The Impact of Latitude on the Prevalence of Seasonal Depression
Bibliographic record
Abstract
Background: This study sought to determine whether the prevalence of the seasonal subtype of major depression (SAD) in the community varied as a function of latitude. Methods: Random telephone numbers were generated across 8 degrees of latitude (41.5 °N to 49.5°N) for the province of Ontario. Eight strata of 1 degree each were sampled equally throughout a 12-month period. Using a validated and structured diagnostic interview, we interviewed by telephone respondents over 20 years of age who had lived in the region for 3 years or more. We evaluated patterns of symptom change across seasons to establish a diagnosis of SAD according to DSM-IV criteria. Results: Of the 2078 households that were assessed for eligibility, 1605 (77%) completed the interview. The crude prevalence of lifetime SAD was 2.6% (95% CI, 1.9 to 3.5). There was no impact of latitude on prevalence of either major depression or the seasonal subtype across the 8 strata, although the global measure of the severity of seasonal change in mood was significantly negatively correlated with latitude. Conclusions: SAD is a common subtype of major depression in Ontario, but there is no evidence to support an increase in prevalence with increasing latitude. Contexte: Cette étude visait à déterminer si la prévalence du caractère saisonnier de la dépression majeure (DMS) dans la communauté variait selon la latitude. Méthodes: Des numéros de téléphone aléatoires ont été fournis sur 8 degrés de latitude (de 41,5°N. à 49,5°N.) dans la province de l'Ontario. Huit bandes de 1 degré chacune ont été échantillonnées également sur une période de 12 mois. À l'aide d'une entrevue diagnostique validée et structurée, nous avons interviewé par téléphone des répondants âgés de plus de 20 ans qui habitaient la région depuis 3 ans ou plus. Nous avons évalué les changements des modèles de symptômes selon les saisons pour établir un diagnostic de DMS selon les critères du DSM-IV. Résultats: Sur les 2 078 ménages admissibles, 1 605 (77 %) ont terminé l'entrevue. La prévalence brute de la DMS à vie était de 2,6 % (95 % IC, 1,9 à 3,5). La latitude n'influait pas sur la prévalence de la dépression majeure ou du caractère saisonnier dans les 8 bandes, bien que la mesure globale de la sévérité du changement saisonnier de l'humeur ait indiqué une corrélation négative significative à la latitude. Conclusions: La dépression majeure saisonnière est un sous-type répandu de la dépression majeure en Ontario, mais aucune preuve ne soutient une augmentation de la prévalence parallèle à l'accroissement de la latitude.
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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 | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".