Martin's major research focus involved using genetic approaches to elucidate the pathobiology of aging and age-related diseases. Martin's work provided important insights into multiple topics in the field of geroscience. His group conducted genetic linking studies identifying loci associated with familial forms of Alzheimer's disease, a discovery that led to the recognition of amyloid beta (Aβ) in the pathology of that disorder. Martin's group separately identified the genetic defect causing the aging disease Werner syndrome, and its underlying contributory mechanisms to the disorder. His studies provided the first evidence that epithelial cells from arteries, especially from parts that develop severe atherosclerosis, have limited potential to divide. He and colleagues demonstrated that senescent cells cannot be returned to a replicative state when their cytoplasm is combined with cytoplasm from normal, young cells. Martin's laboratory was the first to demonstrate the accumulation of somatic mutations in human epithelial cells during the aging process. His later research used genetic engineering in mice to elucidate mechanisms of aging and Alzheimer's disease.