The fact that PTSD in men older than 72 years was associated with increased risk of developing PD later in life in our study may indicate that PTSD in older patients may actually be a prodromal symptom of PD, especially in the light of the fact that PARK2, a PD gene involved in dopamine regulation, is associated with PTSD in men, along with other novel genes and noncoding RNAs.36 Here, PRKN is linked to Parkinson disease.