APA Dictionary of Psychology

any disruption of the gradual structural and immune changes that occur with the passage of time, resulting in premature aging and increased probability of early death. An example is progeria (or Hutchinson–Gilford progeria syndrome), a very rare inherited disorder in which children age extremely rapidly and typically die of a heart attack or stroke between the ages of 10 and 15 years. Another example is adult progeria (or Werner syndrome), with an onset occurring before the age of 30 and an average life expectancy of 20 years from diagnosis; patients typically die of atherosclerosis or some form of cancer.