The 2D:4D Marker and Different Forms of Internet Use Disorder

Area of Science:

• Neuroscience
• Psychology
• Endocrinology

Background:

• Internet Use Disorder (IUD) is a growing global concern, characterized by loss of control over internet usage and social problems.
• While not an official diagnosis, IUD is increasingly viewed as a behavioral addiction with known fronto-striatal-limbic dysfunctions.
• The molecular underpinnings of IUD, particularly hormonal influences, remain less understood.

Purpose of the Study:

• To investigate the influence of prenatal testosterone, assessed via the 2D:4D digit ratio, on Internet Use Disorder (IUD).
• To explore potential sex differences in the association between prenatal testosterone and IUD, including Internet Gaming Disorder (IGD).

Main Methods:

• Utilized the 2D:4D hand digit ratio as a marker for prenatal testosterone exposure in 217 participants.
• Examined associations between the 2D:4D ratio and both generalized IUD and specific forms like IGD.
• Analyzed data for the whole sample and specific subsamples (males and females).

Main Results:

• A higher right-hand 2D:4D ratio (indicating lower prenatal testosterone) was associated with lower levels of Internet Gaming Disorder (IGD) in the overall sample.
• This association was primarily driven by the 'loss of control' aspect of Internet Gaming Disorder.
• A negative association was also observed between generalized IUD's 'loss of control' and the right 2D:4D ratio in males.

Conclusions:

• The 2D:4D digit ratio serves as a potential biomarker for understanding the biological underpinnings of Internet addiction.
• Prenatal testosterone levels may play a role in the development and manifestation of Internet Use Disorder, including specific forms like IGD.
• Further research incorporating the 2D:4D marker can enhance our understanding of the neurobiological factors contributing to problematic internet usage.