What is depression?
Depression, also known as major depressive disorder, is characterised by prolonged experiences of persisting low mood; which may induce feelings of sadness, loneliness and hopelessness. Such overwhelming emotions could further lead to a loss of interest in participating in activities that were once enjoyed, creating sleep problems, fatigue and interference to cognitive abilities.
How is depression diagnosed?
The primary tool used in the field of clinical psychology in Australia to help diagnose mental health disorders is the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Diagnostic criteria for major depressive disorder (MDD) are as follow:
- Depressed mood most of the day, nearly every day
- Markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day
- Significant weight loss when not dieting or weight gain, or decrease or increase in appetite nearly every day
- A slowing down of thought and a reduction of physical movement (observable by others, not merely subjective feelings of restlessness or being slowed down)
- Fatigue or loss of energy nearly every day
- Feelings of worthlessness or excessive or inappropriate guilt nearly every day
- Diminished ability to think or concentrate, or indecisiveness, nearly every day
- Recurrent thoughts of death, recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide
What causes depression?
Decades of research have attributed the cause of depression to either biological factors (e.g., neurotransmitter imbalance, genetics), environmental factors (e.g., traumatic life events) or a combination of both.
Twin studies examining the heritability of clinical depression suggested that heritability is approximately 40-50%. This suggests that genetic factors may play a role in around 50% of most cases of depression and environmental factors could account for the remaining 50% (Levinson, 2006). Despite so, as of now, there is no definitive answer to which whether depression is fully attributable to genetics or environmental factors. Genetics may play a role in predisposing an individual to be more susceptible to developing depression, when coupled with environmental factors, in the future.
- Neurotransmitter imbalance
Early studies of major depressive disorder attributed the causes of depressive symptoms to the imbalance of neurotransmitter in the brain. The dysregulation of serotonin, dopamine and norepinephrine (or noradrenaline) are believed to play a substantial role in the manifestation of depressive symptoms.
- Traumatic events
Direct or indirect experiences with traumatic life events can heavily impact a person’s psychological state. It has been well documented that experiences with traumatic events can lead to a diagnosis of clinical depression and/or post-traumatic stress disorder (PTSD). Stressors in the immediate environment such as emotional abuse, neglect or daily stress may also lead to a depressive episode.
How can depression be treated?
Depression can be treated by both pharmacological (e.g., antidepressants), psychological treatments (e.g., Cognitive Behavioural Therapy (CBT)) or a combination of both. Pharamacological interventions intend to address the principle belief that depressive symptoms arise as a result of imbalance of neurotransmitters. Thus, antidepressants aim to manage depressive symptoms by re-balancing neurotransmitters in the brain. However, antidepressants tend to have adverse side effects and are often not well tolerated by many. Common side effects of antidepressants may include:
- Weight gain/weight loss
- Dry mouth
- Blurred vision
Psychotherapy is another popular and often preferred option for treating anxiety and affective disorders. A meta-analysis by Bandelow et al., (2015) showed that mindfulness, acceptance and commitment therapy (ACT) and cognitive behavioural therapy (CBT) are effective in reducing anxiety and depressive symptoms. Both CBT and ACT capitalises on the neuroplasticity of the brain by training it to improve certain cognitive processes to produce a long-term effect. More traditional forms of psychotherapy such as psychodynamic psychotherapy (PPT) is also found to be effective in treating depressive symptoms and anxiety.
- Cognitive Behavioural Therapy (CBT)
- Psychodynamic psychotherapy (PPT)
- Acceptance and Commitment Therapy (ACT)
- Positive Psychology (PP)
Bandelow, B., Reitt, M., Röver, C., Michaelis, S., Görlich, Y., & Wedekind, D. (2015). Efficacy of treatments for anxiety disorders: a meta-analysis. International Clinical Psychopharmacology, 30(4), 183-192.
Black Dog Institute
Butler, A. C., Chapman, J. E., Forman, E. M., & Beck, A. T. (2006). The empirical status of cognitive-behavioral therapy: a review of meta-analyses. Clinical psychology review, 26(1), 17-31.
Jones, E. E., & Pulos, S. M. (1993). Comparing the process in psychodynamic and cognitive-behavioral therapies. Journal of consulting and clinical psychology, 61(2), 306.
Levinson, D. F. (2006). The genetics of depression: a review. Biological psychiatry, 60(2), 84-92.
Shalev, A. Y., Freedman, S., Peri, T., Brandes, D., Sahar, T., Orr, S. P., & Pitman, R. K. (1998). Prospective study of posttraumatic stress disorder and depression following trauma. American Journal of psychiatry, 155(5), 630-637.
Shedler, J. (2010). The efficacy of psychodynamic psychotherapy. American psychologist, 65(2), 98.