2D:4D ratio, alexithymia, impulsivity, aggression, and ADHD in men with opioid and methamphetamine use disorders: A comparative analysis with healthy controls

Substance use disorder is an important mental health problem with increasing frequency. This study aims to investigate the 2D:4D ratio, Dr-I values (right-left differences), alexithymia, aggression, impulsivity, and attention deficit hyperactivity disorder (ADHD) symptoms in male patients with methamphetamine use disorder (MUD), opioid use disorder (OUD), and healthy controls. The study included a total of 57 male patients diagnosed with OUD, 42 male patients diagnosed with MUD, and 72 healthy male controls. The study indicated that the OUD and MUD patients were significantly different from the healthy controls in terms of the 2D:4D ratio, alexithymia, impulsivity, aggression, and ADHD. Compared to healthy controls, 2D:4D ratios, and Dr-I values were lower in OUD and MUD patients. OUD and MUD patients had higher scores of alexithymia, impulsivity, aggression, and ADHD compared to healthy controls. There were statistically significant negative correlations between the right-hand 2D:4D ratios and the ADHD, impulsivity, alexithymia and aggression scores and a significant negative correlation between Dr-I scores and the impulsivity scores of MUD and OUD patients. These findings contribute to the existing literature examining the complex relationship between prenatal testosterone exposure, substance use disorders and related psychological traits.