The influence of intergenerational trauma on epigenetics and obesity in Indigenous populations - a scoping review

Figures & data

Figure 1. Selection process in PRISMA flow diagram.

Table 1. Characteristics of reviewed studies.

Authors (Year)	Study Site	Years(s) of data collection	Sample Size and Population	Age Range of Sample	Study Design
1- [20]	Ukraine	July-November 2010	45 participants (15 families: survivors of the Holodomor Genocide and their adult children and grandchildren)	86.4, 57.6, 3.3 years (means of each generation)	Qualitative
2- [2]	University of Lethridge, Alberta, Canada	n/a	90 participants (self-identified as First Nations, Inuit, or Métis)	Over 18 (mean: 28 years)	Cross-sectional & Qualitative
3- [21]	Australia	n/a	26 participants (ME [Middle Eastern Mothers])	35–59 years	Qualitative
4- [24]	Mexica	n/a	19 participants (9 Mexican geneticists and 10 medical staff)	n/a	Qualitative
5- [22]	UK	n/a	209 grandmother-mother pairs and 355 grandchildren from Isle of Wight birth cohort	1–26 years	Cohort
6- [23]	Six Nations Reserve and Pigeon Lakes Reserve, Canada	2015–2017	Phase 1 = 37 participants (parents, elders, academic researchers, health service representatives); Phase 2 = 23 participants (community members providing health care services, parents, and community members with Indigenous knowledge)	n/a	Qualitative & 2-phase

Table 2. Themes of reviewed studies.

Authors (Year)	Theme	Obesity	Epigenetics	Trauma	Indigeneity	Intergenerational vs Transgenerational
1- [20]	Behaviorally, Culturally	No	Yes	Yes	No	Both
2- [2]	Behaviorally, Biologically	Yes	Yes	Yes	Yes	Both
3- [21]	Behaviorally, Culturally	Yes	No	Yes	No	Intergenerational
4- [24]	Biologically, Culturally	Yes	Yes	No	Yes	Transgenerational
5- [22]	Biologically	Yes	Yes	No	No	Both
6- [23]	Behaviorally, Culturally	Yes	No	Yes	Yes	Intergenerational

Table 3. Results of reviewed studies.

Authors (Year)	Impact of Intergenerational Trauma	Linkage between Epigenetics and Obesity	Discussion of Indigeneity	Maternal or Paternal	Future Research
1- [20]	Trauma impacted emotions and inner states and influenced trauma-based coping strategies	Social experiences may affect genetic expression: epigenetics may provide context on the generational transmission of trauma and collective trauma. The impacts found sometimes led to overweight individuals	n/a	Article is not explicit on maternal influence, but only mentions the habits and influences of mothers	Multi-level frameworks of healing
2- [2]	Traumatic stress may be passed down via epigenetic and behavioural pathways. Parental experience in a residential school influenced allostatic load on their offspring	Parental experience in residential schools increased allostatic load on offspring, regardless of if they were raised by these parents	Health and social disparities in Indigenous Canadians are rooted in colonialism, racism, and oppression. Residential schools imparted emotional, physical, and sexual abuse as well as neglect. Repeated or chronic stress is demonstrated by allostasis built on the psychosocial model	Maternal line	Additional research and better understandings of neurobiological and genetic components of trauma stemming from residential schools, and thus health inequalities
3- [21]	Diaspora sometimes resulted in diet acculturation and intergenerational trauma, creating a culture of feeding	n/a	n/a	Mothers and maternal line	Culturally relevant programs, parent workshops, and government initiatives
4- [24]	n/a	Obesity can have epigenetic influences: diet and lifestyle of mothers can shape health and disease outcomes for offspring and future generations; obesity is one example of this	Studies show high levels of genetic markers that are Indigenous American in origin in the mitochondrial DNA of Latin American mestizos, while their Y-chromosome DNA contains high levels of genetic markers that are European in origin. As Indigenous genetic ancestry is linked to obesity, discourse arise centred on racialized and gendered concepts of heredity	The maternal body. Epigenetics can reinforce racialized differences and health inequities, while serving as technologies to reclaim history, culture, and knowledge	Evaluate how Indigenous and maternal bodies are being placed at the centre of health risks linked to obesity
5- [22]	n/a	There is a transgenerational role of grand-maternal BMI on increased grandchild’s BW	n/a	Maternal line	Future studies on the paternal line
6- [23]	Intergenerational trauma has a large influence on community and individual health, and obesity	n/a	Indigenous Canadians have a disproportionate burden of obesity and obesity-related diseases, which could be related to intergenerational trauma exposures. Indigenous ways of life such as traditional knowledge and teachings are synonymous with participation in physical activity and healthy food choices. Cultural continuity is protective in these concerns	Mothers participated in study	Cultural connection and cultural continuity; interventions must be Indigenous-led and multilevel

Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) Checklist.

SECTION	ITEM	PRISMA-ScR CHECKLIST ITEM	REPORTED ON PAGE #
TITLE
Title	1	Identify the report as a scoping review.	1
ABSTRACT
Structured summary	2	Provide a structured summary that includes (as applicable): background, objectives, eligibility criteria, sources of evidence, charting methods, results, and conclusions that relate to the review questions and objectives.	1
INTRODUCTION
Rationale	3	Describe the rationale for the review in the context of what is already known. Explain why the review questions/objectives lend themselves to a scoping review approach.	2
Objectives	4	Provide an explicit statement of the questions and objectives being addressed with reference to their key elements (e.g., population or participants, concepts, and context) or other relevant key elements used to conceptualize the review questions and/or objectives.	5
METHODS
Protocol and registration	5	Indicate whether a review protocol exists; state if and where it can be accessed (e.g., a Web address); and if available, provide registration information, including the registration number.	5
Eligibility criteria	6	Specify characteristics of the sources of evidence used as eligibility criteria (e.g., years considered, language, and publication status), and provide a rationale.	6
Information sources*	7	Describe all information sources in the search (e.g., databases with dates of coverage and contact with authors to identify additional sources), as well as the date the most recent search was executed.	6
Search	8	Present the full electronic search strategy for at least 1 database, including any limits used, such that it could be repeated.	6
Selection of sources of evidence†	9	State the process for selecting sources of evidence (i.e., screening and eligibility) included in the scoping review.	7
Data charting process‡	10	Describe the methods of charting data from the included sources of evidence (e.g., calibrated forms or forms that have been tested by the team before their use, and whether data charting was done independently or in duplicate) and any processes for obtaining and confirming data from investigators.	8–9
Data items	11	List and define all variables for which data were sought and any assumptions and simplifications made.	8–9
Critical appraisal of individual sources of evidence§	12	If done, provide a rationale for conducting a critical appraisal of included sources of evidence; describe the methods used and how this information was used in any data synthesis (if appropriate).	N/A
Synthesis of results	13	Describe the methods of handling and summarizing the data that were charted.	8
RESULTS
Selection of sources of evidence	14	Give numbers of sources of evidence screened, assessed for eligibility, and included in the review, with reasons for exclusions at each stage, ideally using a flow diagram.	Supplementary materials, Fig. 1
Characteristics of sources of evidence	15	For each source of evidence, present characteristics for which data were charted and provide the citations.	9–11
Critical appraisal within sources of evidence	16	If done, present data on critical appraisal of included sources of evidence (see item 12).	N/A
Results of individual sources of evidence	17	For each included source of evidence, present the relevant data that were charted that relate to the review questions and objectives.	11–14
Synthesis of results	18	Summarize and/or present the charting results as they relate to the review questions and objectives.	Supplementary materials, Tables 1, 2, & 3
DISCUSSION
Summary of evidence	19	Summarize the main results (including an overview of concepts, themes, and types of evidence available), link to the review questions and objectives, and consider the relevance to key groups.	14
Limitations	20	Discuss the limitations of the scoping review process.	19
Conclusions	21	Provide a general interpretation of the results with respect to the review questions and objectives, as well as potential implications and/or next steps.	19–20
FUNDING
Funding	22	Describe sources of funding for the included sources of evidence, as well as sources of funding for the scoping review. Describe the role of the funders of the scoping review.	20

JBI = Joanna Briggs Institute; PRISMA-ScR = Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews.

*Where sources of evidence (see second footnote) are compiled from, such as bibliographic databases, social media platforms, and Web sites.

†A more inclusive/heterogeneous term used to account for the different types of evidence or data sources (e.g., quantitative and/or qualitative research, expert opinion, and policy documents) that may be eligible in a scoping review as opposed to only studies. This is not to be confused with information sources (see first footnote).

‡The frameworks by Arksey and O’Malley (6) and Levac and colleagues (7) and the JBI guidance (4, 5) refer to the process of data extraction in a scoping review as data charting.

§The process of systematically examining research evidence to assess its validity, results, and relevance before using it to inform a decision. This term is used for items 12 and 19 instead of ‘risk of bias’ (which is more applicable to systematic reviews of interventions) to include and acknowledge the various sources of evidence that may be used in a scoping review (e.g., quantitative and/or qualitative research, expert opinion, and policy document).

Bezo B, Maggi S. Living in “survival mode:” intergenerational transmission of trauma from the Holodomor genocide of 1932–1933 in Ukraine. Soc Sci Med. 2015;134:87–94. doi: 10.1016/j.socscimed.2015.04.009

 PubMed Web of Science ®Google Scholar

Chief Moon-Riley K (2017). The biological impacts of residential schooling on the development of intergenerational trauma among Indigenous people [ Master’s Thesis, University of Lethbridge]. OPUS. Retrieved from https://opus.uleth.ca/bitstream/handle/10133/4904/CHIEF_MOON_RILEY_KATHRINA_MSC_2017.pdf?sequence=9&isAllowed=y

 Google Scholar

Hayba N, Shi Y, Allman-Farinelli M. Enabling better nutrition for adolescents from middle Eastern backgrounds: semi-structured interviews with parents. Nutrients. 2021;13(11):3918. doi: 10.3390/nu13113918

 PubMed Web of Science ®Google Scholar

Saldaña-Tejeda A. Mitochondrial mothers of a fat nation: race, gender and epigenetics in obesity research on Mexican mestizos. BioSocieties. 2017;13(2):434–452. doi: 10.1057/s41292-017-0078-8

 Web of Science ®Google Scholar

Shen Y, Zhang H, Jiang Y, et al. Maternal birth weight and BMI mediate the transgenerational effect of grandmaternal BMI on grandchild’s birth weight. Obesity. 2020;28(3):647–654. doi: 10.1002/oby.22680

 PubMed Web of Science ®Google Scholar

Wahi G, Wilson J, Oster R, et al. Strategies for promoting healthy nutrition and physical activity among young children: priorities of two indigenous communities in Canada. Curr Dev Nutr. 2019;4(1):nzz137. doi: 10.1093/cdn/nzz137

 PubMed Web of Science ®Google Scholar

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article [and/or] its supplementary materials.