According to the experiment done by Clark et al. healthy elderly subjects do not excrete free water as efficiently as younger ones do. In particular, elderly subjects with a previous history of TIH have impaired urinary dilution capacity, and hence, increased susceptibility to TIH. Among the explanations, blunted prostaglandin synthesis is an attractive possibility and could result from aging or propensity among the elderly for polypharmacy, including non-steroidal anti-inflammatory agents.