An investigation of the effects of age and stroke on implicit motor imagery as demonstrated by a hand laterality judgment test

Sapsford, Frances Jane and Donovan, Tim (2020) An investigation of the effects of age and stroke on implicit motor imagery as demonstrated by a hand laterality judgment test. PhD thesis, Lancaster University.

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Abstract

Background Explicit motor imagery is recommended for stroke rehabilitation but can be difficult to practice. Hand Laterality Judgement (HLJ) stimulates implicit motor imagery which may be easier for stroke patients, but its benefits are unknown. Previous studies are inconclusive and have not considered the effects of older age. Objectives. This thesis investigated the effects of older age and stroke on HLJ and the effects of practising HLJ after a stroke. Methods Three experiments were undertaken. The first compared HLJ in twenty young, healthy participants (mean=22(2) years) with twenty aged 60 -70 years (mean=67(3) years) and twenty-two aged ≥ 70 years (mean=77(5) years). The second compared HLJ of eleven stroke survivors aged ≥ 60 years (mean =69 (6)) with age-matched controls. The third examined the effects of practising HLJ in four stroke survivors. Main findings There were no significant differences in HLJ response times between the young and older groups (p=.06) or between the stroke and control group (p=.13). Both older groups were significantly less accurate than the younger group (young group =92%; older groups= 81%-86% p≤ .00). There were no significant differences in accuracy between the two older groups (P=.10) or between the stroke and control groups (p=.59). All groups engaged in implicit motor imagery, but this was impaired by early old age. Visuospatial imagery was impaired in later old age and by stroke. There were no significant relationships between HLJ performance and upper limb impairment post-stroke. There were no significant effects of practising HLJ, but trends towards increased accuracy (d=.24) and slower response times (d=.46). Conclusion. Stroke survivors can perform HLJ as well as similarly aged healthy individuals. Stroke may impair visuospatial imagery, but accuracy improves with practice. Further research is needed to determine if there are any benefits to post-stroke upper limb rehabilitation.