Frequency and Correlates of Subjective Memory Complaints in Parkinson’s Disease with and without Mild Cognitive Impairment: Data from the Parkinson’s Disease Cognitive Impairment Study

Abstract

Subjective memory complaints (SMC) may represent the preclinical phase of mild cognitive impairment (MCI) due to Alzheimer's disease. Dementia/MCI have been described with a high prevalence in Parkinson's disease (PD), but whether SMC may predict the development of cognitive impairment has been barely explored. To evaluate the frequency and clinical correlates of isolated SMC (PD-SMC) or within the construct of MCI in subjects with PD, 147 PD patients from the PArkinson's disease COgnitive impairment Study (PACOS) were consecutively recruited for the study. This is a multicenter study involving two Movement Disorder Centers in south Italy. All subjects underwent comprehensive neuropsychological evaluation and PD-MCI was diagnosed according to Litvan's criteria. The Memory Assessment Clinics Questionnaire was used to assess SMC. Logistic regression analysis, adjusted for demographics and significant covariates, was used to evaluate clinical differences between groups. Forty-two (28.6%) individuals presented with PD without SMC and/or MCI (PDw), 40 (27,2%) with PD-SMC, 48 (32,6%) PD-SMC-MCI, and 17 (11,6%) PD-MCI without SMC (PD-MCI). When compared to PDw, PD-SMC was significantly associated with anxiety (OR = 3.93, 95% CI = 1.18-13.03), while PD-SMC-MCI related to motor progression (OR = 5.29, 95% CI = 1.12-24.86), and instrumental disability (OR = 6.98, 95% CI = 2.08-23.38). About 60% of patients showed SMC, in isolation or within the MCI frame. The role of SMC in PD seems to have a different etiology depending on the presence/absence of MCI. In particular, PD-SMC would represent a subjective reaction to the disease, while PD-SMC-MCI would depict motor progression and disability.

Subjective memory decline in Parkinson's disease patients with and without fatigue

“…Furthermore, we detected SMD in 15% of our sample. This prevalence rate is roughly consistent both with that reported in cohorts of de novo untreated [14] as well as in long-standing treated patients with PD [13,18], but lower than that reported in other studies [15]. Several factors may have contributed to the discrepancies in SMD prevalence rate including: 1) tools used for detecting the memory complaints or cognitive deterioration, and 2) sample size.…”

“…The possible association between fatigue and SMD might be consistent with functional neuroimaging data showing that cortical areas associated to fatigue in PD [6][7][8][9] strongly overlap with key regions associated to SMD in PD [16,17]. SMD has a prevalence ranging from 10% to 27% [13][14][15]18], and is tightly related to anxious-depressive symptoms [13,15,[18][19][20][21], and may represent a risk factor for future cognitive decline [14,22] in PD.…”

“…Noteworthy, although none of the present patients met the Diagnostic and Statistical Manual criteria for depression (depression was an exclusion criterion), anxious/depressive symptoms as well as the other behavioural symptoms were more severe in patients with fatigue and could have partially influenced our results (e.g., Refs. [13,15]). Nevertheless, controlling for clinical and behavioural nonmotor symptom measures (by logistic regression analysis), the degree of association between SMD and the diagnosis of fatigue increased (from 5.33 to 5.97), strongly supporting the tight association between these two nonmotor manifestations.…”

“…Indeed, memory complaints in PD might reflect an objective memory decline or be part of a specific clinical condition defined as subjective memory decline T (SMD), i.e. self-experienced persistent decline in memory capacity along with normal age-, gender-, and education-adjusted performance on standardized neuropsychological tests [13][14][15].…”

Cardiovascular autonomic function and MCI in Parkinson's disease

“…A sample of 185 PD patients from the original cohort of the PACOS study [1] was included in the present study based on the following criteria: a comprehensive neuropsychological and neurovegetative assessment to detect cardiac autonomic function. All patients underwent a neurological examination including the administration of the Unified Parkinson's Disease Rating Scale (UPDRS), Hoehn and Yahr scale (HY) and a neuropsychological evaluation as detailed elsewhere [1,4]. Patients were classified in PD with Normal Cognition (PD-NC) or PD-MCI according to the MDS Level II criteria [5].…”