Early childhood exposure to a farm environment protects against atopic diseases into middle age

The findings are significant as previous research on the impact of rural environments on the development of atopic diseases has predominantly focused on childhood and young adulthood.

The study found that early childhood spent in a rural setting, particularly on a farm, significantly reduced the prevalence of conditions such as allergic rhinitis, allergic conjunctivitis, atopic multimorbidity, and polysensitisation at the age of 46. Among those who had lived in rural areas, the risk of sensitisation was nearly halved.

Haarala’s dissertation is based on data from over 5,000 individuals belonging to the Northern Finland Birth Cohort 1966. Participants completed surveys and underwent health examinations at the ages of 31 and 46. They were also tested for atopic sensitisation using skin prick tests for four allergens: birch, timothy grass, cat, and house dust mite.

Among the 46-year-olds studied, 7% had atopic dermatitis, nearly one-third had allergic rhinitis and conjunctivitis, and 9% had asthma. Additionally, around one-quarter of the participants had two or more atopic diseases. Of those with atopic dermatitis at age 46, three out of four also had another atopic condition, a factor that should be considered in the treatment of atopic dermatitis in adults.

The findings support the prevailing view that early childhood exposure to the diverse microbial environment of rural areas may protect against the development of atopic diseases. According to the study, this protective effect appears to extend at least into middle age. "Based on the findings, increasing children’s exposure to nature can be recommended as part of the prevention of atopic diseases," Haarala concludes.

Anna Haarala, Licentiate of Medicine, will defend her dissertation on 22 November.