Low premorbid IQ effects biomarker-cognition relationships: A pilot study

Previously, we found that plasma levels of phosphorylated tau 181 (p-tau 181), total tau (T-tau), and neurofilament light (NfL) differ significantly based on premorbid intellectual ability (pIQ).

This study examines how these biomarkers are associated with cognitive outcomes across pIQ and racial/ethnic groups.

Participants from the Health & Aging Brain Study-Health Disparities (HABS-HD) were categorized as having low (z ≤ -2.00) or average (z = 0.00 ± 1.00) pIQ using word reading scores. Regression analyses were conducted.

Among participants with low pIQ, elevated plasma p-tau 181 was more strongly associated with worse episodic memory. In stratified analyses, NfL, p-tau 181, and t-tau were differentially and inconsistently associated with cognitive outcomes, with varying strength based on pIQ grouping.

A one-size-fits-all approach to biomarker-cognition associations interpretation may overlook important individual differences driven by pIQ. These exploratory analyses provide preliminary evidence to support future studies aimed at validating cognitive stratification in biomarker interpretation and interventions for individuals with low pIQ.