Different PD-MCI criteria and risk of dementia in Parkinson’s disease: 4-year longitudinal study

Abstract

The Movement Disorder Society Task Force (MDS-TF) has proposed diagnostic criteria for mild cognitive impairment in Parkinson’s disease (PD-MCI). We hypothesized that the risk of dementia (PDD) varies across the different cutoff schemes allowed. A longitudinal study followed 121 non-demented PD patients for up to 4.5 years. In Part One, unique groups of patients were identified as PD-MCI at baseline using the MDS-TF requirement of two impaired cognitive test scores, with both scores classified as impaired at either (i) 2 s.d., (ii) 1.5 s.d. or (iii) 1 s.d. below normative data; relative risk (RR) of PDD was assessed at each criterion. In Part Two, the whole sample was reassessed and (i) RR of PDD determined when two impairments at 1.5 s.d. existed within a single cognitive domain, followed by (ii) RR of PDD in the unique group whose two impairments at 1.5 s.d. did not exist within a single domain (i.e., only across two domains). Twenty-one percent of patients converted to PDD. Part One showed that the 1.5 s.d. criterion at baseline is optimal to maximize progression to PDD over 4 years. Part Two, however, showed that the 1.5 s.d. cutoff produced a high RR of PDD only when two impairments were identified within a single cognitive domain (7.2, 95% confidence interval (CI)=3.4–16.6, P<0.0001; 51% converted). The RR when the 1.5 s.d. impairments occurred only across two different domains, was nonsignificant (1.7, CI=0.5–7.4, P=0.13; 11% converted) and similar to using a 1 s.d. criterion (1.9, CI=0.3–4.3, P=0.13; 8% converted). If the intent of a PD-MCI diagnosis is to detect increased risk of PDD in the next 4 years, optimal criteria should identify at least two impairments at 1.5 s.d. within a single cognitive domain.

Clinical characteristics of cognitive impairment in patients with Parkinson's disease and its related pattern in 18F‐FDG PET imaging

“…The highest percentages of PD patients with impairment (i.e., >2 SDs below control mean) on the individual neuropsychological tests were for TMT-B (20.2%) and TMT-A (19.6%). We also highlighted the clusters that sur- (Caviness et al, 2007;Muslimovic, Post, Speelman, & Schmand, 2005;Wang et al, 2015), the majority of our PD-MCI patients had multipledomain deficits (94.9%), similar to the studies using the MDS Task Force criteria (Goldman, Weis, Stebbins, Bernard, & Goetz, 2012;Wood et al, 2016). We also highlighted the clusters that sur- (Caviness et al, 2007;Muslimovic, Post, Speelman, & Schmand, 2005;Wang et al, 2015), the majority of our PD-MCI patients had multipledomain deficits (94.9%), similar to the studies using the MDS Task Force criteria (Goldman, Weis, Stebbins, Bernard, & Goetz, 2012;Wood et al, 2016).…”

Caregiver burden is increased in Parkinson’s disease with mild cognitive impairment (PD-MCI)

“…While the authors reported significantly lower quality of life scores with regard to physical health and interruptions to usual activities among PD-MCI caregivers, they mention that there was no difference in caregiver burden. They did not, however, report the actual levels of burden, but stated that the results were similar to those of Leroi et al [9] These two studies used level I criteria to establish PD-MCI status, whereas the current study employed the more comprehensive level II criteria, which has been shown to be suitable in terms of stability and increased risk of progression to PDD [4]. Also, level I criteria may underestimate the proportion of PD-MCI patients and thus misclassify some PD-MCI patients as PD-N [31].…”

Cognitive decline in Parkinson disease

“…The distribution of patients in these four groups varies markedly among different studies, depending on factors including the case selection procedures, the criteria applied, the study design (cross-sectional or longitudinal), and the cognitive measurement procedures utilized. A recent study, which attempted to define the optimal criteria for PD-MCI, found that impairment (>1.5 SD below the normative mean) on two tests within the same cognitive domain — rather than across different domains — was the best predictor of progression to dementia during the next 4 years 13 . As highlighted above, the separation between MCI and dementia hinges on whether the functional impact of cognitive impairment is ‘severe enough to impair daily life’, a criterion that is difficult to operationalize and requires an element of clinical judgement.…”