Subjective Cognitive Complaints in Cognitively Normal Patients With Parkinson?s Disease: A Systematic Review

Subjective cognitive complaints (SCCs) refer to self-perceived cognitive decline and are related to objective cognitive decline. SCCs in cognitively normal individuals are considered a preclinical sign of subsequent cognitive impairment due to Alzheimer's disease, and SCCs in cognitively normal patients with Parkinson's disease (PD) are also gaining attention. The aim of this review was to provide an overview of the current research on SCCs in cognitively normal patients with PD. A systematic search found a lack of consistency in the methodologies used to define and measure SCCs. Although the association between SCCs and objective cognitive performance in cognitively normal patients with PD is controversial, SCCs appear to be predictive of subsequent cognitive decline. These findings support the clinical value of SCCs in cognitively normal status in PD; however, further convincing evidence from biomarker studies is needed to provide a pathophysiological basis for these findings. Additionally, a consensus on the definition and assessment of SCCs is needed for further investigations.

Automated summary

Subjective cognitive complaints (SCCs), self-perceived cognitive decline, are related to objective cognitive decline. SCCs in cognitively normal individuals serve as a preclinical sign of subsequent cognitive impairment due to Alzheimer's disease. This review highlights the current research on SCCs in cognitively normal patients with Parkinson's disease, emphasizing the need for coherence in defining and assessing SCCs, and the value of SCCs in predicting cognitive decline. It also calls for further biomarker studies to establish the underlying pathological basis for these findings.