Exercise as it relates to Disease/The effects of exercise training on individuals suffering from bipolar disorder

Bipolar Disorder
Bipolar disorder is a mental condition characterised by extreme mood swings, going from 'highs' to 'lows' at varying frequencies, the most severe form previously being called 'manic depression. Although all individuals with bipolar disorder are classified as one, there are many different responses to the mental state itself, depending on the individual affected and their current lifestyle, stress levels and culture. Some sufferers experience daily mood swings, while others can dwell in either end of their mood swing for months at a time. In some cases, individuals will have psychotic experiences and even be hospitalised for a time.

Prevalence
Bipolar disorder worldwide will affect one in every 100 people, while in Australia alone, an estimated 1.8% of males and 1.7% of females have had bipolar disorder in their lives while in the US, 2.6% of adults are affected by bipolar disorder.

===Types of Bipolar Episodes === There are four main types of responses to Bipolar Disorder:

Mania
For those in a manic state, it is common to feel more energetic, more creative and euphoric. People also begin to feel invincible and powerful which can lead to dangerous decisions. Mania is characterised by a lack of sleep, racing thoughts, impaired judgement and reckless actions.

Hypomania
Hypomania is a less severe form of mania. People in a hypomanic state will still feel euphoric and productive, but they never lose touch from reality in the same way that manic individuals tend to. Hypomanic people will usually simply come off as being in an unusually good mood and will often escalate into a manic state or enter into a depressive episode.

Depression
Unlike normal depression, bipolar depression is not treated with the use of anti-depressants for fear that they will make the individual's state of mind worse, spiraling them inbetween manic and depressive states. Bipolar depression is characterised by irritability, moving and speaking slowly, sleeping a lot and unnecessary weight gain.

Mixed Episodes
Commonly perceived as the worst mental state for a bipolar individual, someone experiencing mixed episodes will feature symptoms of both mania and depression, often switching between the two feelings very rapidly. Mixed episodes often see agitation, irritability, anxiety, insomnia and racing thoughts. Bipolar sufferers with frequent mixed episodes have a higher risk of suicide.

Bipolar I Disorder
The more severe version of the two basic bipolar varieties, Bipolar I is the classic manic-depressive form which features mania and mixed episodes

Bipolar II Disorder
Bipolar II disorder features episodes of hypomania and severe depression and does not include full manic episodes.

Cyclothymia
Milder variety of bipolar disorder incorporating cyclical, more predictable mood swings.

==Current Research == Currently, there has not been very much research published on the direct effects of exercise on bipolar disorder itself, instead focusing on certain parts of the disorder including depression anxiety and stress. Undoubtedly, future research will emerge concerning exercise and its direct benefits or lackthereof on bipolar disorder specifically.

Where is the research from?
This was a study of 98 patients admitted to a private psychiatric unit in Melbourne, Australia, with primary diagnosed bipolar disorder over a 24-month period. The 24 individuals who regularly attended the walking group voluntarily were known as the 'participants', while the other 74 individuals who did not attend were referred to as 'non-participants'.

What kind of research was this?
This study is a retrospective cohort study with a significantly larger non-exercising group than exercising. One group was given an opportunity to undertake physical activity in the form of walking regularly, while the other 'non-participant' group acted as the control group.
 * Advantages: A cohort study is useful in determining what the effect of a given intervention is on a known population. Cohort studies allow the researchers to examine multiple outcomes of a given exposure
 * Disadvantages: With retrospective cohort studies, it is important to have large numbers of subjects to study the effects of an intervention in rare exposures and is susceptible to selection bias. There is also often an absence of data on potential issues given that the data is often recorded in the past.

What did the research involve?
The 24 exercising participants were measured pre- and post-assessment and compared against their non-exercising counterparts using the clinician-rated Clinical Global Impression Severity (CGI-S) and Improvement scales (CGI-I) and the self reported 21-item Depression Anxiety Stress Scale (DASS) as primary outcome measures.

What were the basic results?
It was found that the 'participant' and 'non-participant' groups did not vary greatly in admission CGI and DASS measures. The major result noted from this study was lower Depressions Anxiety Stress Scale scores for participants post-intervention (p=0.049). This DASS score decrease noted improvements in:
 * Self-disparaging
 * Pessimism
 * Enjoyment and satisfaction
 * Ability to become interested
 * Apprehensiveness
 * Ability to relax
 * Irritability

While the differences between the groups in terms of CGI measures did not change drastically post-assessment, it was found that participants left with slightly lower scores than non-participants for their DASS scores (p=0.005), indicating a lingering effect of exercise on those suffering from bipolar disorder.

How did the researchers interpret the results?
It was concluded that with this trial, the path was paved for further research on the therapeutic role of physical activity in the treatment of bipolar disorder due to the evidence to suggest that there is a positive effect on the sufferers' mental states that also persists for a period of time following an exercise intervention. The 'participant' group had shown definite decreases in their self-reported Depression Anxiety Stress Score, including all sub-divisions (depression, anxiety, stress) when viewed subjectively.

What conclusions should be taken away from this research?
Physical activity, even at low intensities such as walking, has been shown to improve Clinical Global Impression slightly, and based on the participants' self-reported Depression Anxiety Stress scores, they felt significantly better post-intervention. However, with such a small sample size of 98 individuals, only 24 of whom exercised, it cannot be assumed that these results would carry over to all other population groups. Similarly, depending on the severity of the suffering individual's bipolar, exercise may have a detrimental effect rather than beneficial. This is an unknown because the study carried out by Ng, et al. did not have any direct measure of manic or hypomanic symptoms, instead focusing much more on the 'low' feelings associated with bipolar disorder. It is not known what the effect of exercise, at any intensity, would be on the 'high' feelings. Someone in a manic state who is exercising regularly could be elevating their manic symptoms even further as there is already established evidence of exercise increasing overall happiness and decreasing depressive symptoms.

What are the implications of this research?
Ultimately, the current research has only really looked at the therapeutic role of exercise in aiding those suffering from Bipolar disorder and the short-term lasting effects of exercise upon them. While this is useful information, and provides strong evidence that exercise will indeed benefit bipolar sufferers, for a more complete view of the disorder and how it is affected by exercise, a wider range of exercising mediums need to be examined; not just low intensity walking. This could include High Intensity Interval Training (HIIT), low-impact aerobic training, resistance training and the like. Also, with the disadvantages of a retrospective cohort study of such a small population, it would be beneficial to have more randomised controlled trials.