The relation between cognition and motor dysfunction in drug‐naive newly diagnosed patients with Parkinson's disease

Abstract

Recent studies have reported cognitive decline to be common in the early phase of Parkinson's disease. Imaging data connect working memory and executive functioning to the dopamine system. It has also been suggested that bradykinesia is the clinical manifestation most closely related to the nigrostriatal lesion. Exploring the relationship between motor dysfunction and cognition can help us find shared or overlapping systems serving different functions. This relationship has been sparsely investigated in population-based studies of untreated Parkinson's disease. The aim of the present study was to investigate the association between motor signs and cognitive performance in the early stages of Parkinson's disease before the intake of dopaminergic medication. Patients were identified in a population-based study of incident cases with idiopathic parkinsonism. Patients with the postural instability and gait disturbances phenotype were compared with patients with the tremor-dominant phenotype on demographics and cognitive measures. Associations between cognitive and motor scores were investigated, with age, education, and sex controlled for. Bradykinesia was associated with working memory and mental flexibility, whereas axial signs were associated with episodic memory and visuospatial functioning. No significant differences in the neuropsychological variables were found between the postural instability and gait disturbances phenotype and the tremor phenotype. Our results indicate a shared system for slow movement and inflexible thinking that may be controlled by a dopaminergic network different from dopaminergic networks involved in tremor and/or rigidity. The association between axial signs and memory and visuospatial function may point to overlapping systems or pathologies related to these abilities.

Paired Studies Comparing Clinical Profiles of Lewy Body Dementia with Alzheimer’s and Parkinson’s Diseases

“…Some investigators include speech and facial expression (bulbar features) or neck rigidity as additional axial motor items [25][26][27]. In our study, LBD subjects, while matched for UPDRS III total score, did significantly worse than the PD subjects on only PIGD items (Table 2).…”

“…The pattern of cognitive deficits in PDD and DLB, however, appears to differ in significant ways from that of AD [4-7, 9, 10, 23]. Furthermore, evidence suggests that there are specific relationships between motor and gait impairment patterns and the type of cognitive impairment or dementia condition present [1,2,[24][25][26][27][28][29][30].…”

“…We designated specific components of the UPDRS III into the following subsections that have been reported commonly in the literature: axial Postural Instability and Gait Difficulty (PIGD; arising from chair, posture, gait, and postural stability), axial bulbar (speech, facial expression), and bradykinesia (hand movement, rapid alternating movements of hands, leg agility, body bradykine-sia) [25]. Each subject underwent cognitive, gait, and mobility evaluations.…”

“…The items of the UPDRS III that include arising from a chair, posture, gait, and postural stability have been referred to as axial PIGD items [25]. Some investigators include speech and facial expression (bulbar features) or neck rigidity as additional axial motor items [25][26][27].…”

Contributions of mild parkinsonian signs to gait performance in the elderly

“…In early stages of PD, bradykinesia has been correlated with working memory and executive functioning, whereas rigidity and tremor were not correlated with any cognitive measures (Domellof et al 2011). Fleischman et al (2005 found no specific relationship between MPS and cognitive performance in a cohort of older adults without PD.…”