WASHINGTON: A woman's hormones affect specific parts of the brain called the reward pathway, researchers said on Monday in a finding that could offer insight into treating drug abuse and mood disorders.

A study of women playing an imaginary slot machine game showed their brain responses changed in anticipation of a payout depending on the phases of their menstrual cycles.

This might help explain other studies that show women get a bigger kick from cocaine and amphetamines during one phase of the fertility cycle and perhaps why women are less vulnerable to schizophrenia than men are, the researchers said.

"This demonstrates for the first time that female ... hormones affect the reward system in very specific ways during particular parts of the cycle," said Karen Berman of the US National Institute of Mental Health.

"It is interesting to speculate that this may have evolutionary advantages and may affect behaviours that have been shown in other studies to also be affected by cycles."