A look at sex differences in the neuropsychological deficits of Alzheimer disease.
Women have a harder time of it than men when Alzheimer disease (AD) strikes, according to a multicenter team of investigators from the University of Central Missouri, Medical College of Wisconsin, and University of Kansas Medical Center. That is, women with AD tend to display greater neuropsychological deficits in relation to semantic fluency and memory and the ability to identify and name objects on sight (confrontation naming) than their male counterparts.1
The data have heretofore been mixed: some studies show poorer performance among women regarding verbal fluency and memory, and others show no difference or an advantage among women. In the current study, investigators sought to clarify the evidence, noting that identifying sex differences in AD may be useful in designing cognitive interventions for dementia.
The investigators compared test scores of 86 men (mean age, 71 ± 7.6 years) and 96 women (mean age, 73 ± 8.5 years) with AD in relation to immediate and delayed prose memory, verbal fluency, semantic fluency, semantic memory, and confrontation naming. Mean duration of illness was about 2 years for both groups, and the researchers designed the study such that global cognitive functioning between groups was comparable. Mattis Dementia Rating Scale scores were 89.27 ± 29.80 for men and 90.86 ± 30.20 for women.
Prose memory was evaluated using the Logical Memory I and II subtests of the Wechsler Memory ScaleâRevised (WMSR), and semantic memory was evaluated using the Information subtest of the Wechsler Adult Intelligence ScaleâRevised. Verbal (lexical) and semantic fluency abilities also were tested. The former was measured via the FAS test in which participants are asked to name as many words as they can that start with the letters F, A, and S, with a 60-second time limit given for each letter. Semantic verbal fluency was tested by having the participant name as many animals as possible within a 60-second period. For confrontation naming, the Boston Naming Test was used. The effect size was presented as Cohen’s d, with multivariate analysis of covariance applied to group comparisons with significant t-ratios.
In this study, significantly better scores were seen among men compared with women in relation to immediate prose memory (d = 0.49), semantic verbal fluency (d = 0.56), semantic memory (d = 0.49), and confrontation naming (d = 0.60). Men and women performed similarly on the remaining tests. When age, education, and duration of disease were controlled for, however, sex differences were seen in regard to semantic memory (P = .006), semantic fluency (P = .007), and confrontation naming (P = .004) but not prose memory.
The study adds further insight to existing studies that have shown that although older cognitively healthy women are known to outperform age-matched, healthy men on a number of neuropsychological measures, circumstances are reversed in the AD population. In this study, women with AD demonstrated greater impairment compared with their male counterparts in relation to 3 of 6 neuropsychological measures: semantic verbal fluency, semantic memory, and confrontation naming.
A few caveats
The researchers noted, however, that some tests given may lead to misleading results. For example, in relation to semantic verbal fluency, it has been hypothesized that semantic fluency is only as good as the test-taker’s semantic knowledge base2; men may have performed better in this study simply because they are more familiar with animals as a category than are women. The researchers argued that parity regarding neurocognitive tests is needed to hone accuracy about perceived differences between men and women with AD. They concluded that further research into sex-specific cognitive differences in patients with AD would be worthwhile to better understand cognitive functioning of individual patients and to design treatment plans that take sex differences in AD into consideration.
“Approximately two thirds of Americans with AD are women, and in less than 50 years, the number of AD cases will be approximately 21 million,” corresponding author David Kreiner, MD, Professor and Chair of the Department of Psychological Science at the University of Central Missouri in Warrensburg, told Psychiatric Times. “The situation will hopefully prompt clinical researchers to develop gender-specific assessments and interventions.”
1. Ryan JJ, Umfleet LG, Kreiner DS, et al. Neuropsychological differences between men and women with Alzheimer’s disease. Int J Neurosci. 2017 Sep 19:1-19. [Epub ahead of print]
2. Monsch AU, Bondi MW, Butters N, et al. Comparison of verbal fluency tasks in the detection of dementia of the Alzheimer’s type. Arch Neurol. 1992;49:1253-1258.