IS AGEING A DISEASE?Aging is often described as a risk factor for disease. Indeed, the risk for hundreds of diseases, the so-called age-related diseases, is increased with age and some of these diseases (such as Alzheimer's disease) never occur in young people. I and others have argued that aging itself should be called a disease. Interestingly, aging has been described as a 'disease complex' in the older literature (Perlman, 1953). But can something that increases the risk for disease (a risk factor) be a disease in itself? The answer is undoubtedly yes. Take for example diabetes which is a disease that also increases the risk for various other diseases such as diabetic nephropathy, retinopathy, neuropathy, atherosclerosis, and various cancers. Or the "accelerated aging" disease Hutchinson-Gilford Progeria Syndrome (HGPS) that increases the risk for heart disease.