Igf-I and longevity

Recent animal studies have demonstrated evidence of the involvement of insulin and insulin-like growth factor (IGF)-I signalling in the control of ageing and longevity. Disruption of insulin/IGF-I signalling pathways significantly extends lifespan in several animal models. Similarities among these signalling pathways in animals and humans raise the possibility that modifications in the IGF-I signalling system could also extend lifespan in humans. However, in contrast to the findings in animal studies, reduced IGF-I activity in humans is not associated with longevity. In humans, low IGF-I activity is even associated with an increased risk of developing cardiovascular disease and diabetes. High IGF-I activity in humans is associated with an increased risk of developing cancer. In addition, genetic predisposition and lifestyle play a major role in determining age-associated disease. For each individual there is probably a specific optimal 'setpoint' for the insulin/growth hormone/IGF-I axis which co-determines survival.