For decades, women have been neglected in cardiovascular research. With growing evidence
to support a connection between the heart and the brain, we systematically reviewed
the status of women included in experimental research assessing the impact of coronary
heart disease (CHD) on neuropsychological functions.
METHODS AND RESULTS
We conducted a systematic review and used the PRISMA guidelines to report our findings.
We screened a total of 26,843 references, of which 418 remained for full-text screening
and only 13 were included in the final analysis. Throughout the screening process,
we excluded studies which did not include women or participants with CHD or its subtypes
(e.g., myocardial infarction, angina pectoris), or did not perform a neuropsychological
– or variant - assessment. During the full-text screening, we excluded studies that
did not perform separate statistical analyses for sexes or for conditions (e.g., combining
CHD and heart failure participants). Close to half of the studies (161 studies; 46.60%)
were excluded during the full-text screening phase because there was no separate analysis
for women, exhibiting the underwhelming attention given to sex differences in CHD
research. Of the 13 studies kept, 11 had samples composed of 36% or fewer women, and
all studies, except one, failed to report the power and effect size of their sample.
Furthermore, only one study considered menstrual cycle/menopause status, although
it is known to influence performance on cognitive testing and CHD progression. Demographic
variables that are commonly acknowledged to be cardiovascular risk factors (e.g. cholesterol,
hypertension, smoking, etc.) were often measured but rarely compared between sexes,
providing an incomplete picture of the underlying factors which affect the women included
in these studies.
Our systematic review shows that women are still strikingly underrepresented in CHD
research. Based on our findings, we propose the following guidelines: 1) the number
of women included in CHD research should be similar to the CHD prevalence in the general
population; 2) researchers should calculate the power and effect size of their samples;
3) menstrual cycle or menopausal status should be taken into account; and 4) all demographic
variables should be reported separately for men and women. These guidelines aim to
improve cardiovascular research in women, so that future research trials can better
Natural Sciences and Engineering Research Council (NSERC)