Sex and gender differences in dementia

Neurological Disorders and Women's Health: Contribution of Molecular Neuroimaging Techniques

Sex differences in brain physiology and the mechanisms of drug action have been extensively reported. These biological variances, from structure to hormonal and genetic aspects, can profoundly influence healthy functioning and disease mechanisms and might have implications for treatment and drug development. Molecular neuroimaging techniques may help to disclose sex's impact on brain functioning, as well as the neuropathological changes underpinning several diseases. This narrative review summarizes recent lines of evidence based on PET and SPECT imaging, highlighting sex differences in normal conditions and various neurological disorders.

Is the female sex associated with an increased risk for long-term cognitive decline after the first-ever lacunar stroke? Prospective study on small vessel disease cohort

Background

Sex is a significant determinant of survival and functional outcome after stroke. Long-term cognitive outcome after acute lacunar stroke in the context of sex differences has been rarely reported.

Methods

A cohort of small vessel disease (SVD) patients presenting with first-ever acute lacunar stroke and normal cognitive status has been evaluated 4 years after the qualifying event for the presence of cognitive impairment (CI) with a comprehensive neuropsychological battery. Differences in baseline clinical and neuroimaging characteristics were compared between sexes in relation to cognitive status.

Results

A total of 124 female and 150 male patients were analyzed. No difference was detected between the groups regarding age (p = 0.932) or frequency of common vascular risk factors (p > 0.1 for all). At the baseline assessment, women had more disabilities compared to men with a mean modified Rankin scale (mRS) score of 2.5 (1.5 in men, p < 0.0001). Scores of white matter hyperintensities (WMH) of presumed vascular origin and a total number of lacunes of presumed vascular origin on brain MRI were higher in women compared to men (p < 0.0001 for all). As many as 64.6% of patients had CI of any severity on follow-up, women more frequently (77.4%) than men (54.0%; p < 0.0001). Univariate logistic regression analysis showed that female sex, higher NIHSS and mRS scores, presence of depression, and increasing WMH severity were associated with an increased risk for CI. Multivariate regression analysis indicated that only depression (OR 1.74, 95%CI 1.25-2.44; p = 0.001) and WMH severity (OR 1.10, 95%CI 1.03-1.17; p = 0.004) were independently associated with the CI.

Conclusion

At the long-term follow-up, women lacunar stroke survivors, compared to men, more frequently had CI in the presence of more severe vascular brain lesions, but this association was dependent on the occurrence of depression and severity of WMH, and could not be explained by differences in common vascular risk factors.

Sex Differences in the Association Between Body Mass Index and Dementia Risk in Community-Dwelling Japanese People Aged 40-74 Years

BACKGROUND

The association between body mass index (BMI) and dementia risk is heterogeneous across age groups and might be influenced by sex.

OBJECTIVE

This study aimed to clarify sex differences in the association between BMI and dementia risk in community-dwelling people.

METHODS

This cohort study with an 8-year follow-up targeted 13,802 participants aged 40-74 years at baseline in 2011-2013. A self-administered questionnaire requested information on body size, including height, weight, and waist circumference (the values of which were validated by direct measurement), socio-demographics, lifestyle, and disease history. BMI was calculated and categorized as < 18.5 (underweight), 18.5-20.6 (low-normal), 20.7-22.6 (mid-normal), 22.7-24.9 (high-normal), 25.0-29.9 (overweight), and≥30.0 kg/m2 (obese). Incident cases of dementia were obtained from the long-term care insurance database. A Cox proportional hazards model was used to calculate multivariable-adjusted hazard ratios (HRs).

RESULTS

The mean age of participants was 59.0 years. In men, higher BMI was associated with lower dementia risk (fully-adjusted p for trend = 0.0086). In women, the association between BMI and dementia risk was U-shaped; the "underweight," "low-normal," and "overweight" groups had a significantly higher risk (fully-adjusted HR = 2.12, 2.08, and 1.78, respectively) than the reference ("high-normal" group). These findings did not change after excluding dementia cases which occurred within the first four years of the follow-up period.

CONCLUSION

Overweight/obese women, but not men, had an increased risk of dementia, suggesting that sex differences in adiposity might be involved in the development of dementia.