Knowledge of blood test results enables primary care physicians to diagnose Alzheimer's disease with essentially the same accuracy as specialists, a major step toward expanding access to an accurate diagnosis for millions of patients, suggests new data reported for the first time at the Alzheimer's Association International Conference (AAIC) 2026 in London and online.

In one of the first real-world studies of its kind, which included more than 1,300 patients and 165 physicians, researchers found that a blood-based biomarker test significantly improved the accuracy of Alzheimer's diagnosis in both primary and speciality care settings. The test measures amyloid beta and phosphorylated tau, both of which are abnormal brain proteins linked to Alzheimer's disease.

In a direct comparison among primary care patients, primary care physicians achieved nearly the same diagnostic accuracy as dementia specialists, around 90 per cent for both. After reviewing the blood test results, the physicians changed diagnoses in about one-third of patients and changed their plans for future care and examinations for more than half of patients.

"We wanted to find out whether a simple blood test for Alzheimer's changes how doctors actually diagnose and manage their patients in everyday clinical care," said Sebastian Palmqvist, M.D., PhD, lead author of the study, neurologist and associate professor of neurology at Lund University, Sweden. "Accurate Alzheimer's diagnosis has largely been limited to specialist settings. Our findings show that this blood test could bring that level of accuracy into primary care, where most patients are first seen, closing the gap between primary care and speciality care."

The blood test was most useful in primary care for ruling out Alzheimer's, Dr Palmqvist said. Primary care clinicians remained cautious about using it to diagnose the disease, preferring to send their patients to a specialist for confirmation, as is appropriate, he noted.