Brain mechanical properties predict longitudinal cognitive change in aging and Alzheimer's disease.

Age-related cognitive decline is a complex phenomenon that is influenced by various neurobiological processes at the molecular, cellular, and tissue levels. The extent of this decline varies between individuals and the underlying determinants of these differences are not fully understood. Two of the most prominent signs of cognitive decline in aging are the deterioration of episodic memory, which is a hallmark of Alzheimer's disease (AD), and the nearly always accompanying atrophy of the medial temporal lobe. Both cross-sectional and longitudinal studies have consistently demonstrated the strong relationship between these two, however, recent advanced imaging techniques have shown promise for predicting cognitive decline earlier than atrophy measures. In this study, we investigate the value of brain biomechanical properties, specifically in the medial temporal lobe, for predicting global cognitive decline along the normal aging and AD spectrum. Our results indicate that the medial temporal stiffness significantly predicts future cognitive decline beyond that achieved by measures of atrophy and amyloidosis. Measures of brain biomechanical properties may provide valuable prognostic information to enable more efficient study design and evaluation of potential interventions.