Major Depressive Disorder (MDD) is a significant health problem, which is expected to rank second only to coronary heart disease as a major disease worldwide by the end of the year 2010 (Lawlor and Hopker, 2001; Blumenthal et al. , 2007). This report shall examine and summarise four research articles which have studied the relationship between exercise and depression: their rationale, their methods and findings.
It shall show that based on the findings of these four studies, there appears to be strong evidence that exercise is useful as an adjunct to traditional methods of anti-depression therapy. It then concludes with a discussion on depression as a worldwide problem, the problems with the research articles examined, and then end with a look at the associated research possibilities and suggestions for further research. Article Summaries Veale, D. , Le Fevre, K. , Pantelis, C.
, de Souza, V. , Mann, A. and Sargent, A. (1992) ‘Aerobic Exercise in the Adjunctive treatment of Depression: A Randomised Controlled Trial’ Rationale of the Study The researchers aimed to add to and improve on the existing body of knowledge by using larger sample populations and standardised assessment methods to confirm the beneficial effects of exercise on depression as well as to assess if these effects were due to the consequent improvement in aerobic fitness. Methods
Participants – With the use of the Clinical Interview Schedule (CIS) and the selection of participants with total scores of 17 or more, a depression score of 2 or more and aged between 18 and 60 years, a total of 124 study subjects were chosen over a period of 2 years. Experimental Design – The study was carried out through the a set of two randomised controlled studies carried out 12 weeks apart where outcomes were compared with the baseline data. In the first study, a total of 48 participants were placed in a group that were to undergo regular aerobic exercise (supervised three times a week) while a control group of 35 did not.
In the second study which was commenced immediately after the completion of the first, there were 63 members of the aerobic group and another 26 who were subjected to regular supervised low-intensity exercise (consisting of stretching, relaxation and yoga) three times a week. Outcome Variables – Comparisons were made between baseline and post study scores on the Clinical Interview Schedule (CIS), the Social Supports and Stresses Interview, the Beck Depression Inventory and the State-Trait Anxiety Inventory as well as levels of aerobic fitness.
Results The results of the first study suggested that exercise can be used successfully as an addition to other forms of treatments for depression. It was however identified by the second study that it was not the improvement in aerobic fitness that was responsible for the therapeutic effect of exercise. Blumenthal, J. A. , Babyak, M. A. , Doraiswamy, M. , Watkins, L. , Hoffman, B. M. , Barbour, K. A. , Herman, S. , Craighead, E. , Brosse, A. , Waugh, R. , Hinderliter, A. amd Sherwood, A.
(2007) ‘Exercise and Pharmacotherapy in the treatment of Major Depressive Disorder’ Rationale of the Study In view of the methodological limitations of prior exercise studies (including some carried out by the same study group), the authors sought to design a study that could control any factors which could raise a doubt about the effectiveness of exercise in the management of clinical depression. Methods Participants – Patients were chosen by screening out-patients who presented at the Duke University Medical Centre in response to adverts in the media.
Candidates with scores of ? 12 on the Beck Depression Inventory II (BDI), aged 40 years or above and living a sedentary lifestyle who were not undergoing any form of psychiatric treatment were selected. Further assessment of candidate suitability involved a medical screening process, a depression assessment using the structured clinical interview to diagnose depression and the Hamilton Depression Rating Scale (HAM-D) to assess its severity as well as exercise testing to determine patient fitness levels.
Experimental Design – With computer generated random selections, participants were assigned into four groups: one group of 51 participants undergoing supervised aerobic exercises, another 53 undergoing home-based aerobic exercise, 49 taking the antidepressant Sertraline and another 49 taking a placebo drug During the test period which lasted 16 weeks, the first group underwent regular thrice weekly supervised exercise while the second carried out the same schedule with minimal supervision in their homes.
Another group took an antidepressant once daily while the last group took a placebo once daily. Outcome Variables – The study compared baseline scores at the NAM-D with post-study scores. Participants with scores of ? 8 were taken as being in remission. Results It was observed that both home-based and supervised exercise and anti-depressant medication achieved higher remission levels than placebo. Supervised exercise led to 45% remission rates, home-based exercise 40 %, medication 47 % and placebo 31 %. Dimeo, F. , Bauer, M. , Varahram, I. , Proest, G.
And Halter, U. (2001) ‘Benefits from aerobic exercise in patients with major depression: A pilot study’ Rationale of the Study In view of the fact that a growing number of studies report positive effects of exercise on depression and suggest that even a single bout of exercise could be effective, the researchers aimed to assess the short-term effects of exercise training programmes on patients with clinical depression. Methods Participants – Patients who had been diagnosed with major depressive disorders were chosen from amongst both in- and out-patients.
They were aged between 18 – 65 years, had had no major change in therapy or hospitalisation in the six weeks prior to the onset of the study, had no associated organic disease and had a score of ? 15 on the HAMD. Experimental Design – For a period of ten days excluding Sundays, the 12 patients selected were subjected to supervised training consisting of daily walking on a treadmill during which time physical parameters such as the Heart Rate, Blood Pressure and Capillary Lactate concentration were regularly measured.
Outcome Variables – Maximal Physical Performance as measured by a modified Bruce Treadmill Test and severity of depression as measured by the HAMD were assessed at the beginning and the end of the programme by a psychiatrist. Response to therapy was seen as having taken place when there was a reduction of 50 % or more or a final score of ? 10 in the HAMD. Results Significant improvements were observed in 6 of the twelve subjects, slight improvements in 2, while the remaining four had no change in the severity of their symptoms.
Szabo, A. , Billett, E. amd Turner, J. (2001) ‘Phenylethylamine, a possible link to the antidepressant effects of exercise’ Rationale of the Study Exercise has been found to be beneficial in improving mood in depressed patients although its mechanism of action is unknown. The study sought to provide new information about the effects of exercise by exploring the relationship between exercise and plasma levels of phenylethylamine, an endogenous neuroamine whose levels are found to be significantly lowered in depressed patients.
Methods Participants – 20 healthy male volunteers with an average body mass index of 23. 5 and resting heart rate of 64 beats/minute who were in the habit of exercising regularly were chosen. Experimental Design – Participants were asked to refrain from exercise for 24 hours prior to the onset of the study and then were commenced on treadmill exercises at 70 % of their maximal heart rate reserve (MHRR) for 30 minutes in the laboratory.
Outcome Variables – Urinary levels of phenylacetic acid (a product of metabolism of phenylethylamine) in a 24 hour sample of urine collected on day ‘0’ were compared with the levels in a 24 hour sample collected on day ‘2’ after the completion of the exercise schedule. Results There were increases of between 14 – 572 % in the levels of urinary phenylacetic acid (average 176mg/24 hours) in 18 of the 20 study participants when compared with the pre-exercise levels (average 99. 4 mg/24 hours) pointing to increased plasma concentrations of phenylethylamine.
This increase is significant enough to warrant further research into the nature of the relationship between phenylethylamine and exercise. Discussion Depression as a Major Health Problem Major Depressive Disorder (MDD) is a significant health problem which is expected to rank second only to coronary heart disease as a major disease worldwide by the end of the year 2010 (Lawlor and Hopker, 2001; Blumenthal et al. , 2007). In 2001, the WHO reported that mental disorders accounted for almost 30 % of non-fatal diseases in Australia.
Of these disorders, depression was the leading cause of non-fatal disease burden accounting for nearly 4 % of the total burden (Mathers et al. , 2001). Depression treatment guidelines recommend the use of antidepressant medication in conjunction with psychological therapeutic measures such as cognitive behavioural therapy (CBT) on interpersonal therapy (Vos et al, 2004). Research however has shown that sufferers are slow to seek professional help (Vos et al, 2004) and even when they do, they are rarely compliant with antidepressant medication (Lawlor and Hopker, 2001).
Furthermore since a proportion of patients do not benefit from pharmacological interventions, alternative therapeutic measures have gained increasing significance over the past few decades (Callaghan, 2004). The use of behaviourally-based approaches such as aerobic exercise in conjunction with other methods of management of some medical conditions is an accepted practice amongst some medical practitioners because of their scientific basis.
The exact nature of the link between exercise and depression is unknown although a number of mechanisms have been suggested including: the benefits of social interactions in increasing self-esteem and reducing the incidence of negative thoughts; increased plasma concentrations of endorphins and neuroamines such as phenylethylamine and serotonin; reduced stress reactivity and activity related increases in self-efficacy and control (Lawlor and Hopker, 2001; Harris et al. , 2006).
The studies being reviewed attempted to add to the body of research into exercise and depression by confirming the positive effects of exercise on depression as well as to relate plasma levels of neuroamines to exercise. Problems with the research Research into the relationship between exercise and depression has been plagued by methodological limitations which often render their results inconclusive (Veale et al. , 1992; Lawlor and Hopker, 2001; Harris, Cronkite and Moos, 2006; Blumenthal et al.
, 2007) although Lawlor and Hopker (2001) have also noted that these limitations are also present in research into the effect of other interventions on depression and suggest that there is a need for improved research into depression in general. The methodological limitations of previous studies were acknowledged by most of the researchers who made attempts to rectify this in their research studies. Despite this however, there were still some shortcomings identified within the papers studied for this paper.
The sample sizes for most of the studies were fairly small and it has been acknowledged by researchers such as Rethorts, Wipfli & Landers (2009) that a large sample size is essential to ensure the quality of any research project. While it is acknowledged that it is difficult to motivate depressed individuals to participate in physical activity (Harris, Cronkite and Moos, 2006), to ensure greater quality of research, there is a need for larger sample sizes.
In addition, all of the four studies examined physical activity, serum concentrations of neuroamines and depression scores at only two assessment periods. It has been acknowledged that to increase reliability and precision, researchers need to utilise more than two waves of data (Harris, Cronkite and Moos, 2006). It must also be noted that depression is a chronic condition estimated to be recurrent in 80 % of cases (Voos et al, 2004) and for that reason conducting studies on exercise without attempting long term follow-up of participants is far from adequate.
Furthermore, since all of the four studies used willing participants or volunteers, the impact of the personal meaning of exercise to the individuals and their personal motivation to exercise cannot be ignored as it could introduce a degree of unreliability to the results (Harris, Cronkite and Moos, 2006). Significant Findings The results of all of the studies suggested that there is a positive relationship between exercise and elevation of mood in depressed patients.
Researchers have suggested that social interactions as well as the occurrence of personalised care from physical trainers are of significant benefit to the participants. However, some researchers as typified by Szabo et al. (2001) have also identified that there are also biochemical changes within the bodies of patients exercising. This would lead one to conclude that despite the methodological limitations of the studies, there is a positive relationship between exercise and depression which is worth exploring in future depression based research.
Possibilities for Future Research Exercise is increasingly accepted as a useful adjunct to pharmacological therapy for depression. However, for exercise to be useful as an accepted therapeutic measure there is a need for determination of the nature, duration and frequency of exercise that will result in optimal clinical changes in patients (Lawlor and Hopker, 2001). It should also be noted for studies to be completely reliable there is a need for them to be fully randomised and scrutinised by blind assessors for complete validity.
Finally, most of the current studies involve single observations on two occasions only (Harris, Cronkite and Moos, 2006). For an accurate examination of the effect of exercise on depression therefore, there is a need for the conduction of long term studies which will follow up participants for longer periods of time. Conclusion Depression is a chronic condition affecting millions of individuals worldwide. There is no definitive treatment schedule available since individuals vary in their responses to each therapeutic option. Exercise is increasingly accepted as a useful adjunct to traditional methods of treatment.
While research into this effect is characterised by many methodological limitations, current evidence strongly suggests that it is effective. Therefore, it can be recommended as an additional option for treatment of depression. References Blumenthal, J. A. , Babuak, M. A. , Doraiswamy, K. , Watkins, L. , Hoffman, B. M. , Barbour, K. A. , Herman, S. , Craughead, E. , Brosse, A. , Waugh, R. , Hinderliter, A. and Sherwood, A. (2007) ‘Exercise and Pharmacotherapy in the treatment of Major Depressive Disorder’ Psychosomatic Medicine 69(2007): pp. 587 – 596 Callaghan, P.
(2004) ‘Exercise: A neglected intervention in mental health care? ’ Journal of Psychiatric and Mental Health Nursing 11(2004): pp. 476 – 483 Dimeo, F. , Bauer, M. , Varahram, I. , Proest. G. and Halter, U. (2001) ‘Benefits from aerobic Exercise in patients with major depression: A pilot study’ British Journal of Sports Medicine 35(2): pp. 114 – 117 Harris, A. H. S. , Cronkite, R. and Moos, R. (2006) ‘Physical Activity, Exercise Coping and Depression in a 10 year cohort of depressed patients’ Journal of Affective Disorders 93(2006): pp. 79 – 85 Lawlor, D. A. and Hopker, S. W.
(2001) ‘The Effectiveness of exercise as an intervention in the management of depression: a systematic review and meta-regression analysis of randomised controlled trials’ British Medical Journal 322(March 2002): pp. 1 – 8 Mathers, C. D. , Vos, T. E. , Stevenson, C. E. and Begg, S. J. (2001) ‘The burden of disease and injury in Australia’ Bulletin of the World Health Organisation 79(11): pp. 1076 – 1084 Rethorst, C. , Wipfli, B. , Landers, D. (2009). ‘The antidepressive effects of exercise’ Sports Medicine, 39(6): Retrieved from the MEDLINE database 18th July 2010 Szabo, A. , Billett, E. and Turner, J.
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