New York, Aug 29 (IANS): Women who are genetically predisposed to the risk of Alzheimer's are more susceptible to developing the disease during a critical 10-year span in their lives than men with similar genetic risks, researchers have found.

The findings showed that among women and men between ages 65 and 75 having one copy of ApoE4, women -- more than 10 years after the start of menopause -- were at increased risk compared with men.

The study contradicts the previously held view that women with one copy of Apolipoprotein E4 allele (ApoE4) -- the main genetic risk factor for late-onset Alzheimer -- were diagnosed with the disease 50 per cent more often than men with the same genetic profile.

The reasons that might underlie these sex differences could be linked to physiologic changes associated with menopause and estrogen loss, the researchers said in the paper published in the journal JAMA Neurology.

"Menopause and plummeting estrogen levels, which on average begins at 51, may account for the difference," said Judy Pa, Assistant Professor at the University of Southern California, Los Angeles.

For the study, the team analysed 27 research studies with data on nearly 58,000 participants, between the ages of 55 and 85, to determine how sex and APOE genotype affect the risks for developing mild cognitive impairment (MCI) -- often the transitional phase from cognitively normal ageing to dementia, and Alzheimer's.

Further, women also appeared to be at increased risk of developing Alzheimer's between the ages of 55 and 70 compared to men.

"Collectively, our findings, along with previous work, warrant further investigation into a likely complex set of risk factors with consideration of sex-specific treatments for cognitive decline and Alzheimer's disease," said Arthur W. Toga, from the varsity.

"For example, if women are at increased risk for AD at younger ages, it is plausible that treatments for women may need to be initiated earlier, especially in those who carry an APOE E4 allele."