title: Early-life hygiene-related factors affect risk of central nervous system demyelination and asthma differentially.
abstract: The increasing prevalence of immune-related diseases, including multiple sclerosis, may be partly explained by reduced microbial burden during childhood. Within a multi-centre case-control study population, we examined: (i) the co-morbid immune diseases profile of adults with a first clinical diagnosis of central nervous system demyelination (FCD) and (ii) sibship structure in relation to an autoimmune (FCD) and an allergic (asthma) disease. FCD cases (n = 282) were aged 18-59 years; controls (n = 558) were matched on age, sex and region. Measures include: history of doctor-diagnosed asthma; sibling profile (number; dates of birth); and regular childcare attendance. FCD cases did not differ from controls with regard to personal or family history of allergy, but had a greater likelihood of chronic fatigue syndrome [odds ratio (OR) = 3·11; 95% confidence interval (CI) 1·11, 8·71]. Having any younger siblings showed reduced odds of FCD (OR = 0·68; 95% CI: 0·49, 0·95) but not asthma (OR = 1·47; 95% CI: 0·91, 2·38). In contrast, an increasing number of older siblings was associated with reduced risk of asthma (P trend = 0·04) but not FCD (P trend = 0·66). Allergies were not over-represented among people presenting with FCD. Sibship characteristics influence both FCD and asthma risk but the underlying mechanisms differ, possibly due to the timing of the putative 'sibling effect'.
authors.affiliation: National Centre for Epidemiology and Population Health, Australian National University, Canberra, Australia. annmaree.hughes@anu.edu.au
authors.forename: A-M
authors.initials: AM
authors.lastname: Hughes
authors.forename: R M
authors.initials: RM
authors.lastname: Lucas
authors.forename: A J
authors.initials: AJ
authors.lastname: McMichael
authors.forename: T
authors.initials: T
authors.lastname: Dwyer
authors.forename: M P
authors.initials: MP
authors.lastname: Pender
authors.forename: I
authors.initials: I
authors.lastname: van der Mei
authors.forename: B V
authors.initials: BV
authors.lastname: Taylor
authors.forename: P
authors.initials: P
authors.lastname: Valery
authors.forename: C
authors.initials: C
authors.lastname: Chapman
authors.forename: A
authors.initials: A
authors.lastname: Coulthard
authors.forename: K
authors.initials: K
authors.lastname: Dear
authors.forename: T J
authors.initials: TJ
authors.lastname: Kilpatrick
authors.forename: D
authors.initials: D
authors.lastname: Williams
authors.forename: A-L
authors.initials: AL
authors.lastname: Ponsonby
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000209:etiology* / Q000276:immunology / Q000382:microbiology; D015551:Autoimmunity; D016022:Case-Control Studies; D003711:Demyelinating Diseases / Q000209:etiology* / Q000276:immunology / Q000382:microbiology; D015673:Fatigue Syndrome, Chronic / Q000209:etiology / Q000276:immunology; D005260:Female; D006801:Humans; D006920:Hygiene; D061148:Hygiene Hypothesis; D006967:Hypersensitivity / Q000209:etiology / Q000276:immunology / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D035781:Siblings; D055815:Young Adult