Psychosocial interventions in Alzheimer's disease and amnestic mild cognitive impairment: evidence for gender bias in clinical trials

Abstract

Background: Alzheimer's disease (AD) affects twice as many women as men. Gender differences in symptom profile, living conditions, coping style and response might affect the outcome of psychosocial interventions (PSIs).

Objectives: Our aim was to review gender differences in the available high-quality phase III trials on PSI in AD and amnestic mild cognitive impairment (aMCI) by considering the gender ratio in the investigated samples.

Design: Randomized controlled trials published in 2000-2012 were stepwise analyzed by statistically testing the representativeness of the gender ratio and examining reported gender differences.

Results: Forty-five studies (62% of 73 studies) reported gender ratios for each subsample and were included. In these studies, females were underrepresented in the control groups. In the 14 studies (19%) reporting analyses of gender differences, women were underrepresented in both intervention and control groups. However, in the six studies (8%) reporting significant gender differences in outcome, gender distribution was in accordance with prevalence rates.

Conclusion: Current evidence is insufficient for reliable conclusions on gender differences in PSI outcome in AD and aMCI, as 81% of the available clinical trials either not reported the gender ratio of their samples, or underrepresent females. Further research is needed addressing gender differences, and clinical trials should routinely control for gender bias.

Keywords: Alzheimer`s disease; dementia; gender differences; mild cognitive impairment; psychosocial interventions.