No Evidence for Cross-Sectional or Longitudinal Associations between Cognitive Flexibility Performances and Nutritional Status in a Cohort of Inpatients with Anorexia Nervosa

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Nutrients – Peer Review for nutrients-3046752

This paper investigated the relationship between cognitive flexibility and nutritional status in people with anorexia nervosa (AN). The study was informed by a theoretical model for AN (i.e., the Cognitive-Interpersonal Model of AN) and supported by previous research. The introduction is well written and provides a sound rationale for the study. A further strength is the large sample size and comprehensive evaluation of nutritional status. The authors found that after controlling for age and psychomotor speed, cognitive flexibility was not associated with nutritional status at intake nor at discharge. However, cognitive flexibility performance improved longitudinally.

Please see below for specific comments on areas of the manuscript which require revisions and improvement.

 

Methods:

1.       Insufficient information is provided for the self-report questionnaires. Please include the number of items on each scale, information about any subscales, the reliability of the scales in the current study (i.e. Cronbach’s alpha) and how the scores should be interpreted.

2.       As cognitive flexibility is the primary outcome, more information is needed about the flexibility task. For example, were participants informed if their responses were correct or incorrect? In what environment did the participants complete the task (i.e. were there any potential distractions)?

3.       How was illness duration calculated? Was it calculated from time of diagnosis? Or from time of significant symptom onset?

4.       The design of this study is unclear. It is not evident when or how assessments were administered.

5.       Regarding line 165-166 – can the authors please provide more information about the Bonferroni correction.

6.       Was an a priori power analysis completed? If no, could a post-hoc power analysis please be reported.

Results:

7.       Details regarding missing data should be included in the statistical analysis report section rather than the results.

8.       Table 1 – the term ‘evolution’ is vague. Can the authors please be more specific here.

9.       Lines 265-269 – the first sentence in this section states that there were no significant associations between the variables, however, the following sentence contradicts this statement and remarks that the associations were “null or negligible”. Please provide some clarification here; were some of the associations significant? Or were all associations null?

Discussion:

10.   Line 317 – The phrase “patients suffering from AN” is inappropriate and stigmatising. Please amend to “patients diagnosed with AN”

11.   In the discussion (line 322) the mention of autism spectrum disorder seems somewhat off topic. This section should be amended to improve the flow and focus of the discussion.

12.   In my opinion, the Discussion would be enhanced by further discussion of cognitive flexibility as a state or trait construct (particularly given then findings related to anxiety and depression).

13.   A key finding of this paper is that cognitive flexibility improved over time, yet cognitive flexibility performance was not associated with nutritional status. This finding challenges suggestions in the literature that poor cognitive flexibility in AN may be a consequence of starvation and low weight. The Discussion would be strengthened if these longitudinal findings were discussed in further detail. Do the authors have any hypotheses for why cognitive flexibility improved? From my reading of this paper it appears that the authors do not consider this result to be the consequence of a practice effect.

14.   Given that only females were included in the current study, it should be noted in the limitations section that the findings may not generalise to other sexes/genders.

General:

 

15.   In the Introduction and Discussion, the authors refer to the ‘stages’ of AN and suggest that they are examining cognitive flexibility at different illness stages. However, in the Methods and Results sections, it is unclear how AN illness stage is being identified/evaluated and which analyses are related to AN illness stage. 

Author Response

Please see attachement

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This is a quality study, with a large and very specific sample, which is of great value. However, I consider it important to make the following recommendations: 

- The connection between the Cognitive-Interpersonal theory of Anorexia Nervosa, cognitive flexibility and BMI is not well understood in the abstract. It should be clearly explained why the results are in line with this theory.

- Much of the referenced literature is very old. A review of the current literature of the last five years is desirable and this section, as well as the Discussion linked to it, should be expanded.

- Section 2.1 and 3.1 should be merged into Method (2.1). The representation of the sample should also be complemented by graphs that visually show the distribution of the sample on the most relevant attributional variables.

- All instruments used should be cited with their authors, original scales and psychometric properties of reliability and validity. Their use should also be justified over other instruments.

- The Conclusions section should not contain citations. If it is essential to include these citations in the text, it is because these paragraphs should belong to the Discussion. Please review this.

Author Response

Please see attachment

Author Response File: Author Response.pdf