Prevalence of visual snow syndrome in the UK.

BACKGROUND AND PURPOSE: Visual snow syndrome is a recently described condition of unknown prevalence. We investigated the prevalence in a representative population sample from the UK and tested the hypothesis that visual snow syndrome is associated with young age, headache, tinnitus and mood impairment. METHODS: Using a crowdsourcing platform, we recruited a representative sample of 1015 adult laypeople from the UK, matched for age, gender and ethnicity according to national census data. Participants were unprimed, i.e. were inquired about the 'frequency of certain medical conditions' but not 'visual snow syndrome'. RESULTS: A total of 38 of 1015 participants reported symptoms compatible with visual snow [3.7%; 95% confidence interval (CI), 2.7-5.2] and 22/1015 met criteria for visual snow syndrome (2.2%; 95% CI, 1.4-3.3). The female-to-male ratio for visual snow syndrome was 1.6:1. Subjects with visual snow syndrome were older (50.6 ± 14 years) than the population mean (44.8 ± 15 years), although this was not statistically different (P = 0.06). Of 22 participants with visual snow syndrome, 16 had mood symptoms (72.7%; P = 0.01), 12 had headache (54.5%; P = 0.06), including five with visual migraine aura (22.7%; P = 0.15) and 13 had tinnitus (59.1%; P < 0.001). No participant had diabetes or a cleft lip (control questions). Following a multivariable regression analysis to adjust for age and gender, only the association between visual snow syndrome and tinnitus remained significant (odds ratio, 3.93; 95% CI, 1.63-9.9; P = 0.003). CONCLUSIONS: The UK prevalence of visual snow syndrome is around 2%. We confirmed an association with tinnitus, but unprimed laypeople with visual snow syndrome are on average older than those seeking medical attention.