Introduction:
TRPM8 is an immune system regulator with a peak activity at 8°C–10°C. Multiple sclerosis (MS) is a condition that is noted for an increasing prevalence with latitude. Prevalence rates have, however, been noted to drop in northern regions with averages yearly temperatures below 8°C

Aim:
To determine whether MS prevalence rates are associated with the peak of TRPM8 activity of 8°C–10°C both by average yearly temperature and by variation towards that temperature.

Material and methods:
Multivariate analysis was used to determine the significance of association between MS prevalence, average yearly temperature, and with variation towards a particular temperature. This method was repeated for eight independent regions, all regions combined, and all regions except Russia and Scandinavia.

Results and discussion:
Results showed an average yearly temperature for peak MS prevalence between 6.00°C and 10.80°C depending on region. The average temperature for peak effects of variation was between 7.80°C and 8.70°C depending on region, with the UK and Scandinavia non-significant. The average temperature of association with MS for all regions was 9.21° by temperature (P < 0.05) and by variation 8.67°C (P < 0.005). Without Russia and Scandinavia the average temperature was 10.55°C (P < 0.05) and variation was not significant.

Conclusions:
Removing northern regions from the model causes variation to become non-significant by removing areas where, on average, variation towards warmer temperatures increase MS rates instead of variation towards lower ones. This provides evidence that average yearly temperature and variation from that temperature are responsible for significant variations in MS prevalence rates worldwide.