KL and early-onset autosomal dominant Alzheimer disease: Lower klotho in women with chronically high stress suggests an interactive role for the psychosocial environment in systemic levels of a biological factor that influences longevity,3, 7, 25 brain function12, 26, 48 and body health.25 This is important because it establishes a link between life experience and levels of circulating klotho—in addition to known influences on its levels from genetic KLOTHO variation,12, 23 aging,28, 42 kidney disease49 and Alzheimer's disease.50