PET, MRI Identify What Increases Women’s Likelihood of Alzheimer’s

When it comes to the risk of developing Alzheimer’s disease, PET and MRI imaging results from a new study have revealed that women have four strikes against them.

In a research article published in the June 24 Neurology journal, investigators from Weill Cornell Medicine in New York, determined that women score worse than men on every measure used to assess their risk of having Alzheimer’s biomarkers.

“Our findings suggest that middle-aged women may be more at risk for the disease, perhaps because of lower levels of the hormone estrogen during and after menopause,” said lead study author Lisa Mosconi, Ph.D., director of the Weill Cornell Women’s Brain Initiative. “While all sex hormones are likely involved, our findings suggest that declines in estrogen are involved in the Alzheimer’s biomarker abnormalities in women we observed. The pattern of gray matter loss in particular shows anatomical overlap with the brain estrogen network.”

These findings, she said, contradict the widely held belief that women experience Alzheimer’s disease at greater rates because they live longer than men. This is the first study to look at how sex-specific risks can impact Alzheimer’s-related brain changes in midlife. Knowing more about these biomarkers is vital, her team emphasized, because existing evidence shows they can detect Alzheimer’s decades before the onset of clinical symptoms. 

Mosconi’s team used PET and MRI to evaluate and compare the differences between men and women in four areas:

• Volumes of both gray and white matter in the brain
• Levels of amyloid-beta plaques
• Glucose metabolization rate in the brain (an indicator of brain activity)

The investigators enrolled 121 participants -- 85 women and 36 men – with an average age of 52. Participants had no cognitive impairment, and they exhibited similar thinking and memory skills, thyroid function, Alzhiemer’s family history, vascular risk factors, and physical lifestyles.

Each participant underwent PET imaging with carbon-11-labeled Pittsburgh Compound B (PiB) to pinpoint any amyloid-beta plaques in the brain. FDG was used to identify the extent of any neurodegeneration, and structural MRI scans measured each participant’s gray and white brain matter. 

According to the results, women had worse scores than men across all four categories:

• 30 percent more beta amyloid plaques in their brains
• 22 percent lower glucose metabolism in the superior frontal gyrus, medial frontal gyrus, and inferior parietal lobule,
• 11 percent less average gray matter volume – 0.73 cm³ compared to 0.8 cm³ in men
• 11 percent less average white matter volume– 0.74 cm³ compared to 0.82 cm³ in men

Despite these lower scores, Mosconi’s team found women, including post- and perimenopausal women, did not demonstrate any reduced levels of cognitive performance compared to the male study participants. This result, they posited, suggests that biomarkers are more sensitive and can more accurately detect Alzheimer’s risk in individuals not showing symptoms than cognitive tests.

Mosconi pointed out that these results are applicable to healthy, middle-aged adults who do not have severe cerebrovascular or cardiovascular disease. More studies are needed to determine whether these results can be generalized.