Prevalence and affective correlates of subjective cognitive decline in patients with de novo Parkinson's disease

OBJECTIVES: The novel concept of subjective cognitive decline (SCD) in Parkinson's disease (PD) refers to subjective cognitive impairment without concurrent objective cognitive deficits. This study aimed to determine the prevalence and affective correlates of SCD in de novo PD patients. MATERIALS AND METHODS: A total of 139 de novo PD patients underwent comprehensive neuropsychological evaluation. PD patients with SCD (PD‐SCD) did not meet the diagnostic criteria for mild cognitive impairment in PD (PD‐MCI) based on the Movement Disorder Society Level II Criteria and were defined by a Domain‐5 Score ≥1 on the Non‐Motor Symptoms Questionnaire. Affective symptoms were measured using the Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA). RESULTS: In de novo PD cohort, the prevalence of SCD was 28.1%. PD‐SCD patients performed significantly better than PD‐MCI patients on tests of five cognitive domains. The more commonly affected domains in PD‐SCD patients were memory (28.2%) and attention/working memory (25.6%). Multivariable linear regression analysis revealed that PD‐SCD was significantly associated with both HAMD (β = 4.518, 95% CI = 0.754–8.281, p = .019) and HAMA scores (β = 4.259, 95% CI = 1.054–7.464, p = .010). Furthermore, binary logistic regression analysis revealed that higher HAMD (OR = 1.128, 95% CI = 1.019–1.249, p = .020) and HAMA scores (OR = 1.176, 95% CI = 1.030–1.343, p = .017) increased the risk of PD‐SCD. CONCLUSIONS: Our findings suggest that SCD is highly prevalent in de novo PD patients. The presence of PD‐SCD is suggestive of an underlying affective disorder.