Is C-reactive protein level a marker of advanced motor and neuropsychiatric complications in Parkinson's disease?

C-reactive protein (CRP) is a plasma protein involved in inflammation. While its levels have been associated with stroke, cognitive impairment and depression, the association with clinical characteristics of Parkinson's disease (PD) is unknown. A total of 73 consecutive patients with PD (46 males, age 68.8 ± 11.5 years) were evaluated regarding motor as well as cognitive and psychiatric features of PD. Plasma CRP levels were determined and tests for associations with disease parameters were performed. The average level of CRP was 3.9 ± 4.1 μmol/L, and 45.2% of the patients (n = 33) had a level above 3.0 μmol/L. Patients in the high CRP group tended to be older (71.4 ± 9.2 vs. 66.7 ± 12.9 years; p = 0.08) and coronary artery disease (CAD) was more common (36 vs. 10%, p < 0.05) in the high CRP group, but no differences were found between the groups regarding gender, disease duration, levodopa dose, motor scores or most of the neuropsychiatric complications such as severity of depression, psychosis, dementia, cognitive decline or frontal lobe dysfunction. Reported depression (at present or in the past) was more common in the high CRP group (54.5 vs. 25%, p = 0.01). CRP levels in patients with PD are associated with a higher prevalence of CAD, but are not associated with PD duration or severity, or with neuropsychiatric complications other than reported depression.