University of Edinburgh (Scotland) researchers have shown how two receptors in older brains react to cortisol, the stress hormone, which has been linked to increasing forgetfulness as we age. Whereas one brain receptor was activated by low levels of cortisol, which helped memory, once levels of the stress hormone were too high they spilled over onto a second receptor – which consequently activated brain processes that contribute to memory impairment. The researchers are currently investigating a new chemical compound which blocks an enzyme - 11beta-HSD1 - that is involved in producing stress hormones within cells. They hope this could be used to develop a drug treatment to slow the normal decline in memory associated with aging or even improve memory in the already very old.