Distribution and heritability of diurnal preference (chronotype) in a rural Brazilian family-based cohort, the Baependi study

Author(s)

von Schantz, Malcolm ^{[1, 2]} ; Taporoski, Tamara P. ^{[2, 3]} ; Horimoto, Andrea R. V. R. ^[2] ; Duarte, Nubia E. ^[2] ; Vallada, Homero ^[3] ; Krieger, Jose E. ^[2] ; Pedrazzoli, Mario ^[4] ; Negrao, Andre B. ^{[2, 3]} ; Pereira, Alexandre C. ^[2]

Affiliation

^[1] Univ Surrey, Fac Hlth & Med Sci, Guildford GU2 5XH, Surrey - England

^[2] Univ Sao Paulo, Lab Genet & Mol Cardiol, Heart Inst Incor, Sch Med, Sao Paulo, SP - Brazil

^[3] Univ Sao Paulo, Sch Med, Dept & Inst Psychiat LIM 23, Sao Paulo, SP - Brazil

^[4] Univ Sao Paulo, Sch Arts Sci & Humanities, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: SCIENTIFIC REPORTS; v. 5, MAR 18 2015.
• Web of Science Citations: 30

Abstract

Diurnal preference (chronotype) is a useful instrument for studying circadian biology in humans. It harbours trait-like dimensions relating to circadian period and sleep homeostasis, but also has ontogenetic components (morningness increases with age). We used the Morningness-Eveningness questionnaire (MEQ) in the Baependi study, a family-based cohort study based in a small town in Minas Gerais, Brazil. The population is highly admixed and has a cohesive and conservative lifestyle. 825 individuals (497 female) aged 18-89 years (average +/- SD = 46.4 +/- 16.3) and belonging to 112 different families participated in this study. The average MEQ score was 63.5 +/- 11.2 with a significant (P < 0.0001) linear increase with age. Morningness was significantly (P, 0.0001) higher in the rural (70.2 +/- 9.8) than in the municipal zone (62.6 +/- 11.1), and was also significantly (P = 0.025) higher in male (64.6 +/- 10.9) than in female (62.8 +/- 11.2) participants. Thus, in spite of universal access to electricity, the Baependi population was strongly shifted towards morningness, particularly in the rural zone. Heritability of MEQ score was 0.48 when adjusted for sex and age, or 0.38 when adjusted for sex, age, and residential zone. The reported MEQ score heritability is more akin to those of previous twin studies than previous family studies. (AU)

• FAPESP's process: 13/17368-0 - Cardiovascular genomics: mechanisms & novel therapeutics - CVGen mech2ther
• Grantee: José Eduardo Krieger
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 11/05804-5 - Phenotypic characterization of circadian rhythms in different genotype individuals for clock gene polymorphisms in different regions in Brazil: an emphasis on the effect of the gene PER3 and latitude
• Grantee: Mario Pedrazzoli Neto
• Support Opportunities: Regular Research Grants