Presented here it is a critical evaluation of biological approach for treatment of depression. Antidepressant are the most common biological treatment for this type of disorder, but treatments such as Electroconvulsive Therapy (ECT), alteration in sleep patterns following body temperature cycle are also used to relief the symptoms of depression. However antidepressant drugs provide an effective and inexpensive help, studies have found that the behavioural effects of these drugs could take over two weeks before showing any benefit and any perceived effect before this period would be a placebo effect (Kalat, 2001). Some studies proposed the existence of a two models markers for depression: Biological/endogenous & psychological/reactive depression. Based on this assumption an endogenous depression would only respond to a pharmacological treatment while a psychological depression would only respond to psychological treatment (Free & Oei, 1989). Further we will evaluate the effectiveness of a combined (cognitive-behavioural therapy and antidepressant) intervention in order to achieve a better outcome on treatment of depression.

Depression is one of the most common illnesses and is characterised by symptoms such as loss of energy, sadness, difficulty in concentration and in the most serious cases the patient can contemplate or commit suicide. Research found that women are more likely to suffer from depression, with depressive episodes more probable to occur between 25 to 44 years old (Kalat, 2001). In 1980, The American Psychiatric Association published a manual that comes to categorise depression into two main types and this categorisation is based on the severity of the symptoms experienced by the patient. On the nonmajor depression type, symptoms are more discrete and treatment with antidepressants are not approved by Food and Drug Administration(FDA) while on Major depression type an antidepressant treatment is required (Kennedy & Eisfeld, 1999). Triggers for depression are unclear but some changes such as biochemical can be found on depressed patients (O'Connell, 2009) and for many years researchers have been trying to establish biological makers in order to understand what causes depression and improve treatments (Rosenzweig, Leiman & Breedlove, 1999). The monoamine hypothesis of depression proposed by Joseph Schildkraut and Seymour Kety in 1967, found a relationship between depression and a decrease of synaptic activity of connections that utilize monoamine, norepinephrine and serotonin transmitters. More specifically, the decreased activity is found on hypothalamic and limbic system circuitry. The dysregulation hypothesis of depression states that a deficiency in regulatory mechanism that rules transmitters operations might be a reason why transmitter system is unable to respond appropriately to external(environmental) and internal needs. The majority of studies on depression has been finding positive answers for biological markers connected to hormonal responses to stress that are related to the hypothalamic-pituitary-adrenal system. One of the reasons is that the hypothalamic-pituitary-adrenal system can be activated by stress and it is believed that stress triggers depression in some individuals (Rosenzweig, Leiman & Breedlove, 1999). Genetics play a important part on development of depression. It well known that individuals that have history of depression in their families are more likely to develop the illness, the risks are even higher for women or if the relative developed depression before age 30. Further researches also found a link between depression and decreased activity in the left prefrontal cortex. Studies showed a high number of individuals became severely depressed after damage on the left hemisphere (Kalat, 2001).

Treatments for depression vary according with the severity of symptoms, but the most common type of treatment makes use antidepressant drugs. As pointed earlier, reasons for brain chemical unbalance found on depressed individuals are not very clear, but is known the certain drugs can help to relieve the symptoms for most people(O'Connell, 2009). Antidepressant drugs can be categorised into four types: tricyclics, MAOIs(Monoamine oxidase inhibitors), SSRIs(Selective serotonin reuptake inhibitors) and atypical antidepressants. Tricyclics acts by preventing the presynaptic neuron from reabsorbing the serotonin or catecholamines after release leading to a continuos stimulation of postsynaptic cell as the neurotransmitters would stay longer in the synaptic cleft. As side effects, patients can develop heart irregularities due a blockage of some sodium channels as well drowsiness, dry mouth and difficult to urinate since histamine and acetylchoine receptors can also be blocked.(Kalat, 2001). By blocking a presynaptic terminal enzyme called MAO(Monoamine oxidase) that is responsible to metabolises catecholamines and serotonin into a nonactive forms, MAOIs drugs allow the presynaptic terminal to have more of its transmitters to release. MAOIs drugs are indicate to patients that show no response to tricyclics drugs, however people taking MAOIs must avoid foods containing tyramine, such as cheese, raising, liver, pickles and man others. The combinations of MAOIs with tyramine can increase blood pressure and in some cases can be fatal. SSRIs and Tricyclics have similar actions with the first having a specific action on serotonin reuptake. The side effects of SSRIs are mild, with patient showing episodes of moderate nausea and headache, however people suffering from a combination of depression and anxiety disorder are advised not to use SSRIs as the drug can, in some cases, produce nervousness. Atypical antidepressants are a mixed of drugs and antidepressants that are indicated for those patients that showed no response to other drugs. Types of atypical antidepressant are: Bupropion that acts inhibiting reuptake of dopamine and in some occasions norepinephrine reuptake. Venlaxafine antidepressant that mainly affects serotonin reuptake, but its effect can be extended to norepinephrine and dopamine reuptakes and nefazodone that bocks type 2A serotonin receptors and can have a mild effect on reuptake blockage of serotonin and norepinephrine. Individuals diagnosed with major depression might need an urgent intervention, this could be a situation where the individual is contemplating or have even tried to commit suicide. In this case Electroconvulsive Therapy(ET) is indicated due to its fast effects. Nowadays the shocks are less intense, however patients receiving ET can suffer from memory loss(Kalat, 2001). Studies based on circadian rhythms of sleep in depressed patients showed abnormal phase relationship in some rhythms of the body together with changes in REM cycles. Therapy developed based on this assumption consist in advise patients to go to sleep 6 hours before the usual time they go to bed and it was noticed a rapid and last improvement in their depression(Rosenzweig, Leiman & Breedlove, 1999).

There are a wide range os studies examining the evidences for biological/endogenous and psychological/reactive models of depression. This concept of two types of depression is based on the assumption that depression can be trigger by an external stressor or develop within the person (Free & Oei, 1989). This two theories gained force with many experiments carried out on 50's and 60's using depressed patients. An intensely investigated endogenous trigger for depression was focused on urinary catecholamine metabolite 3-methoxy-4-hydroxy-phenyl-glycol (MHPG) as was found a link between MHPG and depression. Mix results was achieve with these studies and support for the two type models depression are very week implicating the lead of treatments for depression (Free & Oei, 1989). Several meta-analytic reviews of studies comparing benefits and efficacy of treatments for depression have found that psychotherapy treatments are the most safe and long lasting choice and also raise concerns about the antidepressants side effects. One of this reviews found a 3% evidence in favour of behavioural intervention when combined placebo against tricyclics drugs. In other very interesting review of 9 studies it was concluded that cognitive therapy treatment of severe depression is likely to reduce the risk of relapse (Antonuccio, Danton & DeNelsy, 1995). There are some major problem regarding antidepressant use. One is that they became the main treatment for either minor and major depression and individual prefer be treated with antidepressant ignoring their side effects. This drugs are also known to be used in suicide attempt (Antonuccio, Danton & DeNelsy, 1995). Ethnic variations should be take into consideration when prescribing these drugs as was found that African American are likely to be more sensitive to their side effects (Ahmed & Bhugra, 2006). Caution in prescribing antidepressant should be considered and psychotherapy could also be included on the treatment as evidences suggested that the use of these drugs alone produce poor results. Due to side effect risks, dosage and length of use should be carefully controlled by Doctors (Antonuccio, Danton & DeNelsy, 1995).

Based on evidences presented above we might conclude that a biological approach alone is not efficient to treat depression. The use of antidepressant would be welcome in order to treat neurotransmitters system malfunction that would relief depression symptom, as well in some severe cases when patients are contemplating suicide the ET therapy would be necessary due the fast response of this treatment, however we must take into consideration that antidepressant have a range of dangerous side effects e for some individual, the use of these drugs can be lethal. The psychotherapy should be considered as the first choice for treatment of depression as this approach is low risk and has long last effect. Most studies agreed that for some cases of major depression a combination of antidepressants and psychotherapy would be ideal, but patients should not make use of these drugs for long periods of time. In terms of psychotherapy treatment, the cognitive-behavioural therapy shows to be as effective as drugs even on most sever cases of depression. A study evaluating types of treatment for depression came to the conclusion that despite conventional wisdom there is no data suggesting that biological intervention such as antidepressant is more effective than psychotherapy on treatment of depression(Antonuccio, Danton & DeNelsy, 1995). Considering that drug treatment is always an option and that some patients prefer antidepressant when treating depression, further studies should focus on finding a positive alliance between biological and psychological approach, thus treatment would be improved and individual suffering from depression would experience a less risky treatment with a long last effect.

References

Ahmed, K. & Bhugra, D. (2006). Diagnosis and management of depression across cultures. Psychiatry, 5(11), 417-419.

Antonuccio, D. O., Danton, W. G. & DeNelsky, G. Y. (1995). Psychotherapy versus medication for depression: Challenging the conventional wisdom with data. Professional Psychology: Research and Practice, 26(6), 574-585.

Free, M. L. & Oei, T. P. S. (1989). Biological and psychological processes in the treatment and maintenance of depression. Clinical Psychology Review, 9, 653-688. Kalat, J.W. (2001). Biological Psychology. USA: Thompson Learning.

Kennedy, S. H. & Eisfeld, B. S. (1999). Clinical aspects of depression. Clinical Cornestone, 1(4), 1-16.

O'Connell, G. (2009). Depression: The essential guide. Great Britain: Need2Know.

Rosenzweing, S. M., Leiman, A. L. & Breedlove, S. M. (1999). Biological Psychology: An introduction to behavioural, cognitive, and clinical Neuroscience, Second edition.Massachusetts. Sinauer Associates.