Relationship between motor reserve, thalamus volume, working memory and information processing speed in older adults

This study aimed to investigate the relationship between the motor reserve, volume of the thalamus and working memory, as well as the role of information processing speed, in older adults. 44 participants, aged 65 to 85 (M = 71.25, SD = 5.18, 22.7% male), with no self-reported on-going neurological, oncological or psychiatric diseases, were included in the study. The data on physical activity was obtained with the Social Determinants of Health Behaviour questionnaire (FINBALT, 2008), and the motor reserve index was calculated. For working memory measures, the Numbers Reversed task was used (Woodcock et al., 2001). Information processing speed was assessed with Handball Goalie task (Molotanovs, 2013) and MRI data were obtained with Siemens 1.5T and analyzed with Freesurfer software. Data were analyzed with Spearman's rho and indicated a statistically significant relationship between the motor reserve index and thalamus (r = .324, p = .038), while thalamus positively correlated with working memory scores (r = .347, p = .021). There were no significant relationships between the rest of the variables. As the literature has indicated a role of information processing speed in such executive functions as working memory, a partial correlation analysis was conducted and the results indicated that the information processing speed significantly improved the association between both - working memory and thalamus, as well as motor reserve (r = .425, p = .005 and r = .255, p = .099). The results indicate that greater thalamus volume could be related to better motor reserve, as well as better working memory results; however, the association between the variables could be modified by information processing speed. Further studies would be beneficial to better understand the role of motor reserve and information processing speed in cognitive functioning and brain health.