Frequent Flyer Beware: Jet Lag Is Bad for the Memory
Previous work by Cho and others has shown that long distance flights stimulate the body to produce a stress hormone called cortisol. While the flight attendants taking transatlantic flights less often had normal cortisol levels, those who crossed time zones more frequently had high cortisol levels in their saliva.
Over the long haul, Cho believes that elevated cortisol due to shifting time zones is responsible for both the loss of brain cells and the memory impairment. The higher the elevations in cortisol levels, the smaller the temporal lobe volumes on MRI.
To determine how long these effects last and to see whether they are reversible, Cho plans to study the women after they retire. Similar long-term effects of high cortisol on memory and on loss of brain cells have been reported in severe depression and in posttraumatic stress disorder.
This study is an interesting look at the possibility of permanent damage to the structure and functioning of the temporal lobe caused by a long-term disturbance of the body-clock, Rodolfo Costa, PhD, tells WebMD after reviewing the findings.
"It would ... be of major interest to investigate whether similar effects can be observed in people exposed to work-shift regimens," says Costa, a professor of biology at the University of Padova in Italy. Shift workers and even parents of young children may also have chronic sleep-deprivation and body clock disruption.
But Atkinson feels that the issue of shift work might be more complicated. Although night and day may be reversed for shift workers, this may not be as disruptive to the body clock as regular transcontinental flights, as there is at least a daily pattern to the disturbance.