Figure 2.
Patients with Parkinson disease (PD) have higher serum β-hexachlorocyclohexane (β-HCH) levels than controls and patients with Alzheimer disease (AD). Levels of β-HCH in patients with AD are not significantly different from those in controls, which indicates that elevated levels of β-HCH are specific to PD in this sample. Black bars indicate the mean values; red bars, median values.