Exercise to Improve Brain Health in Older African Americans

The goal of this clinical trial is to test the effects of different types of exercise on brain health and Alzheimer's risk in older African Americans. Specifically, the main question\[s\] it aims to answer are: * What is the effect of a Cardio-Dance Fitness (CDF) vs. a Strength, Flexibility, and Balance (SFB) intervention on a cognitive marker of Alzheimer's risk, generalization? * What is the effect of the CDF vs. SFB intervention on a fMRI biomarker of Alzheimer's, neural flexibility, and do improvements in neural flexibility mediate improvements in generalization? * Do ABCA7 genotypic variations moderate the efficacy of the CDF vs. SFB intervention for reducing Alzheimer's risk? Participants will undergo-- at baseline and post-test-- health assessments, cognitive tests, and structural and functional magnetic resonance imaging (fMRI), and a blood-draw to assess Alzheimer's risk biomarker levels.