First AD

Second AD

Attempts to explain the aging process at the cellular level have identifiedtwo main culprits - intrinsic aging and photoaging. "When referringto the skin," said Mina Yaar, M.D., "it's important to differentiatebetween intrinsic or chronologic aging that comprises the clinical, histologic,and physiologic changes in sun-protected skin, and photoaging, defined asthe clinical, histologic, and physiologic changes in habitually sun-exposedskin." She is professor of dermatology at Boston University Schoolof Medicine. Dr. Yaar addressed the topic of molecular mechanisms in agingand photoaging at the AAD annual meeting.