An Exception to the General Rule
Ouroboros looks at a rare example of a treatment that extends life span but shortens healthspan in flies: "One of the central precepts of biogerontology is that meaningful lifespan extension will be concomitant with extension of the 'healthspan', i.e., the vigorous part of life - life that is, for lack of a better phrase, worth living. This relationship is borne out both in nature (where longer-lived organisms also have longer healthspans) and in the laboratory, where genetic and pharmaceutical manipulations increase longevity also increase the duration of healthy life ... Because of the importance of this assumption, we need to be on the lookout for counterexamples, such as the one provided by a recent study ... The authors show that lamotrigine, an anticonvulsant medication already shown to extend lifespan in the worm C. elegans, also has longevity benefits in the fly - but at an apparent cost to healthspan. ... the existence of exceptions to the general case underscores the importance of vetting each candidate longevity enhancement therapy for its effects on healthspan, before rushing into further development."
Link: http://ouroboros.wordpress.com/2009/05/29/extending-lifespan-while-shortening-healthspan/