Tuesday, 13 Jan, 2009 Health & Fitness

According to a new study, the oestrogen hormone therapy, which is used to treat a number of symptoms of menopause, contracts women's brains.

The research showed that elderly women, who participated in the clinical trial initiated by Women's Health Initiative and took oestrogen pills, registered a tiny decrease in the size of two brain areas that play an important role in forming and recalling memory compared to women who were on a placebo.

The lead researcher, Susan Resnick, who works as a clinical researcher at the National Institute of Aging in Baltimore, Maryland, said that the brain's shrinking could explain earlier accepted links between Hormone Replacement Therapy and dementia. The most probable explanation had been tiny strokes that interrupted the supply of blood to the brain. However, one of the recent studies found that patients on HRT had no more tiny brain lesions than women on a placebo. The lead researcher of the study was Laura Coker, who works as an epidemiologist at Wake Forest University Baptist Medical Center, located in Winston-Salem, North Carolina.

Two reports that observed volunteer patients from the Women's Health Initiative were unable to find what cause the shrinkage of the brain. In 2002 and 2004 doctors decided to stop the Women's Health Initiative research because preliminary results showed that oestrogen hormone therapy raised the risk of heart attacks, the development of breast cancer and strokes in elderly patients. A research carried out later showed that HRT also increased the risk of dementia in women over 65.

In order to confirm their discovery, the teams of Resnick and Coker decided to observe 1,400 women, who were asked to undergo a magnetic resonance brain scan. With its help scientists estimated the volume of the brain and the dimensions of microscopic lesions. The volunteers included patients who took either oestrogen therapy for about 18 moths and those who took a combined oestrogen and progestin therapy or placebo for about 36 months. The average age of the study participants was slightly over 77.

Researchers found that patients who took either form of HRT had smaller brain than those on placebo. Their brain was several cubic centimeters smaller in size. The therapy had the most significant impact on hippocampus (an area in the brain involved in the formation of memories) and frontal lobe (an area in the brain involved in memory recall), reports BBC News.

"We found the negative affects on these brain volumes were greatest on women who entered the trial with the lowest cognitive function," said one of the lead researchers.

Scientists look forward to carry out a new study in order to see whether the brain continues to shrink. Now, however, Coker warns that women older than 65 should not begin HRT due to the risks involved. At the same time she says that women in their 40s and 50s should not draw back from hormone therapy if necessary. In case these women have menopausal symptoms they should consult their doctor and decide whether to continue taking hormone therapy.