Bampton et al. provide an accurate and concise review of the literature on the underpinnings and associations of cognitive and behavioural change in ALS. Please see my comments/suggestions numbered below:

1. Year of Gallassi et al. reference missing, p4.

2. I think there might be a word missing in the senstence: as self reported or a close friend ... p6

3. Is the meta analysis by Yang robust enough to make a firm statement of association? Are we convinced that enough studies have adequately controlled for dysarthria from their performance metrics.

4. Whilst commenting on the welcome development of the ECAS, it might be useful to mention that it has been translated widely, and that alternative versions facilitate longitudinal assessment whilst reducing practise effects. However, it must also be acknowledged that very few languages have all 3 versions translated, and that there's variability in how the ECAS is used to screen for impairment.

5. The section on longitudinal studies is very strong. The big standout for me is Bersano 2020, which seems to show quite a lot of decline over a relatively short period of time, whilst most of the other studies did not. I wonder if there's a methodological reason for this? I know Bersano focused on categorisation and the proportion of patients who changed categories over time. Is this enough to account for the difference, or is it because they had a large sample size, a good battery and crucially low attrition?

6. When comparing longitudinal studies, I was also wondering how similar studies were in their sampling. Were patients recruited relatively close to diagnosis, or at any time, or was there a lot of variability in their inclusion criteria. It might be relevant to highlight which studies had control groups, and how that might influence how we interpret the weight of their findings. Again, this might help us understand why some studies are showing decline while others aren't.

I guess, the main thing I'm wondering, is to what extent can methodological differences explain the contrasting results, and is there 1 or 2 studies that we should consider more robust

1. One further point on longitudinal studies is whether the study did an analysis comparing those who dropped out, with those who didn't. This would help us understand if the more impaired participants are consistently dropping out of studies.

2. The section on pre-symptomatic carriers is also very strong. I would just add that in one of the studies you cite (at a later stage: Costello et al. 2023) they found that verbal fluency deficits can also be observed in non-c9 relatives of familial ALS cases, which might indicate fluency deficits are an endophenotype of ALS risk more broadly rather than a specifically C9 mediated. Just something to consider.

3. The Gregory paper is very interesting, and of course very important to this review. I was wondering if you came across any similar studies in FTD samples? This might give us clues as to how credible the 100% ECAS specificity is that Gregory found.

4. Missing a full stop on the final line of page 16, after "sequential manner".

5. On SOD1, I'm aware of a study by Ivar Winroth et al. that was just accepted for publication in the Journal of Clinical and Experimental Neuropsychology specifically on SOD1 cognitive correlates. Hopefully it will be available soon as it is particularly relevant to this section. Or perhaps you could contact the author for a copy.

6. Typo on page 20, last line of second paragraph, 'withn a' should be 'within an'.

7. Is there any literature on the association between cognitive and behavioural change and neurofilament levels? Perhaps it is not within the scope of your review, but it's something readers might be wondering.

8. Please note, track changes author comments are visible on figure 1.

9. Overall, I believe the authors give an excellent summary of the literature. In places I would appreciate a bit more critical interpretation, to help the reader understand why there might be contrasting findings, and which studies results are potentially more robust.