NEW YORK, Jul 21 (Reuters Health) -- Hormones influencing childhood intelligence may also help determine the age at which a woman reaches menopause, according to researchers.
Findings from a long-term study of British women suggest that "the higher the cognitive (intelligence) score at age 8, the later the age at menopause," according to Dr. Marcus Richards and colleagues at University College London, UK. Their report is published in the July 22nd issue of the journal Neurology.
The researchers gave 1,572 UK women born in 1946 a battery of intelligence tests as they reached 8, 11, 15, 26, and 43 years of age. They then recorded the menopausal status of each woman at 50 years of age.
According to the investigators, the "cognitive function at ages 8 and 11 years was strongly associated with timing of the natural menopause."
Those women who achieved low scores on childhood intelligence tests reached menopause at an earlier age than those with higher scores, the authors report. "By age 50 years, 26% of women scoring in the lowest third of the cognition score had reached menopause," they point out, "compared with 18% in the highest third." This association remained strong even after adjustment for other factors such as number of offspring, smoking, social class, and education.
In contrast, the authors found little association between age at menopause and scores on intelligence tests conducted during adulthood.
How might childhood intelligence be tied to the timing of menopause? Levels of estrogen, produced by the ovaries, may be the link. "One possible explanation for this connection is the role that estrogen and other steroids have in programming the nervous system during fetal development," Richards explained in a statement issued by the American Academy of Neurology.
Scientists have speculated that estrogens influence the development of the cerebral cortex and hippocampus, areas of the brain that play major roles in higher-thought processes and memory.
A fall in estrogen production by the ovaries is characteristic of menopause. The researchers speculate that the brain may play a role in timing this drop in estrogen.
"Since estrogen plays a role in brain development early in life, measuring mental ability may give us a clue about the brain's role in reproductive aging," said Richards.
The UK study subjects are scheduled to undergo further cognitive testing as they reach 53 years of age. The researchers hope that the results of these tests will "help determine whether women who come early to menopause are at (higher) risk for functionally significant cognitive decline" compared with women who go through menopause at a relatively later age.
SOURCE: Neurology 1999;53:308-314.