Australian researchers have identified lifestyle factors that impair women's brain performance as early as age 45.
A joint study from The University of Queensland, the University of New South Wales and Flinders University of South Australia shows certain lifestyle behaviours like smoking, excessive drinking and physical inactivity are linked to negative brain functions in women.
Supported by grants from the National Health and Medical Research Council and the Royal Brisbane and Women's Hospital Foundation, the eight-year study involved 489 Brisbane middle-aged and older women who were recruited from 2001.
Professors Gerard Byrne from the UQ School of Medicine and Nancy Pachana from the UQ School of Psychology led the study.
Professor Pachana said the effect these lifestyle factors could have on cognitive performance occurred much earlier than expected.
"Although the average person might believe cognitive decline usually occurs later in life, research suggests significant declines in all aspects of cognitive performance may begin as early as age 45 in women," Professor Pachana said.
"In our study we were able to detect independent and consistent effects across time for smoking, drinking, and physical activity on five measures of cognitive function," she said.
She said objective thinking and memory tests were administered on three occasions over eight years and each time results showed smoking appeared to have impaired cognitive function.
"Moderate drinking and high physical activity levels offered protective effects over time, compared to not drinking and low levels of physical activity," Professor Pachana said.
"These effects remained after adjustments were made to take account of the varying ages and levels of education of the women in the study, as well as adjustments for differences in health such as hypertension.
"Effects remained for light to moderate drinkers even after adjusting for physical activity levels.
"Current smokers performed worse than past smokers, who in turn performed worse than those who had never smoked."
If the women in the study engaged in increasing intensities of physical exercise, rather than just quantity of physical activity, they were less likely to experience declines in thinking.
"Future studies might aim to determine longer-term outcomes across time of cognitive change as influenced by lifestyle behaviours such as exercise," Professor Pachana said.