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21st April 2022
The risk of depression can be greatly reduced even by undertaking lower amounts of the recommended levels of physical activity according to the results of a meta-analysis by researchers from the MRC Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge, UK.
Depression is a common, global mental disorder that is believed to affect 5% of the population. Moreover, a 2015 meta-analysis estimated that every year, 14.3% of global deaths, approximately 8 million deaths, can be linked to mental disorders. With such a high prevalence and associated mortality, much needs to be done to try and prevent or reduce depression risk. One possible mitigating factor is physical activity and according to one systematic review, promoting physical activity may serve as a valuable mental health promotion strategy in reducing the risk of developing depression. In fact, a 2018 meta-analysis of prospective cohort studies suggested that the available evidence supports the idea that physical activity can confer protection against the emergence of depression regardless of age and geographical region. With a good deal of evidence indicating a protective effect from physical activity, what remains uncertain is the strength or shape of the association between physical activity and depression.
For the present analysis, the UK team looked for trials that included any dimension of physical activity at three or more exposure levels, with at least 3,000 participants and with a follow-up period of not less than 3 years. Levels of physical activity were measured as marginal metabolic equivalents task hours per week (mMet-h/wk), where 1 Met represented the resting metabolic rate and 8.8 mMet-h/week was equivalent to the recommended weekly amount of physical activity. The outcome of interest was depression, major depressive disorder and elevated depression symptoms.
Depression risk and physical activity levels
The literature review identified 15 eligible publications including 191,130 participants (64% women) contributing 28,806 incident depression events and 2,110,588 person-years.
The results suggested an inverse and curvilinear dose-response between physical activity and depression, such that relative to adults who did not report undertaking any physical activity, those doing at least half of the recommended activity (4.4 mMet-hrs/week), had an 18% lower risk of depression (relative risk, RR = 0.82, 95% CI 0.77 – 0.87). Among those achieving the recommended amounts of activity (8.8 mMet-hrs/week), there was a 25% reduced risk of depression (RR = 0.75, 95% CI 0.68 – 0.82) and this reduction was the same for major depression and slightly lower for elevated depressive symptoms (RR = 0.73). However, interestingly, there was little apparent benefit derived from increasing activity to 17.5 mMet-hrs/week (RR = 0.72, 95% CI 0.64 – 0.81), for each of the three outcome measures.
Using potential impact fraction (PIF) analysis, the authors calculated that around 11.5% of incident depression could have been prevented in adults who achieved at least 8.8 mMet-hrs/week of physical activity.
Translating their findings into practical advice, the authors stated that accumulating an activity equivalent to 2.5 hours/week of brisk walking was associated with a 25% lower risk of depression and that achieving half of this level, reduced the risk by 18% compared with those who undertook no physical activity.
They concluded that substantial mental health benefits accrue from the achievement of physical activity levels even below those currently recommended.
Pearce M et al. Association Between Physical Activity and Risk of Depression: A Systematic Review and Meta-analysis JAMA Psychiatry 2022
28th March 2022
Increased physical activity levels in older adults with high serum levels of neurofilament light chain (NFL) leads to a reduction in the rate of cognitive decline. This was the conclusion of a study by researchers from the Rush Institute for Healthy Aging, Rush University Medical Center, Chicago, US.
Neurofilament light chain is a neuronal cytoplasmic protein expressed in large calibre myelinated axons. Furthermore, in both central nervous system and peripheral nervous system diseases associated with axonal injury or degeneration, the concentration of NFL has been found to increase in both cerebrospinal fluid (CSF) and blood. In addition, levels of CSF NFL are associated with cognitive impairments in patients with Alzheimer disease and fronto-temporal dementia. As a result, it has been suggested that NFL could be used to predict the development of sporadic Alzheimer’s disease and cognitive decline. One factor which appears to be associated with a reduced cognitive decline is physical activity and in a 2011 meta-analysis, the authors concluded that there was a significant and consistent protection for all levels of physical activity against the occurrence of cognitive decline.
For the present study, the US team wanted to examine whether among individuals with high NFL concentrations, increased physical activity was associated with a slowed rate of cognitive decline over time. They turned to the Chicago Health and Aging Project (CHAP), which is a longitudinal population study of common chronic health problems of older persons and in particular, risk factors for incident Alzheimer’s disease. Blood samples were taken and the concentration of NFL measured at baseline and during each follow-up appointment and dichotomised as low (< 25.5 pg./ml) or high (> 25 pg./ml). Levels of physical activity were self-reported divided into three groups: little activity, medium and high, in which the latter group reported physical activity levels > 150 minutes/week. A number of cognitive tests were used to assess global cognitive function. The main outcome measure was the association of baseline activity and NFL concentrations with changes in global cognitive function over time.
Increased physical activity and NFL in relation to cognitive decline
A total of 1158 participants with a mean age of 77.4 years (63% female) were included in the study. The mean level of physical activity per week was 170.78 minutes and the geometric mean NFL concentration was 26.1 pg/ml.
Among those with a high NFL levels, indicating more axonal injury, individuals engaging in medium physical activity (< 150 minutes/week), had a 12% slower rate of global cognitive decline compared to those in the low physical activity group. Similarly, those with increased physical activity (i.e., the high group), had a 36% slower rate of decline in comparison to the low physical activity group.
Interestingly, the the rates of cognitive decline were also higher among those with lower levels of NFL, i.e., with less neural damage. For example, in comparison to the group who undertook little or no physical activity, those who undertook medium physical activity had a 43% slower decline and the high activity group, at 30% slower decline.
The authors concluded that among older adults with high levels of serum NFL, increased physical activity levels were associated with a slower rate of cognitive decline. They added that future studies should examine the relationship between cognitive decline and different forms of exercise such as aerobics and strength training.
Desai P et al. Examination of Neurofilament Light Chain Serum Concentrations, Physical Activity, and Cognitive Decline in Older Adults JAMA Netw Open 2022
22nd February 2022
Undertaking physical activity for a minimum of 20 minutes every day is associated with a significant reduction in the risk of cardiovascular disease in elderly patients, according to the results of a longitudinal study by a team of researchers from the department of Cardio-thoraco-Vascular Sciences and Public Health, University of Padua, Italy.
There is already good evidence demonstrating that higher recreational and non-recreational physical activity is associated with a lower risk of mortality and CVD events. In addition, the risk of cardiovascular disease has been found to reduce in a linear manner with increasing levels of physical activity up to around 41%. However, whilst there are clear health benefits derived from engaging in greater levels of physical activity, few of the reviewed studies focused on older (≥65 years) adults. Furthermore, there is little evidence on the association of activity trajectories and specific cardiovascular outcomes, though where this has been examined, the authors concluded that cardiovascular health trajectories may be associated with subsequent CVD risk.
With an increasingly ageing population, for the present study, the Italian team sought to explore the relationship between different trajectories of activity and cardiovascular events in older men and women. The team turned to the Progetto Veneto Anziani study which has followed over 3,000 Italians aged 65 years and older from 1995 and who had follow-up visits after 4 and 7 years. Individuals underwent physical examinations and completed various medical questionnaires, assessing smoking status, alcohol use, co-morbidities etc and morbidity and mortality data collection was extended until 2018. The levels of physical activity were collected at baseline and at follow-up appointments and individuals were subsequently categorised as active if they engaged in > 20 minutes of activity each day or inactive if < 20 minutes each day. Based on information collected from participants, the researchers defined four separate exercise trajectories: stable-low (i.e., essentially inactive); high-decreasing (active – inactive); low-increasing (inactive-active) and finally stable-high (maintaining activity). Outcomes of interest were a diagnosis of cardiovascular disease (CVD), coronary heart disease (CHD), heart failure (HF) and stroke.
Physical activity and cardiovascular outcomes
A total of 2754 individuals with a mean age of 75.1 years (60.2% female) were included and followed-up for a period of 20 years. During the 20-year follow-up, there were 1037 incident cardiovascular events.
The rates of incident coronary heart disease and heart failure were significantly associated with being active compared to inactive. For example, there was a lower risk of CVD (hazard ratio, HR = 0.74, 95% CI 0.58 – 0.94), CHD (HR = 0.66, 95% CI 0.50 – 0.87) and HF (HR = 0.72, 95% CI 0.53 – 0.98) in men but not for strokes. In contrast, none of these relationships were significant for women. However, physical activity was associated with a significantly reduced risk of overall mortality in both men (HR = 0.72, 95% CI 0.62 – 0.84) and women (HR = 0.81, 95% CI 0.72 – 0.92).
Considering the dose-response relationship, the risk reduction for any incident cardiovascular event was associated with doing at least 20 minutes of activity each day for those aged 70. Using trajectories of physical activity and using the stable-low category as the reference point, for any cardiovascular disease, the fully adjusted hazard ratio was 0.48 (95% CI 0.27 – 0.86) for men in the stable-high category, i.e., a 52% reduced risk of CVD in those who maintained high levels of activity in later life. Nevertheless, this association was not significant for women.
The authors concluded that greater amounts of physical activity in older adults was associated with a reduced risk of CHD and heart failure and that a minimum of 20 minutes each day of moderate to vigorous activity should be recommended for the greatest cardiovascular benefits.
Amidei CB et al. Association of physical activity trajectories with major cardiovascular diseases in elderly people Heart 2022
30th November 2020
It has been suggested that undertaking vigorous physical activity (VPA) might offer additional health benefits compared with MPA alone. However, what remains unclear is the amount of VPA which needs to be incorporated into any form of MPA to derive a mortality benefit. In this study, a team from the department of epidemiology and biostatistics, Wuhan, China, set out to retrospectively analysis data acquired from a national health interview survey (NHIS) conducted between 1997-2013, which included data on self-reported levels of physical activity and was linked to the national death index records through to the end of December 2015. The NHIS survey included questions looking at how frequently individuals undertook MPA, how long it lasted and whether this activity included any VPA that caused heavy sweating or a large increase in heart rate. The researchers calculated the amount of MPA undertaken and the proportion of VPA as a percentage of the total MPA. The outcomes of interest were mortality and divided into: all-cause mortality; cardiovascular disease and cancer mortality.
The sample included data on 403,681 individuals (51.7% female) with an average age of 42.8 years who were followed for a median of 10.1 years and over which time there were 36,861 deaths. The amount of VPA undertaken varied and just over a fifth (21.3%) of participants reported that VPA accounted for between 50 and 75% of their total physical activity. When compared to individuals performing no VPA, where VPA represented between 50 and 75% of all physical activity, there was a 17% reduction in all-cause mortality (hazard ratio, HR = 0.83, 95% CI 0.79-0.91, p < 0.001). Furthermore, there was also a significant reduction in the risk of cardiovascular (HR = 0.83) and cancer (HR = 0.80) mortality. Further increases in VPA did not lead to a greater reduction in either all-cause, cardiovascular or cancer mortality. With respect to duration, the results suggested that performing 150 to 299 minutes of MPA and 150 minutes or more of VPA had the lowest all-cause mortality risk. Commenting on these results, the authors suggested that public health message should be that individuals need to perform at least 150 minutes per week of MPA and that increasing the amount of VPA within this regime, leads to greater mortality benefits.
Citation Wang Yet al. Association of physical activity intensity with mortality.. A national cohort study of 402,681 US adults. JAMA Intern Med 2020 doi:10.1001/jamainternmed.2020.6331