Rate of cognitive decline in premotor Parkinson's disease: A prospective study (NEDICES)

Abstract

Previous research has documented cognitive impairment in the early stages of Parkinson's disease (PD). It is not known when this decline starts or if decline progresses at an accelerated rate during the premotor period of the disorder. In this population-based prospective study of older people (≥65 years) from the Neurological Disorders in Central Spain (NEDICES) cohort, we compared the rates of cognitive decline in 3 groups: (1) non-PD elderly controls; (2) prevalent PD patients (those diagnosed with the disease at baseline, 1994-95); and (3) premotor PD subjects (those diagnosed with the disease at follow up, 1997-98, but not at baseline). A 37-item version of the Mini-Mental State Examination (37-MMSE) was administered in the 2 visits of the study. From 2487 participants (age, 72.8 ± 6.0 years), including 2429 controls, we recruited 21 premotor PD cases, and 37 prevalent PD cases. At baseline, the mean 37-MMSE score was 28.5 ± 4.7 in prevalent cases, 28.1 ± 4.6 in premotor cases, and 29.9 ± 5.0 in controls (P = .046). During the 3-year follow-up period, there was a significant score decline of 2.4 ± 4.6 points in prevalent cases versus 0.2 ± 4.1 points in premotor cases and 0.3 ± 4.0 points in controls (Kruskal-Wallis test, P = .03). In the NEDICES cohort, cognitive test scores of prevalent PD cases declined at a rate above and beyond that observed in premotor PD cases and in controls. The rate of cognitive decline in premotor PD and controls was similar. Our data suggest that a decline in global cognitive function does not occur in premotor PD.

Substantia nigra hyperechogenicity is related to decline in verbal memory in healthy elderly adults

“…These changes in cognition in the course of neurodegeneration can be traced back to the prodromal stages. Although no global decline is reported , subtle impairment in specific domains was found in the prodromal stage . Furthermore, two strong studies recently demonstrated that memory problems may precede the motor symptoms by 2 years in patients with PD .…”

Neuropsychiatric symptoms in untreated Parkinson’s disease

“…The rate of cognitive decline in the premotor phase of PD compared to controls is similar based on two population-based studies,173,174 suggesting that global cognitive dysfunction may not occur in premotor PD. Generally, in PD, ~25% of nondemented patients have mild cognitive impairment (MCI)175 and up to 80% of all PD patients will eventually develop dementia 176.…”

Cognitive changes in prodromal Parkinson's disease: A review

“…In the smaller population‐based Neurological Disorders in Central Spain study, changes in global cognitive function were prospectively documented over time. They were compared with 37 prevalent PD patients (diagnosed with PD at baseline), 21 premotor PD patients (diagnosed with incident PD at follow‐up 3.4 ± 0.5 years after baseline), and 2429 control participants (not diagnosed with PD at baseline or at follow‐up).…”