Digit ratio (2D:4D) in relation to substance and computer use: a meta-analysis

Area of Science:

• Endocrinology
• Psychology
• Behavioral Science

Background:

• The second to fourth digit ratio (2D:4D) is a recognized marker for prenatal androgen exposure.
• Previous research on the association between 2D:4D ratio and substance or computer use has yielded inconsistent results.
• Understanding potential biological correlates of addiction risk is crucial for developing targeted interventions.

Purpose of the Study:

• To conduct a meta-analysis quantifying the relationship between 2D:4D ratio and substance or computer use.
• To investigate moderating factors including sex, definition of caseness, addiction type, and hand measured.
• To explore the link between prenatal hormone exposure and addiction vulnerability.

Main Methods:

• A random-effects meta-analysis was performed on 18 independent samples comprising 175,955 participants.
• Meta-regression analyses were used to test for moderators.
• Data were analyzed for combined samples, males, females, and specific subgroups based on dependency and substance/computer use type.

Main Results:

• A significant association was found between lower 2D:4D ratio and substance/computer use in the combined sample and specifically in males, but not in females.
• The association was stronger in studies comparing dependent versus non-dependent individuals.
• Alcohol intake and computer use showed significant differences in 2D:4D ratio, particularly in dependent males.

Conclusions:

• This meta-analysis confirms that a lower 2D:4D ratio is associated with substance and computer dependency.
• The findings highlight a potential sex-specific biological influence on addiction risk.
• Further research is warranted to elucidate the role of the intrauterine hormonal environment in addiction development.