A Scoping Review of Rodent Studies Investigating the Epigenetic Mechanisms in the Brain Underlying the Effects of Diet on Depressive-like Behaviour
Bibliographic record
Abstract
A healthy diet has been highly associated with a decreased risk for mental health problems such as major depression. Evidence from human studies shows that diet can influence mood but there is a poor understanding of the molecular mechanisms behind these effects, especially the role of epigenetic alterations in the brain. Our objective was to use the Preferred Reporting Items for Systematic Reviews and Meta-Analysis extension for Scoping Reviews (PRISMA-ScR) format to gather all recent studies using animal models that investigate direct or indirect (on the offspring) effects of diet on depressive symptoms, including studies that assess epigenetic mechanisms in the brain. In this format, two authors conducted independent database searches of PubMed, Web of Science, and Academic search premier using one search block "diet epigenetics depression" to find papers published between 2000 and 2022. Relevant studies were selected using pre-defined inclusion/exclusion criteria that were performed independently by the two authors before a subset of studies were selected for qualitative analysis. A total of 11 studies met the inclusion criteria for this systematic scoping review. We found that the literature focuses primarily on the effects of individual nutrients, instead of a specific diet, on despair-like behaviour and anxiety. Studies are heterogenous with the techniques used to asses epigenetic changes in the brain and therefore making it hard to reach common mechanistic explanations. However, all studies report diet-induced changes in the epigenome mainly by the action of DNA methylation, histone acetylation and microRNAs that are parallelel with changes in behaviour. Moreover studies show that inadequate maternal diets can make the offspring more susceptible to develop anxiety and depressive-like behaviour later in life, which is paralleled with changes in the epigenome. Overall, this systematic review shows that there is some literature suggesting a role of brain epigenetics on the diet-induced protective or detrimental effects, specifically on anxiety and depressive-like behaviour. However, studies are limited, lacking the study of some types of diets, behavioural tasks or epigenetic mechanisms. Nevertherless, it shows the importance of genome-environment interactions, bringing new insights towards mechanisms that could be involved in the pathophysiology of mood disorders as well as putative therapeutic targets.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.020 | 0.076 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.009 | 0.011 |
| Bibliometrics | 0.022 | 0.021 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.003 | 0.003 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.009 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".