Cognitive, Not Bio, Markers Predictive of Cognitive Decline

Cognitive markers predict conversion of cognitive impairment to Alzheimer's better than biomarkers

THURSDAY, Sept. 8 (HealthDay News) -- Cognitive markers are more effective predictors of conversion from mild cognitive impairment to Alzheimer's disease than biomarkers, according to a study published in the September issue of the Archives of General Psychiatry.

Jesus J. Gomar, Ph.D., from the Benito Menni Complex Assistencial en Salut Mental in Barcelona, Spain, and colleagues investigated the discriminative utility of different classes of biomarkers and cognitive markers by assessing their ability to predict conversion from mild cognitive impairment to Alzheimer's disease. The Alzheimer's Disease Neuroimaging Initiative (ADNI) database was analyzed to study 116 patients with mild cognitive impairment who converted to Alzheimer's disease, and 204 patients who did not convert within a two-year study period. The predictive utility of 25 variables from all classes of markers, biomarkers, and risk factors were determined by logistic regression models and effect size analyses.

The investigators found that, in logistic regression models, which included variables from all classes of markers, two measures of delayed verbal memory and middle temporal lobe cortical thickness predicted conversion within a two-year period. Effect size analyses revealed that biomarkers had modest change scores for two years, but change in an everyday functional activities measure was substantially larger. Approximately 50 percent of the predictive variance in conversion from mild cognitive impairment to Alzheimer's disease was attributed to decline in scores on the Functional Assessment Questionnaire and Trail Making Test, part B.

"We demonstrated that cognitive markers were consistently significant and generally stronger predictors than biomarkers," the authors write.

Two authors disclosed financial ties with the pharmaceutical industry. One of the study authors receives royalties for use of a cognitive test battery in clinical trials. The ADNI database used in the study was funded by the pharmaceutical industry.

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