Associations between movement and acceptance of an effortful cognitive task in participants with low mood

The link between physical activity (PA) and cognition has been documented across various populations, with acute and chronic benefits of PA reported [1] alongside protective effects against cognitive decline [2]. Impaired cognition in depression has been hypothesised to be linked to motivational impairment, effort-based decision making, and reward sensitivity [3]. This study investigated the link between PA (measured by overall daily activity, and intensity of activity) and motivation, indexed by willingness to engage in cognitive effort challenges with varying reward and difficulty, in participants with low mood using a cross-sectional design. PA levels were measured via wrist worn accelerometers with participants at the pre-randomisation phase of a physical activity intervention.

In N=113 participants with at least mild low mood (mean PHQ-9 = 10.38, SD = 5.13, mean age = 26.77, SD = 9.11), activity data recorded via accelerometry was assessed alongside a cognitive effort task with four levels of reward and difficulty. On each trial, participants could accept or reject the effort challenge (categorising a series of 10 digits as odd and even), with difficulty manipulated using the number of switches required [4]. All accelerometry data included had over six days of total wear time, with at least sixteen hours worn per day. Using multilevel regression, we modelled the probability of acceptance (p_acceptance) at each reward and difficulty level, and included variables indexing each activity measure (overall activity level via daily steps, and higher-resolution metrics of activity via sleep, light, moderate and vigorous PA; averaged over days), in separate models.

A significant interaction between reward and activity measures on p_acceptance was observed for steps (F(3,1665) = 3.88, p = .009), minutes of sedentary behaviour (F(3, 1665) = 8.42, p<.001), and number of minutes of vigorous activity (F(3,1665) = 4.51, p = .004), whilst time spent engaged in moderate and light activity showed no significant effects. Additionally, a similar interaction was observed between reward and sleep quantity (F(3, 1665) = 5.94, p<.001). Greater levels of activity and sleep were associated with greater propensity to exert effort as reward increased, whilst no significant main effects or interactions with task difficulty were found for any activity measures.

These preliminary findings emphasise the link between PA and motivation. Potential implications regarding the key components and most potent intensities of PA driving this relationship are also raised. Various significant interactions were observed between reward and PA measures, but not task difficulty, suggesting the potential primacy of reward sensitivity. Although average steps significantly interacted with reward for p_acceptance, the most and least intense subtypes of movement appeared to drive the effect, with only sedentary and vigorous activity showing significant interactions. Preliminary evidence of sleep volume interacting with reward sensitivity similarly raises the question of the potential efficacy of interventions focused on either PA or sleep in modulating motivation.

References

1. Ratey, J. J. & Loehr, J. E. The positive impact of physical activity on cognition during adulthood: a review of underlying mechanisms, evidence and recommendations. 22, 171–185 (2011).
2. Guure, C. B., Ibrahim, N. A., Adam, M. B. & Said, S. M. Impact of Physical Activity on Cognitive Decline, Dementia, and Its Subtypes: Meta-Analysis of Prospective Studies. BioMed Res. Int. 2017, 9016924 (2017).
3. Hird, E. J., Slanina-Davies, A., Lewis, G., Hamer, M. & Roiser, J. P. From movement to motivation: a proposed framework to understand the antidepressant effect of exercise. Transl. Psychiatry 14, 273 (2024).
4. Fleming, H., Robinson, O. J. & Roiser, J. P. Measuring cognitive effort without difficulty. Cogn. Affect. Behav. Neurosci. 23, 290–305 (2023).