Alzheimer's care is moving beyond waiting for memory loss to become disabling. Blood tests for p-tau217 and two new drugs are changing how doctors diagnose and treat the disease. The shift is already reaching clinical practice, even though Spain's Commission for Interministerial Prices on Medicines has issued a negative resolution on funding either therapy.
The change starts with a blood sample. For decades, confirming Alzheimer's often meant a lumbar puncture or a tau-specific PET scan. Both are expensive, invasive and difficult to access.
Research led by Lund University in Sweden with the Pasqual Maragall Foundation found that plasma p-tau217 identified amyloid pathology with 81% accuracy. A two-stage protocol starts with the blood test. Only positive cases then go on for imaging or cerebrospinal-fluid analysis. The approach cut invasive testing by more than 40% without reducing diagnostic reliability.
The laboratory result is becoming more than a simple yes-or-no answer.
Data presented at the 2026 International Conference of the Alzheimer's Association showed that blood p-tau217 was not inferior to amyloid PET when identifying Alzheimer's disease in people without symptoms. A JAMA study also linked higher concentrations to later decline. Patients with very high levels had an absolute 38% risk of developing cognitive impairment within five years, compared with 24% among those with merely high levels.
That is why the Alzheimer's Association has issued its first clinical practice guideline on blood biomarkers in Alzheimer's & Dementia. A relatively inexpensive test could be introduced in primary care. PET scans and lumbar punctures could then be reserved for cases that need confirmation. The FDA has also stressed that doctors must interpret a blood result alongside a patient's medical history and cognitive testing, as well as a neurological assessment. Imaging or cerebrospinal-fluid analysis may still be needed.
Early detection matters because treatment has finally moved beyond managing symptoms alone. Lecanemab and donanemab are monoclonal antibodies aimed at beta-amyloid. They arrived after more than 200 medicines failed in phase III trials during two decades of therapeutic disappointment.
In the Clarity AD trial published in the New England Journal of Medicine, lecanemab reduced cognitive decline by about 27% after 18 months. The TRAILBLAZER-ALZ 2 trial published in JAMA reported a reduction of up to 35% with donanemab among patients with the lowest tau burden.
Neither medicine restores lost memory or cures the disease. Both slow progression only in people diagnosed at a very early stage. Both also require close monitoring because of ARIA, which can involve brain swelling or microhaemorrhages. The European Medicines Agency has authorised both drugs. Spain's pricing decision has drawn protests from the Sociedad Española de Neurología. As of September 2026, Spanish public financing for lecanemab and donanemab remains unresolved. Both are listed as not financed by resolution. Reports have put the potential annual cost at roughly €24,000-€32,000 per patient, alongside safety concerns.
The value of acting early becomes clearer when families spend years searching for answers, as shown in an earlier report. Alzheimer's research is now trying to shorten that period of uncertainty by combining screening with treatment before irreversible damage becomes dominant.
A third line of research looks at inflammation and metabolism. The phrase "type 3 diabetes" is not an official medical category. It describes the idea that the brain can become resistant to insulin, contributing to chronic low-grade inflammation and neuronal damage. Familiar preventive steps include a Mediterranean diet and regular physical activity, along with weight and glucose control. Good-quality sleep and sustained cognitive and social activity are also part of the approach. Evidence suggests that acting on these factors could delay up to 40% of dementia cases.
Newer studies are examining whether p-tau217 can help predict when cognitive decline may begin, instead of simply detecting existing Alzheimer's-related pathology. A 2026 pooled analysis found that higher concentrations were associated with greater risk, particularly among people carrying the APOE ε4 variant. These results are intended for risk assessment and research selection, not precise predictions for individual patients.
Bill Gates wrote about his father's diagnosis on Gates Notes and described the helplessness of waiting for a cure. His father died in 2020. Six years later, Gates has taken a more optimistic view of Alzheimer's research. That optimism draws on blood biomarkers and disease-modifying medicines, alongside work on metabolism and artificial intelligence in screening and trial design.
It does not mean Alzheimer's has been cured. Doctors can treat the disease earlier, measure risk more precisely and expand basic care's role. Until now, cost and invasive testing limited that role. For patients and families, waiting for severe symptoms is no longer the only clinical strategy available.
Dr María Isabel Tejeda González is an internist at Clínica Neleva.
