Fig. 2

The results of the forward MR analysis. A The anatomical locations of the WM IDPs showing significant causal associations with migraine in the forward MR analysis. B The forest plot shows the results of causal estimates. Each box represents the effect (i.e., OR change) per 1 SD change in the respective IDP on migraine, and the error bars represent 95% CI. Arrows indicate that 95% CI exceeds the x axis. Significant causal correlation is defined as p value < 3.29 × 10^− 4 (Bonferroni correction) and marked by red chroma. The IVW (if the number of IVs > 1) -derived or Wald ratio (if the number of IVs = 1) -derived results were regarded as main results. Abbreviations: CI, confidence interval; IDP, imaging-derived phenotypes; IVs, instrumental variables; IVW, inverse variance-weighted; MR, Mendelian randomization; OR, odds ratio