Exercise and Depression in the General Population Flashcards
cross-section studies
- > cross-sectional (observational) study compares different population groups at a single point in time
- > yoshiuchi et al., 2006 showed that daily step count and daily duration of moderate intensity PA were significantly and inversely correlated with depression
- > physical activity goes up, depression symptoms go down
longitudinal studies
- > longitudinal study researchers conduct several observations of the same subjects over a period of time
- > paffenbarger et al. (1994)
- > participants were split into 1 of 3 weekly energy expenditure (EE) categories, <1000, 1000-2499, 25000+ kcal/week
- > those with the highest weekly EE were 28% less likely to develop depression than the lowest weekly EE group
- > those with moderate weekly EE were 17% less likely to develop depression than the lowest weekly EE group
effects of exercise training on older patients with major depression (blumenthal et al.)
background: exercise training may reduce depressive symptoms in older patients with major depressive disorder (MDD)
objective: to asses the effectiveness of an aerobic exercise program compared to standard medication (antidepressants)
methods: 156 men & women with MDD randomly assigned to exercise, antidepressant medication or combined exercise and medication
treatment period: 16 weeks
primary outcome: better scores of Hamliton Depression Scale and Beck Depression Inventory
secondary outcome: aerobic capacity, life satisfaction, self-esteem, anxiety and dysfunctional cognitions
conclusion of exercise training and major depressive disorder
- > an exercise training program may be considered an alternative to antidepressants for treatment of depression in older persons
- > after 16 weeks of treatment, exercise was equally effective in reducing depression among patients with MDD
statistically significant change
=> usually focus on statistical significance to discuss effectiveness of an intervention, meaning the change is likely not by chance. however, this does not necessarily mean that it is clinically important
=> Centre for Epidemiological Studies - Depression (CES-D)
= or > means at risk for depression
=> statistical significance would be comparing the mean of two groups and seeing if there is a difference
=> this does not mean their score improved clinically
prenatal depression
- > affects up to 20% of all pregnancies
- > 19% will continue to have depressive symptoms postpartum
- > can negatively impact growing fetus: preterm birth, intrauterine growth restriction, early cessation of breastfeeding
prenatal depression treatment options
=> pharmacological treatment options are often avoided
=> most women go untreated
=> recent literature has shown that exercise may prevent prenatal depression
clinically reliable change criteria
reliability: if measures were repeated in the same population you would see the same results
clinically important: practical importance of the treatment effect being observed
purpose and method of physical activity and prenatal depression study
purpose: to determine if prenatal exercise during pregnancy can treat depression among women who enter pregnancy at risk for depression and if exercise can have a clinically reliable change on depression risk during pregnancy
method: randomized controlled trial: exercise group and standard care control group
group fitness class 3 / per week
aerobic training and resistance exercises
baseline: 9-12 weeks
completion 36-38 weeks
at baseline and at the end, completed the CES-D
calculating the clinically reliable change criteria
- the reliability of the measurement (Cronbach’s alpha) (0.752)
- standard deviation for the current population
- standard error of difference between scores at 2 time points (3.6)
- gives clinically reliable change criteria (7.09 -> 7 - how many of the treatment patients reduced the depression symptom on the CES-D by atleast 7 points)
results of exercise and prenatal depression study
- 61 women included (36 exercise, 25 control)
- assessed potential confounding variables: age, pre-pregnancy BMI, smoking status, education level, occupation, previous miscarriage incidence, parity, weight gain
- no difference observed from intervention and control groups
- >7 point decrease in CES-D scores and below 16, control reduced score by 3 points
- 22 women (61%) had a score decrease by 7 points in the EG compared to 8 women (32%) had a score decrease by 7 points in the CG (chi square p<0.05)
findings on prenatal exercise and depression
- prenatal exercise may have both a statistical and clinically reliable treatment effect on depression risk
- prenatal exercise may be prescribed to treat women who enter pregnancy with depression risk
- exercise can increase the likelihood of achieving the clinically reliable threshold
strengths and limitations of prenatal exercise and depression
strengths
- first study to calculate and apply clinically reliable change criteria for this population; calculation can be used for other outcomes
- only included women with a CES-D score greater or equal to 16
limitations
- convenience sample used
- group dynamics not assessed
future steps for prenatal exercise and depression studies
- design a prenatal exercise intervention based study with an priori sample size calculation specifically for women at risk for prenatal depression
- follow up in the postpartum period
by providing clinical evidence for prenatal exercise and depression
- inclusion of prenatal care
- treatment option
- support women and the next generation in leading a healthy lifestyle
review of exercise for depression (cooney et al.)
- found mean difference of -0.62 favoring exercise
- concluded that the antidepressant effect of exercise may be small
stepwise reduction effect over time
- pooled standardize mean difference (SMD) from:
- 1.10 in 2001
- 0.82 in 2009
- 0.67 in 2012
- 0.62 in 2013
- hence an effect of 0.6 suggests that the experiemental group has a net gain of 23% over the control group
- the score of the average person in the experimental group exceeds the scores of 73% of the control group
demystifying the shrinkage phenomenon
- applying the following rule to the data: only examine studies where exercise is compared to a passive (non-exercise) control
- pool SMD is raised from -0.62 to -0.90
how does exercise affect coping efficacy in those with depression?
- depression is associated with low efficacious beliefs like, low confidence in ability to achieve outcomes, regulate negative cognition, cope
- exercise leads to improved coping efficacy in those with depression
how does chronically high levels of cortisol relate to episodic memory deficits and reduced hippocampal volume?
- depression is often associated with episodic memory impairment, reduced hippocampal volume, high or dyregulated cortisol secretion
- episodic memory processing occurs in the hippocampus and surrounding areas
- chronically high levels of cortisol independently implicated in both episodic memory deficits and reduced hippocampal volume
how does exercise affect episodic memory?
- in those with depression memory function improves with successful treatment
- since exercise is a efficacious treatment, exercise has been shown to improve episodic memory in healthy young adults
how does exercise affect cortisol secretion?
- in those with depression cortisol secretion is normalized with successful treatment
- since exercise is an efficacious treatment, exercise does decrease cortisol secretion in healthy adults
how does exercise affect episodic memory and hippocampal volume?
- the effect of exercise on episodic memory and hippocampal volume may be mediated through cortisol
examination for exercise as a treatment for depression
procedure: participants who met criteria were randomized into a 12 week aerobic exercise or stretching intervention
participants attend sessions 3x per week for 30-40 mins
aerobic exercise group = moderate intensity, at 40-70% of Heart Rate Reserve
stretching group = mild-intensity stretching
measures:
depression - Beck Depression Inventory (BDI-II) and The Montgomery-Asberg Depression Rating Scale (MADRAS)
coping efficacy - depression coping self-efficacy scale
episodic memory - verbal recall task - uncued and cued recall
cortisol - salivary cortisol concentration at waking, 30 min post waking & before bed
cardiovascular fitness - modified Astrand-Ryhming cycle ergometer test
flexibility - YMCA Sit-and-Reach test
attendance
results of BDI-ll after exercise treatments
Beck Depression Inventory: decreased in both groups at 6 and 12 weeks
decreased more in the aerobic exercise group
results of MADRAS after exercise treatment
The Montgomery-Åsberg Depression Rating Scale: decreased in both groups at 12 weeks
decreased more in the aerobic exercise group
results of coping efficacy after exercise treatment
Depression Coping Self-Efficacy Scale: increased in both groups at 6 and 12 weeks
coping efficacy improved more in the stretching group
results of un-cued recall after exercise treatment
Un-cued recall: improved in both groups at 6 and 12 weeks
improved more in the aerobic exercise group
results of cued recall after exercise treatment
cued recall: improved in both groups at 6 weeks and leveled at 12 weeks
cued recall improved more in the aerobic exercise group
results of CAR after exercise treatment
cortisol awakening response: decreased in both groups at 6 weeks
decreased in aerobic exercise group
increased in stretching group at 12 weeks
no significant time effect
significant time*group effect (p=0.042)
clinical significance of exercise treatment for depression
- recent research on the BDI has shown clinical significance
- clinically important reduction in symptoms:
- > cut-off score of 14.29 must be crossed in order to move from being depressed to being non-depressed
- > change in score greater than the reliable change index (RCI) of 8.46 must be observed
- both exercise and stretching groups passed the cut-off
- only exercise group had a change score greater than the RCI (10.6 vs 6.4)
conclusion of exercise treatment for depression
- participants in the aerobic exercise group showed significant reductions in depression and significant improvements in coping efficacy and episodic memory
- however, these benefits also occured albeit to a lesser extent in the stretching group
- study was insufficiently powered to detect statistically signifcant small to medium effects that favored the exercise condition
- adherence was a problem in stretching group
- exercise group satisfied both criteria for a clinically important change in depression
- both aerobic exercise and stretching seem to be good treatments for depressions with positive changes to coping efficacy and episodic memory
however, stress (cortisol) was only positively influenced by aerobic exercise
kynurenine (KYN)
- kynurenine produced mainly in the liver in response to stress that travels to the brain, where it’s linked to neuroinflammation, cell death and depression
- exercise causes your muscles to increase levels of a protein called PGC-1alpha1, which in turn leads to a higher level of an enzyme (KAT) that converts kynurenine into kynurenic acid (KYNA) which can’t cross into the blood-brain barrier, so unlike kynurenine it can’t get into the brain and damage it
is exercise effective as pharmacological products in reducing depression?
- exercise is just as effective as pharmacological products in reducing depression
- implications: free and offeres other health benefits (fitness)
