Hormone replacement therapy is linked to brain shrinkage in women, according to two new studies, which suggest that these patients may be at greater risk for dementia or related symptoms.
For one study, researchers conducted MRI brain scans of 1,400 women between the ages of 71 and 89.
They found that women who had taken the hormone estrogen, either with our without the hormone progestin, had smaller brain volumes in areas related to memory and thinking, compared to women who took a placebo.
Specifically, researchers found that the brain volume of women who took estrogen was 2.37 cubic centimetres lower in the frontal lobe and .10 cubic centimetres lower in the hippocampus.
Both of these regions are involved in thinking and memory skills, and loss of volume in the hippocampus is a known risk factor for dementia.
The findings were more prevalent among women who may have already started exhibiting memory problems before they began taking hormones, according to study author Susan Resnick.
"This suggests that estrogen may adversely affect thinking skills among women whose brains may already be beginning a neurodegenerative disease process," Resnick, of the National Institute on Aging in Baltimore, said in a statement.
The findings are published in the journal Neurology.
Previous research has shown that taking estrogen, with or without progestin, can increase the risk of developing dementia or thinking and memory complications, in women over the age of 65.
However, the second study found that taking hormone therapy did not increase the volume of small vascular lesions in the brain, known as silent strokes, which are thought to be a risk factor for dementia.
Together, the two studies suggest that the negative effects of hormone therapy on cognitive decline may have less to do with vascular lesions and more to do with brain volume loss.
