The influence of motor and non‐motor characteristics of Parkinson's disease on motor imagery vividness

Motor imagery (MI) can facilitate movement in healthy individuals and patient populations. People with Parkinson's (PwP) experience debilitating motor symptoms, yet appear to have relatively intact MI capabilities, which may position MI as an effective therapeutic adjunct to existing interventions for PwP. However, individual differences in healthy individuals, such as cognitive factors and depression, as well as symptom severity in PwP, have been shown to influence MI, which may moderate its therapeutic impact. In the present study, data from 56 PwP were analysed using linear mixed-effect modelling to explore whether motor symptoms, cognitive function and depression were associated with MI vividness. Overall motor symptom severity was not associated with MI vividness, and specific symptoms (bradykinesia and tremor) did not show consistent relationships. This suggests that individual differences in symptom expression may make it difficult to identify a clear relationship between MI and motor symptoms. Action fluency (verb generation) was positively associated with right-lateralised MI vividness. However, working memory, general language fluency and depression were not associated with MI vividness. The relationship between generating verbs and MI vividness is consistent with theories of grounded and embodied cognition. Action fluency could thus potentially be used to predict the effectiveness of MI-based interventions in PwP.