Är detta anledningen till att Alzheimers är vanligare hos kvinnor?

The study, presented at the Alzheimer's Association International Conference in LA, found that the protein, tau, showed a larger brain-wide accumulation in women than in men due to an accelerated brain-wide spread. A growing body of evidence suggests that the protein spreads through the brain like an infection. It travels neuron to neuron, turning other proteins into abnormal tangles and killing brain cells.

Alzheimers sjukdom is the most common type of demens, a progressive condition which affects brain function, including memory. It is incurable and the cause is not known, although we do know that there is progressive damage to the cerebral cortex in the brain which prevents cells from functioning as they should.

Alzheimer's affects around one in 14 people over 65 and one in six people over the age of 80. This equates to 850,000 people in the UK. Women are more likely than men to develop Alzheimer's, with women accounting for around 65% of cases of dementia in the UK.

The research looked at PET scans of healthy individuals and those with mild Alzheimer's. They modelled the spread of tau using a technique called graph theory analysis.

Sepi Shokouhi, lead investigator of the study and assistant professor of Psychiatry and Behavioural Sciences at the Center for Cognitive Medicine at Vanderbilt University Medical Center, described the study as "kind of like reconstructing a crime scene after a crime. You weren't there when it happened, but you can determine where an intruder entered a house and what room they entered next. The graph analysis does something similar to show how tau spreads from one region to another".

The results showed that tau networks are different between the sexes, with women having more 'bridging regions' which connect the various parts of the brain. This may allow tau to spread more easily and quickly between regions, putting women at greater risk for Alzheimer's. More studies are needed to prove this connection, but if successful, could point to the need for more sex-specific treatment and prevention approaches for women at risk of Alzheimer's.

Shokouhi believes that this research could contribute to understanding of how Alzheimer's develops: "Understanding how different biological processes influence our memory is a really important topic. Sex-specific differences in the brain's pathological, neuroanatomical and functional organisation may map into differences at a neurobehavioural and cognitive level, thus explaining differences in the prevalence of neurodegenerative disorders and helping us develop appropriate treatments."

The research was presented at the Alzheimer's Association International Conference in LA.