Serum insulin-like growth factor-1 levels in neurodegenerative diseases.

BACKGROUND: We investigated serum insulin-like growth factor (IGF)-1 levels in patients with neurodegenerative diseases and correlated these levels with clinical parameters. METHODS: One hundred and fifty-six patients with neurodegenerative diseases were included in this study, and serum IGF-1 levels were determined. RESULTS: Serum IGF-1 levels (mean ± standard error) were not significantly different among the patients with different neurodegenerative diseases: Parkinson's disease (PD; n = 73), 112.1 ± 5.1 ng/mL; progressive supranuclear palsy (n = 15), 102.9 ± 8.3 ng/mL; multiple system atrophy (n = 22), 103.1 ± 37.6 ng/mL; Alzheimer's disease (AD; n = 18), 102.2 ± 9.4 ng/mL; amyotrophic lateral sclerosis (n = 6), 105.5 ± 27.4 ng/mL; dementia with Lewy bodies (n = 14), 82.4 ± 7.4 ng/mL; frontotemporal dementia (n = 6), 90.0 ± 17.0 ng/mL; and corticobasal syndrome (n = 2), 118.0 ± 14.0 ng/mL. In patients with PD, serum IGF-1 levels were negatively correlated with age and modified Rankin scale (mRS) scores and positively correlated with the striatal dopamine transporter-specific binding ratio and the frontal assessment battery score. In patients with AD, serum IGF-1 levels were negatively correlated with age, disease duration, and mRS scores. CONCLUSION: We found correlations of serum IGF-1 levels with frontal lobe and striatal dopaminergic function and disability in PD patients and with disability in AD patients. The usefulness of measuring serum IGF-1 levels for monitoring disease progression in neurodegenerative diseases requires further studies.