There may indeed be a seasonality to psoriasis—if trends in online searches about the disease are an indication.
Researchers analyzed relative search volume for psoriasis and related terms in Google Trends from January 2004 to December 2018. They found that searches peaked in late winter/early spring and dipped in late summer/early autumn in each hemisphere.
The analysis also showed a steady decline in searches for psoriasis from 2004 to 2010 that reversed from 2011 to 2018. The top 11 rising topics were calcipotriol/betamethasone dipropionate, ustekinumab, apremilast, shampoo, eczema, guttate psoriasis, seborrhoeic dermatitis, dermatitis, psoriatic arthritis, atopic dermatitis and arthritis.
Countries included in the research include Australia, New Zealand, USA, Canada, UK, and Ireland.
— Postgrad Med J. 2019Sept., e-Pub