Combined Testing May Detect Alzheimer's Disease Earlier Than Standard Methods

A study in Biological Psychiatry found that a combination of non-invasive, low-cost cognitive measures may help determine people who are at risk for progressing to Alzheimer's disease, reports Healio . Although amyloid-beta levels in the brain become abnormal long before severe cognitive impairments manifest, a growing body of evidence suggests subtle cognitive changes may arise before amyloid-beta exceeds the threshold for abnormality. The researchers considered the association of baseline cognitive composites called the Preclinical Alzheimer Cognitive Composite and the Alzheimer's Disease Neuroimaging Initiative with progression to amyloid-beta positivity in 292 nondemented, amyloid-beta-negative subjects. Later studies looked at the effects of subthreshold pathology using continuous cerebrospinal fluid biomarker levels. The team found a link between poorer baseline performance on both cognitive measures and elevated odds of progression. More abnormal levels of subthreshold amyloid-beta and baseline cerebrospinal fluid phosphorylated tau correlated with higher odds of progression to amyloid-beta positivity. "There is often a focus on finding the single best cognitive test to use in detecting Alzheimer's disease, but . . . we think that the increased sensitivity gained from combining multiple tests is well worth the time and effort needed to collect them," concluded the University of California, San Diego's Jeremy A. Elman.