move toward a more accurate diagnosis, including at advanced ages.”
Diagnostic Accuracy in Older Adults
Diagnoses based exclusively on clinical assessment are often limited in accuracy for patients over 80. In routine practice, many of these patients are evaluated without biomarkers, leading to uncertainty regarding the cause of symptoms. This uncertainty is often due to the high frequency of coexisting neurodegenerative diseases, vascular abnormalities, and other aging-related processes.
In addition, as age increases, differences in cognitive performance between people with and without Alzheimer’s disease tend to become smaller during early stages.
“Older patients often have many coexisting conditions that can impact memory, and relying solely on clinical assessment may lead to inaccurate diagnoses,” says Chiara Ceriello, geriatrician at Sant Pau Hospital and first author of the article, in a release. “In fact, approximately half of the cases do not correspond to pure Alzheimer’s disease, which means that, without biomarkers, it is difficult to determine what is causing the cognitive decline and to accurately anticipate its progression.”
Biomarkers and Patient Outcomes
The study analyzed 167 people over age 80 with mild cognitive impairment from the Sant Pau Initiative on Neurodegeneration cohort. Nearly 70% of participants had biology consistent with Alzheimer’s disease, determined by analyzing proteins in cerebrospinal fluid—such as the ratio of p-Tau181 to beta-amyloid—and the blood-based correlate, p-Tau217.
Patients with Alzheimer’s disease biology experienced more rapid cognitive decline than those without evidence of the disease, according to the Mini-Mental State Examination. Those with the biology showed an average decline of 0.47 points per year, compared with 0.18 points per year for those without.
Higher levels of p-Tau217 were also associated with a greater risk of progressing to dementia, with risk increases approaching 50% depending on biomarker levels.
“As age increases, differences in memory performance between people with and without Alzheimer’s disease tend to become smaller, making the disease more difficult to identify based solely on clinical assessment,” says Illán-Gala, in a release. “However, what does differ clearly is the course of the disease: people with this biology have a worse prognosis and more rapid progression of cognitive decline over the medium term.”
Clinical Implementation via Blood Tests
The study highlights the potential for blood-based biomarkers to facilitate diagnosis in geriatric care. Unlike traditional methods like lumbar puncture or positron emission tomography (PET), blood tests offer a simpler and more accessible approach.
“The availability of a blood-based biomarker makes it much easier to incorporate this assessment into clinical practice, particularly for older patients,” says Ceriello, in a release. “It allows us to obtain relevant biological information in a simpler and more practical way, and this has a direct impact on how we assess and monitor these patients.”
The researchers note that these biomarkers should be interpreted within the clinical context of the patient, including factors such as frailty, comorbidities, and baseline functional status.
“Precision medicine should not have an age limit,” says Ceriello, in a release. “In well-preserved patients with a good quality of life, knowing whether biomarkers are present can change clinical management, prognosis, and future planning.”
Photo caption: Dr Chiara Cierello and Dr Ignacio Illán
Photo credit: IR Sant Pau
