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Subclinical elevation of plasma C-reactive protein and illusions/hallucinations in subjects with Parkinson's disease:
Hideyuki Sawada1, Tomoko Oeda1, Atsushi Umemura1
1Clinical Research Center and Department of Neurology, National Hospital of Utano, Kyoto, Japan.
Background:
Though infections are associated with psychotic symptoms, whether or not subclinical inflammation is associated with hallucinations is not known in Parkinson's disease (PD).
Purpose:
To investigate the association of illusions/hallucinations and plasma CRP levels in PD patients without symptomatic infections.
Methods:
PD patients not diagnosed as having infections were assessed for illusions and hallucinations using the Parkinson Psychosis Questionnaire (PPQ). It comprises four-domain questions: PPQ-A for sleep problems, PPQ-B for hallucinations/illusions, PPQ-C for delusions, and PPQ-D for disorientation. Assigning patients with ≥1 points in the PPQ-B score to be cases and others as controls, the association of hallucinations/illusions and clinical features (age, sex, duration of PD, Unified Parkinson's Disease Rating Scale part 3 (UPDRS-3), Mini-Mental State Examination (MMSE) score, sleep disturbance (PPQ-A score) as well as daily doses of L-Dopa, dopamine agonists, amantadine, and selegiline) were analyzed using a case-control design.
Results:
A total of 111 patients were examined and plasma CRP levels were <0.1-6.0 mg/L. Hallucinations or illusions were detected in 28 (25.2%). There were significant differences in age, UPDRS-3 score, MMSE score, PPQ-A, daily doses of L-Dopa and dopamine agonists and plasma CRP levels between cases and controls. A multivariate logistic regression model revealed that UPDRS-3 scores and plasma CRP levels were significantly associated with hallucinations/illusions with an adjusted odds ratio of 1.96 (95% confidence interval (CI) 1.20-3.20) per 10 points and 1.57 (95% confidence interval 1.13-2.16) per two-fold, respectively. Dividing patients into thirds by CRP levels (≤0.2, 0.3-0.6, ≥0.7 mg/L), the prevalence of hallucinations/illusions was 13.2%, 21.6%, and 41.7%, in the bottom-, middle-, and top-thirds, respectively (for trend p = 0.012).
Conclusions:
Subclinical elevation of plasma CRP levels was associated with hallucinations or illusions after adjustment for motor disability, suggesting that subclinical elevations of CRP levels might be an independent risk for hallucinations/illusions.
Insights
Subclinical inflammation, indicated by elevated C-reactive protein (CRP) levels, is linked to hallucinations and illusions in Parkinson's disease (PD) patients without infections. This suggests CRP may be an independent risk factor for these psychotic symptoms in PD.
Area of Science:
- Neurology
- Neuroinflammation
- Psychiatry
Background:
- Infections are known to cause psychotic symptoms.
- The association between subclinical inflammation and hallucinations in Parkinson's disease (PD) remains unclear.
- This study investigates subclinical inflammation markers in PD patients experiencing hallucinations.
Purpose of the Study:
- To determine the relationship between plasma C-reactive protein (CRP) levels and the occurrence of illusions/hallucinations.
- To examine PD patients who do not have symptomatic infections.
Main Methods:
- 111 Parkinson's disease patients without infections were assessed for hallucinations/illusions using the Parkinson Psychosis Questionnaire (PPQ).
- Patients scoring ≥1 on the PPQ-B (hallucinations/illusions domain) were classified as cases; others were controls.
- Case-control analysis correlated hallucinations/illusions with clinical features, including plasma CRP levels, using logistic regression.
Main Results:
- Hallucinations or illusions were present in 25.2% of the 111 PD patients.
- Elevated plasma CRP levels were significantly associated with hallucinations/illusions (OR 1.57 per two-fold increase).
- Prevalence of hallucinations/illusions increased with higher CRP tertiles (13.2% to 41.7%).
Conclusions:
- Subclinical elevation of plasma CRP levels is associated with hallucinations/illusions in PD patients.
- Elevated CRP may represent an independent risk factor for hallucinations/illusions in Parkinson's disease.
- This finding highlights the potential role of neuroinflammation in PD-related psychosis.
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