Hormone replacement therapy patches used to reduce symptoms of the menopause may preserve the brain and protect against Alzheimer’s, research suggests.

Over a period of seven years, treatment with the skin patches was associated with less age-related shrinkage of part of the brain involved with memory, thinking and reasoning.

Women whose brains responded in this way were also less likely to have a key hallmark of Alzheimer’s disease, scientists found.

Their brains contained fewer sticky clumps of beta-amyloid, a toxic protein fragment believed to help trigger the death of neurons.

But hormone replacement therapy (HRT) had no impact on scores in thinking and memory tests.

Lead researcher Dr Kejal Kantarci, from the Mayo Clinic in Rochester, US, said: “We found that one form of menopausal hormone therapy taken soon after menopause may preserve brain structure in the portion of the brain responsible for memory and thinking skills.

“It may also reduce the development of amyloid plaques that can build up and lead to memory loss.”

For the study, the researchers recruited 75 healthy women with an average age of 53 who were between five months to three years past the menopause.

Of those, 20 took a pill form of HRT, 22 received oestrogen-releasing skin patches, and 33 were given a “dummy” placebo treatment that was either a pill or a patch. Treatment was continued for four years.

Scans showed that women using the active patches maintained volume in the dorsolateral prefrontal cortex brain region over the full period of the study, extending beyond the end of treatment.

Changes in the brain were also seen during therapy with oestrogen pills, but they ceased when the treatment stopped.

The findings are published in the journal Neurology.

Dr Kantarci said: “More research is needed to determine the biological reasons behind brain changes during menopausal hormone therapy.

“Future research is also need to better define just how the different hormonal products, pills versus skin patches, affect the brain.”