Do Women With Alzheimer’s Disease Demonstrate Greater Cognitive deterioration?

Abstract

561 ISSN 1758-2024 10.2217/NMT.12.64 © 2012 Future Medicine Ltd Neurodegen. Dis. Manage. (2012) 2(6), 561–564 Two-thirds of patients diagnosed with Alzheimer’s disease (AD) are women. Of course, women have a greater longevity, but remain disproportionally prone to AD even after adjusting for their longer life expectancy. Much less attention has been paid to sex differences in the neurocognitive profiles of AD patients, and, in particular, evidence showing that women fare much worse than men cognitively. Remarkably, few studies report comparisons of neurocognitive performance in men and women with AD. Our recent meta-analysis identified just 15 published studies presenting data for men and women with AD (involving a total of 828 men and 1238 women) [1]. Significant and highly consistent male advantages emerged across every cognitive domain examined: episodic memory (Cohen’s d effect size [d]: -0.17; 95 CI: -0.33 to -0.01); semantic memory (d: -0.25; 95 CI: -0.42 to -0.07); verbal (d: -0.27; 95 CI: -0.37 to -0.16); and visuospatial (d: -0.24; 95 CI: -0.43 to -0.05) tasks. Although the effect sizes are small, this is unsurprising given the reduced levels at which most AD patients are cognitively functioning; and to overturn them would require 15 negative studies for memory, 114 for verbal ability, 26 for spatial and 28 for semantic ability. Indeed, of the 52 effect sizes we calculated, 94% (49/52) showed women exhibiting worse performances compared with men. Furthermore, moderator regression analyses demonstrated age, education and dementia severity (as measured by mini-mental state examination) did not significantly predict the male advantage, therefore it cannot be attributed to these particular confounds. Differences in the neurocognitive profiles of healthy men and women are ubiquitous, with verbal and spatial processing advantages for women and men, respectively, probably being the most common. In their large meta-analysis, Hyde and Linn derived 120 effect sizes for verbal task performance and found that women outperformed men in 75% of the studies – although the effect itself is modest (d: 0.11) [2]. Turning to visuospatial ability, in a meta-analysis of 286 studies spanning 50 years Voyer et al. confirms that men significantly outperform women: with a large effect for mental rotation (d = 0.73) and a medium effect for spatial perception (d = 0.44) [3]. Crucially, these sex differences persist into old age, with healthy