Suzuki K, et al. - In patients with neurodegenerative diseases, researchers studied serum insulin-like growth factor (IGF)-1 levels and assessed if these levels correlated with clinical parameters. One hundred and fifty-six neurodegenerative disease patients had their serum IGF-1 levels measured in this investigation. Investigators found that serum IGF-1 levels in patients with Parkinson's disease (PD) had a negative correlation with age and modified Rankin scale (mRS) scores; PD had a positive correlation to the striatal dopamine transporter-specific binding ratio and the frontal assessment battery score. Findings revealed that serum IGF-1 levels were negatively linked to age, duration of disease, and mRS scores in patients with Alzheimer's disease (AD). In PD patients and with disability in AD patients, correlations of serum IGF-1 levels with frontal lobe and striatal dopaminergic function and disability were found.