Extreme stress and amnesia
four days of extreme stress, as experienced by war refugees, is all that it may take to significantly impair memory. Some us psychologists have reached this conclusion. Moreover, they have traced the phenomenon down to a single hormone.
Psychologists have known for long that prolonged stress can cause amnesia or affect the memory adversely. Though scientists have been very uncertain about what causes such effects, many suspect the involvement of the hormone cortisol. The hormone is active in the brain in conditions of stress. Now, John Newcomer and his colleagues at Washington University in St Louis, Missouri, usa , have come out with findings that shed new light on the issue ( Archives of General Psychiatry , Vol 56, p527).
The researchers gave 50 volunteers a daily dose of cortisol pills for four days. While some were given either a low dose or a placebo, others were given as much cortisol as can be found in the blood of a person fleeing a burning village in war. Before they started taking the doses of cortisol, all three groups scored equally well in memory tests. There was no significant change after one day. But by day four, people who had been administered the highest doses of the hormone started manifesting more adverse effects than others when they were asked to recite a short paragraph that had been read to them 30 minutes earlier. Six days after the doses of cortisol were discontinued, the volunteers started recording normal memory again.
Says Newcomer: "The good news is that it takes several days of exposure to produce this effect on the memory.' Moreover, milder forms of stress, such as slogging for an examination, does not produce such high levels of the hormone in most people, the researcher points out.
James Bremmer of Yale University in New Haven, Connecticut, usa , who conducts research on stress and memory, says the report is the first to clearly link the effect on memory within the body's normal range of cortisol levels. The results may have implications for more severe memory loss as well, he points out, adding, "Amnesia has a biological base, and cortisol is a good candidate for the cause.