Women experiencing or preparing for menopause need facts rather than fear-mongering, experts say, calling for further research into the prevalence of cognitive challenges such as brain fog.

Women typically enter menopause between 45 and 60 and perimenopause - which precedes it - can start in their 30s and last up to 10 years

Many women report varying degrees of forgetfulness, attention or concentration difficulties, as well as fogginess during this period.

In a landmark review, published in The Lancet Obstetrics and Gynaecology, researchers from the University of Melbourne, Monash University and University College London say there is a gap in knowledge about the prevalence and long-term impacts of brain fog and other cognitive symptoms.

There were no clear, evidence-based solutions to prevent or treat brain fog, University of Melbourne and Royal Women's Hospital professor Martha Hickey said.

"We don't even have a definition of what brain fog is and one person's brain fog experience would be different to what someone else is experiencing," she told AAP.

"It's a real gap in our understanding."

Brain fog could be a side-effect of sleep disturbances which can be common during menopause, but Professor Hickey said the lack of long-term data made it difficult to determine the cause.

"There is a lot of uncertainty (and) women are quite scared of menopause so the more symptoms that are accredited to it, the more fear," she said.

"What women need is consistent, evidence-based information because at the moment women get inconsistent information, largely from social media.

"To equip women to prepare, cope with and thrive in this period of their lives, because it's not all bad, we really need consistent information."

The research sets out key questions that general practitioners should be asking their patients.

These include questions about how concentration or memory is being affected, how long it has been happening for and how daily life has been impacted by these symptoms.

"GPs and clinicians have a really important role to play here in validating women's experiences of these cognitive symptoms during menopause, talking about potential causes as well as offering treatment options," study author and clinical neuropsychologist Caroline Gurvich said.

"We are still gathering evidence about whether hormone therapy can help cognitive symptoms (and) there are also evidence-based lifestyle changes that may be helpful in the short term as well as reducing the risk of later life cognitive decline," Professor Gurvich said

In 2025, the federal government announced it would open the tender process to develop national guidelines to improve health outcomes for women in diagnosis, treatment and care during menopause.