Elevated IGF1 in clinical opiate dependence.

OBJECTIVE: To compare IGF1 levels in opiate dependent and general patients both absolutely and by age.

DESIGN: A naturalistic observational study was undertaken of opiate dependent and general medical patients.

SETTING: Primary care.

PATIENTS: 74 opiate substance use dependent (SUD) patients were compared with 262 non-SUD (NSUD) patients.

RESULTS: (1) Comparative IGF1 levels; (2) age and sex corrected IGF1 levels; (3) IGF1 levels corrected for age, sex, and hepatic and immune biomarkers.

MAIN FINDINGS: The SUD patients were younger (32.60+0.89 vs. 42.49+0.96 years, mean+S.E.M., p<0.0001) and had more males (72.9% and 39.3%, p<0.0001) than the NSUD patients. Restriction of the age range to 15-45 years (70 vs. 153 patients) made the difference in ages non-significant (31.27+0.71 vs. 32.32+0.61 years, p=0.47) but IGF1 remained elevated in SUD (26.56+1.21 vs. 22.65+0.57nmol/L, p=0.0039). When multiple regression was used to correct for the age and sex disparities, the age: addiction interaction remained significantly elevated (p=0.0003). In an additive model opiate dependence showed a 23.8% elevation in IGF1. When the interactive model was further adjusted by the inclusion of ALT and CRP as indices of hepatic inflammation and immune activation respectively, addictive status remained significant both alone (p=0.0134) and in 2-, 3- and 4-way interactions with age, male sex, and ALT (all p<0.0255).

CONCLUSION: These data demonstrate that serum IGF1 is elevated in opiate dependence both absolutely and after adjustment for age, sex, and markers of immune and hepatic activation.

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