Title: Association between physical activity and cognitive function in post-menopausal women
with high parity: the chain-mediating effects of nutritional status and depression
Version: 2 Date: 27 Jun 2024
Reviewer's report:
This manuscript addresses a potentially interesting topic about the association between physical
activity and cognitive function in postmenopausal women and effect modification by parity. In
addition, the authors explore mediation by BMI, nutritional status and depression.
The version I am reading is apparently a revised manuscript, but I do not have any information
on what has already been addressed.
1. Given that the analysis is limited to post-menopausal women, this should be reflected in the
title.
2. Something is wrong at the end of line 11.
3. Mediation analysis is best interpreted in longitudinal data so there is more evidence of causal
associations.  Requires careful interpretation in this cross-sectional data.  Each of the ‘mediating’
variables could be a confounder as well and without any temporal sequence you cannot ever
determine what the direction of association is.
4. In abstract conclusion on line 21, how was high risk of cognitive decline defined?
5. Line 30 notes higher dementia prevalence in women relative to men, but is this for same age
of men and women which I important because women tend to live longer and sicker than men.
6. The physical activity data is not very detailed and is divided only into two groups, one below
standard and the other above a standard. How will this data be used to inform more precise
interventions with regard to amounts or types of PA that might be beneficial?
7. Line 121, were weight (mass) and height measured or self-reported?
8. Line 123 where MNA is introduced a ref to this tool should be provided. The following line
talks about there being 18items in the full form of the MNA but this just makes it unclear whether
there is another less full version of the MNA, and does not say which was used.
9. If BMI is part of the MNA it should not be included as a separate variable in the same model.
10. More explanation of the MNA score is required, how do you get a max score of 30 from
18 items?
11. Line 140, remove sex from the list of covariates as only females can be included in this study.
12. In the section on covariates should give more information on how smoking and alcohol data
were collected, what time period, and how these were categorised. It appears from the tables
that it was only yes/no which is not great for accounting for their possibly important role in
the associations being studied.  For example, lines 170-72, you don’t know whether there was
any difference between the parity groups in the amount of cigarettes or alcohol used, only the
proportion of participants who had any use.  Looking at Table 1 where great majority of women
did not use cigarettes or alcohol this might be OK but perhaps mention the very low use in the
text as a reason for not including further detail.
13. Some of the comorbidities could also be on the pathway between PA and cognitive function.
14. Line 150 should say medians (interquartile ranges [IQRs]) were presented for variables with
non-normal distribution.
15. Line 151 refers to comparison between two groups but what these two groups are has not
been made clear.
16. Line 168-9, rephrase the comment on PA and parity, maybe ‘…the low parity group were
more likely to be physically active.’
17. Although it looks as though the association between PA and cognitive function varies by
parity, was an interaction between PA and parity ever tested?
18. Correlation should not be used to describe associations unless they are the result of specific
correlation analysis eg bottom of page 11.
19. Line 220, ‘…indicating that higher parity is more vulnerable to cognitive decline’ should be
‘…women with higher parity were…’
20. Even if it were assumed that associations between PA and MNA or depression were casual,
and that MNA and depression were causally related to poor cognitive function, what does this
information mean in terms of what would be recommended for women? More PA is generally
beneficial and without major side effects so generally good to recommend.
21. Lack of comparison with a nulliparous group is noted as a limitation, why wasn’t this
included?
22. The final sentence of the conclusion identifies women with increased risk of cognitive
decline according to parity, MNA and depression but this is not the research question, and if PA
intervention was the answer it doesn’t make sense to include mediator variables which come
after PA in the causal chain, in the criteria for selecting women for PA due to increased risk.
23. Apparently two authors wrote the first draft of the manuscript, perhaps would make more
sense to say they ‘co-wrote’ the manuscript.
24. Some refs are missing page numbers.
25. Table 1 title needs to be more informative, where were the participants from, what years
were data collected.
26. Table 2, give numbers in each group and analysis.