The difficulty in doing clinical trials for drugs to cure a disease like AIDS that takes many years to develop has led to trying to find surrogate markers to allow clinical trials over shorter time periods. For AIDS the best-known surrogate marker has been CD4 counts. This article discusses the difficulties of getting reliable predictions using a particular marker like the CD4 counts and the search for other markers. Overturning Received Wisdom. An account of two papers in this issue of Science that challenge the theory that the death rate in monotone increasing.
Gompertz law claims that in humans the death rate increases exponentially.
It has been roughly verified for humans but scientists have pointed out that it is hard to check for very old people because of limited data. These studies carried out with millions of fruit flies under quite controlled conditions suggest that Gompertz law is not appropriate for fruit flies and may well not be correct for humans. The Port Pirie Cohort Study. This study shows that exposure to lead in early childhood can cause identified intellectual defects in children even after a seven year period.