The Brain Breaks study

In recent years, the role of physical activity in healthy brain ageing has been an emerging topic of investigation. Given there is currently no targeted pharmacotherapy to reduce the risk of cognitive decline and dementias, there is a clear need to investigate modifiable behavioural risk factors (particularly related to physical inactivity).

Adopting regular exercise is a good strategy to improve cognitive function, especially in older adults at risk of dementia. One study showed that a six month physical activity intervention, where participants aimed for 150 minutes of moderate to vigorous intensity exercise per week, was effective at imparting cognitive benefits over an 18-month follow-up period (Lautenschlager et al., 2008).

Nonetheless, even when this level of physical activity is achieved, it is common to accumulate 7-10 hours of total sitting during waking hours (Healy et al., 2008). There is an increased risk for cardiovascular disease and all-cause mortality associated with this excessive sitting, which remains even after accounting for leisure time physical activity (Owen et al., 2010).

Little is known about the effect of sitting on cognitive function. Observational evidence has shown TV viewing time, as a surrogate measure of sitting time, to be adversely associated with vitality as well as physical and mental wellbeing (Dempsey et al., 2014), but also adversely associated with cognitive function (Kesse-Guyot et al., 2012).

Evidence suggests that in an acute setting of eight hours, breaking up prolonged sitting confers metabolic benefits (Dunstan et al., 2012). Whether this acute effect of breaking up sitting includes cognitive benefits, is a question which remains to be answered. A single acute bout of exercise, however, has been shown to improve cognitive function (Joyce et al., 2009).

The mechanisms underpinning the beneficial effects of exercise on cognitive function still remain unclear. Evidence supports the role of vascular adaptation to exercise, in being crucial to mediating the beneficial health effects of exercise (Green, 2009). This vascular adaptation resulting in increased brain blood flow may mediate the cognitive benefits of exercise (Davenport et al., 2012).

The Brain Breaks study will expand on this evidence and investigate whether, compared to uninterrupted sitting, there are acute effects of a single bout of moderate-intensity exercise, with or without intermittent (three minutes) light-intensity breaks from prolonged sitting, on cognitive function (primary outcome) and brain blood flow (secondary outcome) in older/overweight adults (55-80 years). A within-subjects experimental design will be used to compare three conditions, each lasting eight hours with at least seven days washout between conditions. The three conditions are:

• Uninterrupted sitting lasting eight hours
• 30 minutes of moderate intensity exercise, followed by uninterrupted sitting
• 30 minutes of moderate intensity exercise, followed by interrupted sitting (three-minute walking break every 30 minutes)

The Brain Breaks study will provide crucial evidence that can inform recommendations on realistic lifestyle changes that improve cognitive function.

For more background information, see the suggested readings below.