A study published December, 2009 in the British Medical Journal reports that longer survival of 1,826 twins correlated with the “perceived age” of the subjects. Perceived age was significantly associated with survival, even after adjustment for chronological age, sex, and environment. The bigger the difference in perceived age within a pair, the more likely that the older looking twin died first.
The study began in 2001 and concluded in 2008. There are a variety of factors which are instrumental, including smoking status, body mass index, and sun exposure.
Physicians traditionally compare perceived and chronological age, and for adult patients the expression "looking old for your age" is an indicator of poor health. The study indicates that this practice, which has existed for centuries, is actually a useful clinical approach especially given that in a clinical setting perceived age is based on an array of indicators in addition to facial appearance. The next time someone says 'you look good for your age', make sure they know how old you really are.