PONE-D-20-11819

Traumatic Brain Injuries and Problem Gambling: Evidence from a population-based study of secondary students in Ontario, Canada.

PLOS ONE

Dear Dr. Turner,

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PLOS ONE

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4.Thank you for stating the following in the Competing Interests section:

[Turner has received funding from the Ontario Ministry of Health and Long Term Care (OMHLTC), Gambling Research Exchance (GREO) and from Ontario Lottery and Gaming (OLG). In all cases the contract included guarantees of independence and intellectual property rights for the researcher. Turner has also acted as a consultant on gambling problems for various government and legal entities.

The rest of the authors report no conflicts of interest, however the following authors  reported funding from various sources.

Jing Shi has received funding from GREO

Michael Cusimano reports funding from CIHR, CIMVHR, IBM, Mitacs.

Chrisinte Wilkensons reports funding from CIHR, OMHLTC, Higher Education Quality Council of Ontario, Workplace Safety and Insurance Board, Alcohol Countermeasures Systems Corp., and the CAMH Foundation (Caskey-Francis Family Award).

Robert Mann has received funding from CIHR, OMHLTC, and Ontario Ministry of Transportation,].

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Reviewers' comments:

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Comments to the Author

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Reviewer #1: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

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Reviewer #1: Yes

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Reviewer #1: No

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5. Review Comments to the Author

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Reviewer #1: The authors conducted an interesting research aimed at evaluating the relation between traumatic brain injury history and gambling severity in adolescents. Below, find some major and minor points that need to be addressed in order to improve the manuscript. After these changes, it will be possible to judge whether the research is suitable for publication.

Major revisions

In the first lines of the Introduction, the authors report the prevalence rates of gambling in adults and adolescents. About that, I suggest some revisions. First, the articles cited to report the prevalence rates are too old and should be updated (for example, Korn et al., 1999; Gupta et al., 1998; Turner et al., 2008, 2008, 2011). Second, in the line 71-77, the authors report adolescent gambling, then adult gambling, and then adolescent gambling again. I would suggest two options: 1) talk about adult and then adolescent gambling; 2) focus the introduction on adolescent gambling exclusively.

In the Introduction, line 86-89, the authors report studies that linked substance abuse, anxiety, and depression to problem gambling, but in adults and not in adolescents. I think the authors should mention the literature on adolescent gambling, given that their study is about adolescent gambling.

In the Introduction, line 96, the statement “Given the relationships of TBI with alcohol consumption and other substance use and mental health problems, it seems plausible that adolescent TBI may also be related to problem gambling.” Lacks of reference.

The rationale of the study is poor. There are no information of the process by which brain injury causes impulsive behaviors. There are little data about adolescent gambling. I think that the Introduction is not very persuasive and need to be improved.

It is not enough to refer the reader to other articles to know the procedure of the study (“Further information on the OSDUHS, including the sampling procedures and weighting of data, is available in references”). I believe it is necessary to report the procedure.

The first question about suicide attempt “did you ever seriously consider attempting suicide” is a little tricky. It is well known that suicide thoughts are common among people, especially in adolescents but that a thought not always is followed by an action. I know what you intend with “seriously” but I have doubts about the way in which adolescents could have interpreted this question, so I would recommend to use only the second question.

Discussion. The authors state “While there may be several possible explanations for this association, including underlying biological causes and shared personality factors (35, 54-56) recognition of this relationship has important implications for prevention and treatment.” What implications do they intend? It is necessary to specify.

Discussion, line 247. “We also observed that adolescent problem gambling was significantly associated with 248 increased suicidality, which is consistent with previous studies (11, 57, 58).”

The studies you cited are on adults or adolescents?

Discussion, line 248. “Similarly consistent with previous research, adolescent problem gambling was also significantly associated with hazardous or harmful drinking (4, 59, 60)”. The studies cited are too old if you consider that the association between alcohol use and gambling in adolescents has been highly investigated (see for example “Decision-Making, Cognitive Distortions and Alcohol Use in Adolescent Problem and Non-problem Gamblers: An Experimental Study”, “The Associations Between Maladaptive Personality Traits, Craving, Alcohol Use, and Adolescent Problem Gambling: An Italian Survey Study”, “Adolescent alcohol-drinking frequency and problem-gambling severity: Adolescent perceptions regarding problem-gambling prevention and parental/adult behaviors and attitudes”, or “A review of gambling disorder and substance use

disorders”).

The discussion is too poor and need to be enriched. For example, with clinical implications. Moreover, it is not clear to me what novelty results this study provides to the literature.

In general the references are too old and should be updated, especially the literature about adolescent gambling.

Minor revisions

The paper needs a more careful reading by the authors, as I found some typo, such as:

- In the Introduction, line 75, it should be “affects” and not “affect”.

- Introduction, line 105, “Similarly, recent a case-control study by Bhatti et al”.

- Introduction, line 109, “no studies have yet”.

- Methods, line 129. The authors say “The total sample size was 9,198 secondary school students 129 (52.0%)”. 52% of what?

- Measures, line 151. The “Diagnostic and Statistical Manual of Mental Disorders, 5th edition (45)” has another font and colour as compared with the paper.

- Measure, line 156. Given that it is also mentioned later, “which was developed by the World Health Organization (47)” should be removed. In the same way, the construct measured by the AUDIT and its number of items are reported twice.

References should be checked. For example, Derevensky J, Gupta R. Adolescents with gambling problems: A synopsis of our current 459 knowledge. Journal of Gambling Issues. 2004;10 lacks of number of pages.

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Reviewer #1: No

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Traumatic Brain Injuries and Problem Gambling in Youth: Evidence from a population-based study of secondary students in Ontario, Canada.

PONE-D-20-11819R1

Dear Dr. Turner,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Simone Rodda

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Thank you to the authors for responding to the extensive comments.