Biological Treatments of Major Depressive Disorder & Phobias (DP IB Psychology)

What are Biological Treatments?

• Biological treatments are used to treat disorders such as MDD and phobias using drug therapy

• The use of drug therapy is in line with the biomedical approach to treating disorders

• The depressed or phobic patient is prescribed a drug that will work on the physical cause of the disorder e.g. brain chemistry

• Antidepressants are widely used to treat a range of disorders as well as MDD e.g. OCD, GAD, PTSD which means that they treat the symptoms of depression and also the symptoms of anxiety disorders (which include phobias)

• Examples of widely prescribed antidepressants are:

  • Selective Serotonin Reuptake Inhibitors (SSRIs): they work by increasing the amount of serotonin available in the synaptic cleft e.g. fluoxetine, citalopram

  • Serotonin-Noradrenaline Reuptake Inhibitors (SNRIs): they work in a similar way to SSRIs but are considered more effective than SSRIs e.g. duloxetine, venlafaxine

  • Monoamine Oxidase Inhibitors (MAOIs): they work by increasing the amount of neurotransmitters such as serotonin in the brain e.g. phenelzine, tranylcypromine

Antidepressants may provide a quick, easy and cheap solution for a range of disorders.

How are biological treatments used to treat MDD & phobias?

• The most widely prescribed form of antidepressant is the SSRI which works to prevent the reuptake of serotonin in the synaptic cleft back into the presynaptic neuron and thus increase available serotonin in the brain

• Serotonin levels have been linked to depressive symptoms (e.g. low or disrupted levels of serotonin have been implicated in the onset of MDD) - this is known as the monoamine hypothesis

SSRIs work by preventing serotonin molecules from being absorbed back into the presynaptic neuron.

• Phobias are less likely to be treated with SSRIs than MDD is

• MAOIs are less likely to be prescribed for MDD as they tend to work best on anxiety disorders such as panic disorder, phobias and PTSD

• MAOIs are a long-established drug therapy prescribed for a range of disorders, having been introduced in the 1950s

• Phenelzine, which is a MAOI, has been found to be effective in reducing the symptoms of phobias, social phobia in particular

Evaluation of biological treatments for MDD & phobias

Strengths

• Drug therapy has resulted in far fewer people being hospitalised, instead patients are able to manage their disorder, giving them more freedom and autonomy as a patient

• Drug therapy is cheap and immediately available unlike therapy e.g. CBT,  which requires a trained therapist, is conducted over months or even years and in many cases means that the patient has to join a waiting list for treatment

Weaknesses

• SSRIs are the most common treatment for MDD, but there is still some (quite heated) debate as to their efficacy in treating MDD and other disorders i.e. some clinicians argue that they produce a placebo effect

• The debate surrounding antidepressants and the monoamine hypothesis generally may be due to multiple factors, probably based on the idea that depression is a group of disorders with several underlying pathologies rather than one distinct disorder (Lee et al. 2010)

Which studies investigate biological treatments for MDD & phobias?

• Kroenke et al. (2001) - SSRIs used to treat MDD

• Liebowitz et al. (1988) - MAOIs used to treat phobias