The effects of acute dopamine reuptake inhibition on cognitive function during passive hyperthermia

Dopamine activity can modulate physical performance in the heat, but less is known about its effects on cognition during thermal stress. Twelves males completed a randomized, double-blinded protocol consisting of oral ingestion of 20 mg of methylphenidate (MPH) or placebo (lactose pill) during passive heating using a water-perfused suit (water temperature ∼49 °C). To identify the impact of peripheral versus central thermal strain, a cognitive test battery was completed at 4 different thermal states: baseline (BASE; 37.2 ± 0.6 °C core, 32.9 ± 0.7 °C skin), neutral core-hot skin (NC-HS; 37.2 ± 0.3 °C, 37.4 ± 0.3 °C), hyperthermic core-hot skin (HC-HS; 38.7 ± 0.4 °C, 38.7 ± 0.2 °C), and hyperthermic core-cooled skin (HC-CS; 38.5 ± 0.4 °C, 35.1 ± 0.8 °C). The cognitive test battery consisted of the 2-back task (i.e., working memory), set-shifting (i.e., executive function), Groton Maze Learning Task (i.e., executive function) and detection task (i.e., psychomotor processing). MPH led to significantly higher heart rates (∼5-15 b·min^-1) at BASE, NC-HS, and HC-HS (all p < 0.05). There were no significant differences in the number of errors made on each task (all p < 0.05). Participants were significantly faster (p < 0.05) on the set-shifting task in the HC-HS timepoint, irrespective of drug condition (p > 0.05). In summary, we demonstrated that 20 mg of MPH did not significantly alter cognitive function during either normothermia or moderate hyperthermia. Novelty: Twenty milligrams of MPH did not significantly alter cognitive function during passive heat stress. MPH led to significant higher heart rates (∼5-15 b·min^-1) in thermoneutral and during passive heat stress. Future studies are needed to determine the mechanisms of why MPH improves physical but not cognitive performance during heat stress.

Results From a Feasibility Study of Square-Stepping Exercise in Older Adults With Type 2 Diabetes and Self-Reported Cognitive Complaints to Improve Global Cognitive Functioning

OBJECTIVES

Adults with type 2 diabetes mellitus have an increased risk for dementia. Therefore, we proposed an intervention called the Square-stepping exercise (SSE) program to mitigate this risk. Our primary aim was to determine the feasibility of SSE in adults with type 2 diabetes and self-reported cognitive complaints. Our secondary aim was to determine whether 24 weeks of SSE improved cognition. Our tertiary aim was to determine whether SSE improved antisaccade reaction time, which is a measure of executive-related oculomotor control.

METHODS

Adults >49 years with type 2 diabetes and self-reported cognitive complaints were randomized to an SSE group (2×/week for 24 weeks of SSE) or a control group. Feasibility was assessed by recruitment and attendance. Participants were assessed at baseline, after 12 weeks and after 24 weeks for global cognitive function, memory, planning, reasoning and concentration via a computer-based cognitive battery (Cambridge Brain Sciences) and antisaccade reaction time (at baseline and 24 weeks).

RESULTS

Participants in the SSE group were (mean [SD]): 65.9 (5.2) years old; 33% female; body mass index 33.3 kg/m² (4.8) (n=12). Participants in the control group were 71.2 (6.9) years old; 31% female; body mass index 31.9 kg/m² (4.6) (n=13). Over 24 weeks, attendance was 70.2% (SD 17.2) for 4/12 participants. There were 4 withdrawals and 1 adverse event. There were no differences in global cognitive functioning. The SSE group improved in planning domain change scores between 12 and 24 weeks (F=5.8, p=0.03, η_p²=0.28) compared to controls. In the SSE group, we found a nonsignificant improvement in antisaccade reaction time of 38 ms (SD 16), n=2, compared to 9 ms (SD 45) in the control group, n=8.

CONCLUSIONS

SSE should be evaluated further to improve its feasibility in older adults with type 2 diabetes. This study provides preliminary evidence that SSE improves executive function in adults with type 2 diabetes and self-reported cognitive complaints.

MATERNAL DEPRESSION AND THE DEVELOPMENT OF EXECUTIVE FUNCTION AND BEHAVIOR PROBLEMS IN HEAD START: INDIRECT EFFECTS THROUGH PARENTING

The present study used a large, nationally representative sample of Head Start children (N=3,349) from the Family and Child Experiences Survey of 2009 (FACES) to examine associations among maternal depression (measured when children were ˜36 months old) and children's executive function (EF) and behavior problems (measured when children were ˜48 months old). Preliminary analyses revealed that 36% of mothers in the sample had clinically significant levels of depressive symptoms. Furthermore, a path analysis with demographic controls showed a mediation effect that was significant and quite specific; mother-reported warmth (and not mother-child reading) mediated the path between maternal depression, children's EF, and behavior problems. Findings provide empirical support for a family process model in which warm, sensitive parenting supports children's emerging self-regulation and reduces the likelihood of early onset behavior problems in families in which children are exposed to maternal depression.

Four minutes of in-class high-intensity interval activity improves selective attention in 9- to 11-year olds

The amount of time allocated to physical activity in schools is declining. Time-efficient physical activity solutions that demonstrate their impact on academic achievement-related outcomes are needed to prioritize physical activity within the school curricula. "FUNtervals" are 4-min, high-intensity interval activities that use whole-body actions to complement a storyline. The purpose of this study was to (i) explore whether FUNtervals can improve selective attention, an executive function posited to be essential for learning and academic success; and (ii) examine whether this relationship is predicted by students' classroom off-task behaviour. Seven grade 3-5 classes (n = 88) were exposed to a single-group, repeated cross-over design where each student's selective attention was compared between no-activity and FUNtervals days. In week 1, students were familiarized with the d2 test of attention and FUNterval activities, and baseline off-task behaviour was observed. In both weeks 2 and 3 students completed the d2 test of attention following either a FUNterval break or a no-activity break. The order of these breaks was randomized and counterbalanced between weeks. Neither motor nor passive off-task behaviour predicted changes in selective attention following FUNtervals; however, a weak relationship was observed for verbal off-task behaviour and improvements in d2 test performance. More importantly, students made fewer errors during the d2 test following FUNtervals. In supporting the priority of physical activity inclusion within schools, FUNtervals, a time efficient and easily implemented physical activity break, can improve selective attention in 9- to 11-year olds.