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:

• dementia
• Alzheimer`s disease
• mild cognitive impairment
• psychosocial interventions
• gender differences

Acknowledgements

We thank Anima Pieper and Ylva Köhncke for their support in literature research, and Dr Sabine Oertelt-Prigione, Institute of Gender in Medicine, Center for Cardiovascular Research, Charité Berlin, for valuable advice.

Notes

1 In this study, data from 21 European and North American studies were pooled. The disease prevalence in women was greater by a factor of 2.07 compared to men, corresponding to a gender distribution of 67% women and 33% men in a gender stratified study sample. Higher rates of women were reported in the EURODEM study, resulting in a male:female ratio of 1:2.26 (Lobo et al., 2000). For our review, we used the more conservative estimate by Hy and Keller (2000).

Additional information

Funding

The study was supported by the Humboldt University Fund for Gender Equality 2011.