After screening, we identified that a genetic predisposition to antihypertensives (C02), thyroid preparations (H03A), and immunosuppressants (L04) was causally associated with a decreased risk of AD, a predisposition to thyroid preparations (H03A), immunosuppressants (L04), and glucocorticoids (R03BA) was causally associated with a lower risk of PD, and a predisposition to antithrombotic agents (B01A), HMG CoA reductase inhibitors (C10AA), and salicylic acid and derivatives (N02BA) was causally associated with a higher risk of ALS (Figure 2 and Figure 3). Here, HMGCR is linked to Parkinson disease.