Latest Research News
A small study involving 22 students with depression and 30 mentally healthy students had positive results from a program that combines mental training through meditation and physical training through aerobic exercise. After eight weeks, those with depression showed a nearly 40% reduction in depressive symptoms, and said they did not spend as much time worrying about negative situations taking place in their lives as they did before the study began. There were also changes in brain activity that may reflect better cognitive control.
Interestingly, those in the control group also reported fewer depressive symptoms.
The program involved two sessions a week, with each one having 30 minutes of focused attention meditation followed by 30 minutes of aerobic exercise. They were told that if their thoughts drifted to the past or the future they should refocus on their breathing - enabling those with depression to accept moment-to-moment changes in attention.
Alderman, B. L., Olson, R. L., Brush, C. J., & Shors, T. J. (2016). MAP training: combining meditation and aerobic exercise reduces depression and rumination while enhancing synchronized brain activity. Transl Psychiatry, 6, e726. Retrieved from http://dx.doi.org/10.1038/tp.2015.225
Research using data from 2131 participants in the 2008 U.K. Health Survey suggests that regular exercise can partly counteract the negative health effects of being sedentary. The analysis grouped people into the following categories:
- physically active and low sedentary 'busy bees' (18.6% of the sample)
- physically active and high sedentary 'sedentary exercisers' (36.7%)
- physically inactive and low sedentary 'light movers' (6.8%)
- physically inactive and high sedentary 'couch potatoes' (37.9%).
Overall, physical activity was significantly associated with lower BMI, lower waist circumference, lower HbA1c levels (HbA1c is a modified form of haemoglobin, commonly used to measure glucose concentration; higher levels indicate poorer control of blood glucose levels), and higher HDL-cholesterol (the 'good' cholesterol). Sedentary time was associated with lower HDL-cholesterol levels.
None of that is a surprise, of course. The interesting aspect of this study is its attempt to disentangle physical activity and sedentary time.
In comparison to the couch potatoes, both busy bees and sedentary exercisers had significantly lower BMI and HbA1c levels, and higher HDL-cholesterol levels.
Busy bees (but not sedentary exercisers) also had lower waist circumferences. Compared to couch potatoes, light movers had only one improvement: higher HDL-cholesterol levels.
What all this shows is not simply the importance of physical activity for health, but that physical activity offsets some of the evils of a high sedentary time. It also suggests that not being sedentary doesn't take you all that far — you still need to exercise.
Bakrania, K., Edwardson, C. L., Bodicoat, D. H., Esliger, D. W., Gill, J. M. R., Kazi, A., … Yates, T. (2016). Associations of mutually exclusive categories of physical activity and sedentary time with markers of cardiometabolic health in English adults: a cross-sectional analysis of the Health Survey for England. BMC Public Health, 16, 25. http://doi.org/10.1186/s12889-016-2694-9
A review of 200 studies on depression and inflammation has concluded that depression and inflammation fuel one another, with inflammation playing a key role in the development of depression in some people, and depression priming greater physiological responses to stress.
Moreover, depression that is caused by chronic inflammation is resistant to traditional therapy methods. However, it is more responsive to activities such as yoga, meditation, omega-3 fatty acids, NSAIDS and exercise.
The review indicates that treatment for depression needs to consider its pathway. The researcher suggests that chronic inflammation is most common in individuals who have experienced stress in their lives, including lower socio-economic status or those who experienced abuse or neglect as children. Other contributing factors are a high-fat diet and high body mass index.
If inflammation is a significant factor, it needs to be treated in tandem with the depression.
Kiecolt-Glaser, J. K., Derry, H. M., & Fagundes, C. P. (2015). Inflammation: Depression Fans the Flames and Feasts on the Heat. American Journal of Psychiatry, 172(11), 1075–1091. http://doi.org/10.1176/appi.ajp.2015.15020152
Stress, including sleep disturbance, is a major contributor to inflammation in the body. Insomnia is associated with increased risk for depression, medical comorbidities, and mortality.
A study involving 123 older adults (55+) with insomnia randomly assigned them to one of 3 types of classes: cognitive behavioral therapy for insomnia, tai chi, or a sleep seminar (the control condition).
Cognitive behavioral therapy for insomnia reduced insomnia symptoms and levels of the inflammation marker C-reactive protein, and reversed activation of molecular inflammatory signaling pathways. These benefits were maintained for 16 months.
Tai chi also reduced inflammation, reducing the expression of inflammation at the cellular level and reversing activation of inflammatory signaling pathways. It marginally reduced levels of C-reactive protein. Again, these benefits were maintained for 16 months.
Those participants assigned to the sleep seminar classes showed no significant changes in inflammatory markers, as expected.
Irwin, M. R., Olmstead, R., Breen, E. C., Witarama, T., Carrillo, C., Sadeghi, N., … Cole, S. (2015). Cognitive Behavioral Therapy and Tai Chi Reverse Cellular and Genomic Markers of Inflammation in Late-Life Insomnia: A Randomized Controlled Trial. Biological Psychiatry, 78(10), 721–729. http://doi.org/10.1016/j.biopsych.2015.01.010
Telomeres are the protective caps at the ends of chromosomes that affect how quickly cells age. With age, they shorten, and as their structural integrity weakens, the cells age and die quicker. Telomere length thus is a biomarker of cellular age. Stress is also thought to shorten telomere length.
A year-long study that looked at the effects of three healthy behaviors in 239 post-menopausal, non-smoking women has found that women who engaged in lower levels of healthy behaviors showed a significantly greater telomere shortening for every major life stressor that occurred. However, stress didn't lead to greater shortening in those women who maintained active lifestyles, healthy diets, and good quality sleep.
Shorter telomeres have become associated with a broad range of aging-related diseases, including stroke, vascular dementia, cardiovascular disease, obesity, osteoporosis diabetes, and many forms of cancer.
Puterman, E., Lin, J., Krauss, J., Blackburn, E. H., & Epel, E. S. (2015). Determinants of telomere attrition over 1 year in healthy older women: stress and health behaviors matter. Molecular Psychiatry, 20(4), 529–535. http://doi.org/10.1038/mp.2014.70
A review of trials of interventions that sought to reduce sitting time has found the following strategies, among others, were 'promising':
- having sit-stand desks at work
- keeping records of your sitting time
- setting individual goals for limiting sitting time
- having prompts and cues to remind you to stop sitting
- learning about the health benefits of reducing sitting time
- getting feedback on your behavior
- restructuring your physical and social environment to support the behavior changes
- practising the new behavior
- working out how to solve any problems that arise from shifting to less sitting time
- having social support.
The researchers did note that the overall standard of the studies was poor, so we can't yet point to any clear strategy, but these provide a guide for action. They also noted that the more promising interventions involved a greater number of strategies — in other words, to be successful, you need to tackle this behavior change from a number of angles.
Gardner, B., Smith, L., Lorencatto, F., Hamer, M., & Biddle, S. J. (2016). How to reduce sitting time? A review of behaviour change strategies used in sedentary behaviour reduction interventions among adults. Health Psychology Review, 10(1), 89–112. http://doi.org/10.1080/17437199.2015.1082146
A small study involving 11 non-obese, healthy men aged 20-35, has found that blood flow in leg arteries is significantly impaired after three hours of sitting, but not if they walk for five minutes every hour.
When people sit, slack muscles do not contract to effectively pump blood to the heart. Blood can pool in the legs and affect the endothelial function of arteries, or the ability of blood vessels to expand from increased blood flow. Impaired endothelial function is an early marker of cardiovascular disease.
In the study, participants sat for three hours without moving their legs, while the functionality of the femoral artery was taken at baseline and every hour. This showed that the expansion of the femoral artery as a result of increased blood flow was impaired by as much as 50% after just one hour.
In another session, they again sat for three hours, but also walked on a treadmill for 5 minutes at a speed of 2 mph at the 30-minute mark, 1.5-hour mark and 2.5-hour mark. In this case, arterial function stayed the same throughout the session.
Thosar, S. S., Bielko, S. L., Mather, K. J., Johnston, J. D., & Wallace, J. P. (2015). Effect of Prolonged Sitting and Breaks in Sitting Time on Endothelial Function: Medicine & Science in Sports & Exercise, 47(4), 843–849. http://doi.org/10.1249/MSS.0000000000000479
A Czech study involving 146 people with mild to moderate risk of cardiovascular disease has found that moderate wine drinking was only protective in people who exercised.
Participants were randomly assigned to one year of moderate consumption of red wine (Pinot Noir) or white wine (Chardonnay-Pinot) from the same year and wine region of the Czech Republic. They had to keep a logbook on their consumption of wine and other alcoholic beverages, medication use, and amount and type of exercise. They were required to return the corks from the wine bottles to confirm that they had drank the wine rather than sold it.
The study was looking for a rise in HDL cholesterol, indicating a protective effect against cardiovascular disease. However, there was no change in HDL cholesterol levels by the end of the study in either the red or white wine groups. Nor did it appreciably affect blood glucose, triglycerides, or levels of inflammatory markers like C-reactive protein, although LDL cholesterol was lower in both groups while total cholesterol was lower only in the red wine group.
However, those participants who engaged in regular exercise at least twice a week did show an increase in HDL cholesterol, as well as a decrease in LDL and total cholesterol. This occurred in both red and white wine groups.
Of course, the study didn't include a control group of people engaging in regular exercise who didn't drink, so all we can really say (and it's certainly worth saying) is that moderate wine drinking doesn't seem to help protect against cardiovascular disease, and that despite all the hype around red wine, with its greater antioxidants and resveratol, there's no evidence it's any healthier than white wine.
Taborsky M, Ostadal P, Petrek M. A pilot randomized trial comparing long-term effects of red and white wines on biomarkers of atherosclerosis (in vino veritas: IVV trial). Bratisl Lek Listy. 2012;113(3):156-158.
One big issue for which there is as yet no clear answer, is the question of whether it's the intensity or the amount of exercise which is more important.
One study involving 300 obese adults aimed to test this in a 6-month trial comparing those who maintained their usual activity level, those who did a low amount (around 30 minutes) of low-intensity exercise, those who did a high amount (around an hour) of low-intensity exercise, and those who did around 40 minutes of high-intensity exercise. All had five exercise sessions every week.
After 24 weeks of this, all the exercise groups showed smaller mean waist circumference and greater mean weight loss, compared to the control group, but there was no difference between the exercise groups in these measures. However, only the high-high group had lower 2-hour glucose levels than the controls, and only the two groups who did a higher amount of exercise had better insulin sensitivity.
Ross R et al. Effects of exercise amount and intensity on abdominal obesity and glucose tolerance in obese adults: A randomized trial. Ann Intern Med 2015 Mar 3; 162:325. (http://dx.doi.org/10.7326/M14-1189)
A study looking at the workout habits of more than 55,000 individuals for 15 years has concluded that running can reduce a person’s all-cause mortality rate by 30% and cardiovascular mortality rate by 45%. This equated to a difference of about three years of life.
But the really exciting news is that people who ran less than an hour each week showed the same mortality benefits compared to those who ran more than three hours in each week. Note that this is more about running, say, ten minutes every day, than only running once a week for a longer time! You don't have to run fast, either. Those running more slowly (< 6 miles/hour) got the same benefits.
Not running had about the same negative effect on life expectancy as having hypertension.
Around 24% of the participants did some running. The average age was 44.
Lee D, Pate RR, Lavie CJ, Sui X, Church TS, Blair SN. Leisure-Time Running Reduces All-Cause and Cardiovascular Mortality Risk. J Am Coll Cardiol. 2014;64(5):472-481. doi:10.1016/j.jacc.2014.04.058.
A Canadian study involving 129 sedentary adults (aged 18-64) found that they tended to underestimate how hard they should be working to achieve levels of moderate and vigorous intensity while moving on a treadmill. This is despite being given commonly used exercise intensity descriptors.
The finding suggests that, while considerable thought has been given in developing physical activity guidelines, most people don't understand them well enough to use them.
For adults to achieve a moderate intensity, their heart rates should be within the range of 64-76% of their maximum heart rate and between 77-83% for vigorous intensity, according to the Canadian and global physical activity guidelines.
Canning KL, Brown RE, Jamnik VK, Salmon A, Ardern CI, Kuk JL (2014) Individuals Underestimate Moderate and Vigorous Intensity Physical Activity. PLoS ONE 9(5): e97927. doi:10.1371/journal.pone.0097927
A small study involving 15 adults with moderate-to-severe obstructive sleep apnea and 19 controls with mild or no sleep apnea has found that predicted peak oxygen uptake (VO2), a measure of aerobic physical fitness, was significantly lower in those people with moderate to severe obstructive sleep apnea. Moreover, the number of times a person stopped breathing, for 10-seconds or more, per hour of sleep, predicted 16% of the variability observed in the group's peak VO2.
People who suffer from apnea are more likely to be obese and thus would be expected to be less fit as well, but even compared to people with similar BMI, the apnea patients had a reduced aerobic fitness. It's suggested that the sleep apnea itself causes structural changes in muscle that contributes to exercise problems.
VO2 max measurements may be an early marker for those who are at higher risk of stroke and heart attack
Beitler JR, Awad KM, Bakker JP, Edwards BA, DeYoung P, Djonlagic I, Forman DE, Quan SF, Malhotra A. Obstructive sleep apnea is associated with impaired exercise capacity: a cross-sectional study. J Clin Sleep Med 2014;10(11):1199-1204.
Your risk of developing type 2 diabetes is about three times greater if someone in your immediate family (parent, sibling) has it. In a study looking at the effects of exercise on this group, it was found that men who have a family member with type 2 diabetes had to expend more energy than a control group, to achieve the same benefits.
The study involved 35 unfit, slightly overweight but completely healthy men aged 30-45 who, for seven months, exercised regularly at a fitness centre. Half of them had relatives with type 2 diabetes, and half did not. (It's perhaps worth noting that 50 men began the study, but didn't continue — these were roughly evenly divided between the two groups.) Three hour-long exercise sessions were available each week, and participants went to 39 sessions on average (the range was large though: 11-107).
Those with family members with diabetes tended to go to the gym more often (group average was 59% more sessions), and this may be due to their increased motivation.
It must be emphasized that both groups lost weight, reduced their waist size, increased their fitness, and showed similar improvements in gene expressions. So exercise was a good idea for both groups. However, statistical analysis indicates that the at-risk group had to do more exercise than the control group to achieve the same benefit. The findings support earlier findings that those with close relatives with type 2 diabetes show smaller physiological changes to exercise, compared to those without such familial links.
Ekman, C., Elgzyri, T., Ström, K., Almgren, P., Parikh, H., Nitert, M. D., … Hansson, O. (2015). Less pronounced response to exercise in healthy relatives to type 2 diabetic subjects compared with controls. Journal of Applied Physiology, 119(9), 953–960. http://doi.org/10.1152/japplphysiol.01067.2014
In a study involving 52 sedentary, overweight, middle-aged men and women (aged 45-65), both exercise and calorie restriction had positive — and equal — effects on insulin sensitivity, but a combination of both had twice as much benefit for glucoregulation as either single approach. All three programs were designed to achieve about the same amount of weight loss (6-8%).
The study also indicated that both exercise and calorie restriction improve regulation of glucose levels through weight loss, but also through mechanisms that are independent of weight loss.
What all this suggests is that, even if you're maintaining a healthy weight, how much you eat, and whether you exercise, are factors that have health implications.
Weiss, E. P., Albert, S. G., Reeds, D. N., Kress, K. S., Ezekiel, U. R., McDaniel, J. L., … Villareal, D. T. (2015). Calorie Restriction and Matched Weight Loss From Exercise: Independent and Additive Effects on Glucoregulation and the Incretin System in Overweight Women and Men. Diabetes Care, 38(7), 1253–1262. http://doi.org/10.2337/dc14-2913
Mouse and human immune cells have demonstrated that a compound produced by the body when dieting or fasting (β-hydroxybutyrate — BHB) directly inhibits a protein, NLRP3, which is part of a complex set of proteins that drive the inflammatory response in several disorders, including autoimmune diseases, type 2 diabetes, Alzheimer's disease, atherosclerosis, and autoinflammatory disorders.
BHB is produced in response to fasting, high-intensity exercise, caloric restriction, or consumption of the low-carbohydrate ketogenic diet.
The finding helps explain why calorie restriction reduces inflammation.
Youm, Y.-H., Nguyen, K. Y., Grant, R. W., Goldberg, E. L., Bodogai, M., Kim, D., … Dixit, V. D. (2015). The ketone metabolite β-hydroxybutyrate blocks NLRP3 inflammasome-mediated inflammatory disease. Nature Medicine, 21(3), 263–269. http://doi.org/10.1038/nm.3804
A review of studies investigating lifestyle interventions that can delay or prevent the onset of type 2 diabetes in people with prediabetes and focusing specifically on ones that looked at gender differences, found that both men and women benefited equally from the interventions. The review of 12 studies found that those who received lifestyle interventions (including diet and exercise) were 40% less likely to progress to type 2 diabetes after 1 year, and 37% less likely to progress after 3 years.
People involved in lifestyle interventions also experienced greater weight reductions, and greater reductions of fasting plasma glucose.
Glechner, A., Harreiter, J., Gartlehner, G., Rohleder, S., Kautzky, A., Tuomilehto, J., … Kautzky-Willer, A. (2014). Sex-specific differences in diabetes prevention: a systematic review and meta-analysis. Diabetologia, 58(2), 242–254. http://doi.org/10.1007/s00125-014-3439-x
A Canadian study comparing neighborhoods that varied in “walkability” found that people living in neighborhoods with greater walkability had an average 13% lower likelihood of developing type 2 diabetes over 10 years, compared to those living in less walkable neighborhoods. However, walkability was only protective in those who were younger and middle aged; those who were age 65 or older saw no benefit from living in a walkable neighborhood.
Over the ten years of the study, the incidence of diabetes fell 7% in the most walkable neighborhoods, but rose 6% in the least walkable neighborhoods. Similarly, the incidence of excess weight (being overweight or obese) fell by 9% in the most walkable neighborhoods and rose 13% in the least walkable neighborhoods.
People who lived in the most walkable neighborhoods were three times more likely to walk or bicycle and half as likely to drive as a means of transportation.
The study was presented at the American Diabetes Association's 74th Scientific Session.
A ten-year study involving 4,207 older adults (73+) demonstrates that even in this older age group, modest physical activity was associated with a lower risk of cardiovascular disease. Among both men and women in good health:
- those who were more active had significantly lower risk of future heart attacks and stroke
- those who walked faster than three miles per hour had a 50% lower risk than those who walked at a pace of less than two mph (50%, 53%, 50% lower risk of coronary heart disease, stroke and total CVD, respectively)
- those who walked an average of seven blocks per day or more had a similar advantage compared to those who walked up to five blocks per week (36%, 54% and 47% lower risk of CHD, stroke and total CVD, respectively)
- those who engaged in leisure activities such as lawn-mowing, raking, gardening, swimming, biking and hiking, also had a lower risk of CHD, stroke and total CVD, compared to those who did not engage in leisure-time activities
Soares-Miranda, L., Siscovick, D. S., Psaty, B. M., Longstreth, W. T., & Mozaffarian, D. (2015). Physical Activity and Risk of Coronary Heart Disease and Stroke in Older Adults: The Cardiovascular Health Study. Circulation, CIRCULATIONAHA.115.018323. http://doi.org/10.1161/CIRCULATIONAHA.115.018323
A very large British study involving 1.1 million middle-aged women without prior vascular disease has found, over nine or so years, those who performed strenuous physical activity two to three times a week were about 20% less likely to develop heart disease, strokes or blood clots, compared to participants who reported little or no activity. However, those who reported doing strenuous activity daily had higher risk compared to those who only engaged in moderate amounts of activity.
Armstrong, M. E. G., Green, J., Reeves, G. K., Beral, V., & Cairns, B. J. (2015). Frequent Physical Activity May Not Reduce Vascular Disease Risk as Much as Moderate Activity Large Prospective Study of Women in the United Kingdom. Circulation, 131(8), 721–729. http://doi.org/10.1161/CIRCULATIONAHA.114.010296
Three recent studies point to the importance of cardiorespiratory fitness for older adults wanting to prevent cognitive decline.
Cardiorespiratory fitness improves executive function & episodic memory in older adults
A study comparing 33 young adults (age 18-31) and 27 older adults (age 55-82) has found that older adults with higher cardiorespiratory (i.e., fitness) levels performed as well as young adults on executive function tests. On long-term memory tests (a face–name memory task, and a visual episodic memory task), young adults performed better than older fit adults, who in turn performed better than less fit older adults.
Fitness had no effect on young adults' memory or executive functions (although bearing in mind other research, I'd suggest that this may be due to the cognitive testing being insufficiently demanding).
The finding confirms earlier research linking cardiorespiratory fitness with better executive function in older adults, and extends the association to episodic memory.
Regular exercise improves cerebral blood flow & short-term memory in older adults
A German study involving 40 healthy but initially sedentary older adults (aged 60-77) has found that those assigned to an exercise group (regular exercise on a treadmill for 3 months) improved not only their physical fitness but also their visual memory. This memory improvement was accompanied by increased blood flow and increased volume in the hippocampus. This improvement was seen in 7 of the 9 exercisers who were no older than 70. However, it tended not to be seen in those older than 70.
The control group (who also showed no such improvement) engaged in muscle relaxation sessions.
Increased brain perfusion as a result of physical exercise has previously been shown in younger people. This finding shows that some older adults may retain this ability, and also links this increase in blood flow to improvements in memory performance. It is less exciting to see that the effect was limited to visual short-term memory, but perhaps further exercise might have more far-reaching effects.
Cardiorespiratory fitness governs cerebrovascular health, not age
Another study has found that, among a group of older adults aged 55-85, blood flow in the gray matter was positively correlated with cardiorespiratory fitness and negatively correlated with age. That is, better cardiorespiratory fitness was linked to better blood flow in the brain, and both tended to decline with increasing age. Moreover, blood flow in the gray matter was entirely governed by cardiorespiratory fitness.
In other words, cerebrovascular health is largely a matter of your cardiorespiratory fitness, not your age.
Several recent studies add to the evidence that physical fitness boosts cognitive processing in children.
Physically fit kids have better white matter
A brain imaging study involving 24 9- and 10-year-olds has found that physical fitness was associated with significant differences in the integrity of several white-matter tracts in the brain: the corpus callosum, the superior longitudinal fasciculus, and the superior corona radiata. All of these are involved in learning and memory. The differences are associated with faster and more efficient nerve activity.
The findings build on previous research linking higher levels of aerobic fitness with greater volumes of gray matter (i.e., more neurons) in regions important for memory and learning, and suggest that better communication along the white-matter tracts might be another mechanism explaining why aerobic fitness is associated with improved cognition.
Factors such as socio-economic status, the timing of puberty, IQ, or a diagnosis of ADHD or other learning disabilities, were taken into account in the analysis.
Physical fitness linked to better reading skills in children
A study looking at brain activity during reading has found that physically fit children have faster and more robust brain responses during reading than their less-fit peers. These differences correspond with better language skills.
Brainwave patterns called "event-related potentials" (ERPs) vary by person, stimulus and task. A brainwave component called N400 is stronger when a sentence doesn't make sense compared to a meaningful sentence, for example. The component P600 is associated with grammatical rules.
The study found that children who were more fit (as measured by oxygen uptake during exercise) had higher amplitude N400 and P600 waves than their less-fit peers when reading normal or nonsensical sentences. The N400 also had shorter latency in children who were more fit, suggesting that they processed the same information more quickly. These differences corresponded to better reading performance and language comprehension.
Such findings suggest that higher fitness may be associated with a richer network of words and their meanings, and a greater ability to detect and/or repair syntactic errors.
Large study links physical fitness to school grades
A large Spanish study involving 2,038 young people (6-18; average age 10) has found that physical fitness was associated with better academic performance.
Fitness was measured in terms of cardiorespiratory capacity, motor ability and muscle strength. Cardiorespiratory capacity and motor ability were independently associated with all measures of academic performance (math grade, language grade, average of math and language grades, and overall grade point average), even after adjusting for fitness and fatness. Muscle strength was not associated with academic performance independent of cardiorespiratory capacity and motor ability.
Aerobic fitness boosts learning in school children
A study involving 48 9- and 10-year-olds has found that those with higher levels of physical fitness performed significantly better at a memorization task. The task involved memorizing names and locations on a fictitious map, either by study only or by being tested on the material as they studied. They were then tested a day later, under conditions of free recall and cued recall. Half the children were in the top 30% of their age group on a test measuring aerobic fitness, while the other half scored in the lowest 30%.
While there was no difference between the high-fitness and low-fitness groups at the initial learning session, and no difference on the delayed test when learning had involved study plus testing, the high-fitness group scored considerably better than the low-fitness group when learning involved study only (an average of 43% correct vs 25.8%).
This suggests that the benefits of fitness are greatest when initial learning is most challenging (as discussed at length by me in my book on practice, and in other articles, retrieval practice as a part of study improves learning significantly).
Childhood obesity linked to poorer cognitive control
A study involving 74 preadolescent children, of whom half were obese and half at a healthy weight, has found that the obese children were considerably slower at a task in which they were shown three fish facing either left or right and had to press a button based on the direction of the middle fish.
The healthy-weight children also improved their performance more after making an error, and their brain activity showed a larger response when they made an error. This difference was even greater in more demanding situations (the flanking fish could either point in the same direction or in the opposite direction). This suggests that childhood obesity is associated with poorer action monitoring, a vital aspect of cognitive control.
There are two particularly interesting findings from this collection of studies:
- the idea that physical fitness helps cognition through multiple effects, such as increasing gray matter volume, improving white matter integrity, and strengthening brainwave patterns
- the idea that the effects of fitness may not be revealed in less-demanding situations.
A study involving 97 healthy older adults (65-89) has found that those with the “Alzheimer’s gene” (APOe4) who didn’t engage in much physical activity showed a decrease in hippocampal volume (3%) over 18 months. Those with the gene who did exercise showed no change in the size of their hippocampus, nor did those without the gene, regardless of exercise. Physical activity was classified as low if the participant reported two or fewer days per week of low intensity activity, such as no activity, slow walking or light chores. Physical activity was classified as high if the participant reported three or more days/week of moderate to vigorous activity
The finding suggests that those with the risky gene will benefit most from regular exercise — indeed, this is as yet the only known means to counteract hippocampal shrinkage.
Data from a survey of 20,000 people across the UK has found that people who cycle, walk, or take public transport to work had a lower risk of being overweight than those who drove or took a taxi. People who walked to work were 40% less likely to have diabetes than those who drove and 17% less likely to have high blood pressure. Cyclists were around half as likely to have diabetes as drivers.
A Swedish study of some 4,000 60-year-olds has found that regular “non-exercise” physical activity such as gardening or DIY significantly reduced risk of heart attack or stroke, with those who were most active on a daily basis having a 27% lower risk of a heart attack or stroke and a 30% reduced risk of death from all causes. This was so regardless of how much regular formal exercise was taken. Regular physical activity was also associated with better waist circumference, high-density lipoprotein cholesterol and triglycerides in both sexes and with lower insulin, glucose and fibrinogen levels in men. Metabolic syndrome was also significantly less likely.
An 11-week trial involving 54 young, healthy men and women engaging in an endurance training program, has found that markers for the production of new muscle mitochondria only increased in the group not taking vitamin C and E supplements. It’s possible that high doses of vitamins C and E act as antioxidants and take away some of the oxidative stress needed to develop muscular endurance.
A mouse study has found that long-term physical activity increased levels of two proteins in the mitochondria of their heart. It’s thought this might help explain why regular exercise improves cardiovascular health.
Data from 133,479 women in the California Teachers Study has found that those who reported doing moderate physical activity (such as brisk walking) in the three years before enrolling in the study were 20% less likely to suffer a stroke than women who reported no activity. More strenuous activity didn’t further reduce risk.
Postmenopausal women taking menopausal hormone therapy had more than a 30% higher risk of stroke than women who never used menopausal hormone therapy, but this risk started diminishing after they stopped taking hormones. Moderate exercise helped offset the increased stroke risk.
It’s well established that performing both cardio- and resistance training in the same session is decidedly better than doing them separately, but does the order matter?
A study involving men aged 18-40, who performed either supervised cardio- immediately followed by strength training, or vice versa, for 24 weeks (2-3 combined cardio- and resistance sessions per week), has found that over the 6 months, the order didn’t matter. However, the group starting with cardio did show slower recovery in the beginning.
A year-long study involving 424 sedentary, mobility-limited seniors aged 70-89, has found that variants in a specific gene (the ACE I/D gene) affect seniors’ ability to benefit from exercise. Physical activity intervention led to greater improvements in walking speed among ID and DD genotype carriers (29.9% and 13.7% respectively), but among II genotype carriers, health education alone led to more improvements in walking speed than physical activity intervention (20% vs. 18.5%).
Data from the American National Health and Nutrition Examination Survey (NHANES) III, involving 3,659 individuals (men aged 55+; women 65+), has found that the more muscle mass older adults have, the less likely they are to die prematurely. The findings add to the growing evidence that overall body composition — and not the widely used body mass index (BMI) — is a better predictor of mortality.
Brain scans have revealed that those who regularly practiced yoga had larger brain volume in the somatosensory cortex (maps the body), superior parietal cortex (involved in directing attention), visual cortex (perhaps because of visualization techniques), hippocampus, precuneus and the posterior cingulate cortex (the last two involved in our concept of self).
A year-long study involving young adults has compared those who engaged in either tai chi or brisk walking or no exercise. Those who practiced tai chi had a significantly higher number of CD 34+ cells compared with those in the other groups. CD 34+ cells are markers for blood stem cells involved in cell self-renewal, differentiation and proliferation. The findings suggest tai chi may prompt vasodilation and increase blood flow.
Mice given decaffeinated green tea and regular exercise lost weight and improved their health after 16 weeks. Specifically, they reduced body mass by 27% (on average), reduced abdominal fat by 37%; reduced blood glucose level by 17%, plasma insulin level by 65%, and insulin resistance by 65%..
Neither green tea alone, nor exercise alone, produced such significant changes. The amount of green tea was a lot: the equivalent of 8-10 cups a day. Decaffeination may not be important; it was done to keep the effects of caffeine out of the study.
Green tea is thought to affect genes related to energy metabolism.
A mouse study has found that obese mice had high levels of interleukin 1 in both their blood and their brains, and this was associated with:
- high levels of inflammation,
- low levels of a biochemical important to synapse function, and
- impaired cognitive function.
Moreover, when fat was removed from the obese mice, interleukin levels dropped dramatically, and cognitive performance improved.
Putting obese mice on an exercise program had a similar effect, even though they didn’t lose weight — but they gained muscle and lost fat.
As many of you will know, I like nature-improves-mind stories. A new twist comes from a small Scottish study, in which participants were fitted up with a mobile EEG monitor that enabled their brainwaves to be recorded as they walked for 25 minutes through one of three different urban settings: an urban shopping street, a path through green space, or a street in a busy commercial district. The monitors measured five ‘channels’ that are claimed to reflect “short-term excitement,” “frustration,” “engagement,” “arousal,” and “meditation level."
Consistent with Attention restoration theory, walkers entering the green zone showed lower frustration, engagement and arousal, and higher meditation, and then showed higher engagement when moving out of it — suggesting that their time in a natural environment had ‘refreshed’ their brain.
Data from the very large, long-running UK National Child Development Study has revealed that those who exercised at least four times weekly as both a child and an adult performed better on cognitive tests at age 50 than those who exercised two to three times per month or less, and the latter in turn performed better than those who hadn’t regularly exercised at all.
The data was collected through face-to-face interviews of more than 9,000 people at the ages of 11, 16, 33, 42, 46, and 50. Cognitive score was based on an immediate and delayed recall task (ten unrelated words), ability to name as many animals as possible in one minute, and time taken to cross out specified letters in a series.
The findings add a further perspective to the pile of evidence for the value of regular exercise in fighting age-related cognitive decline.