Two Key Studies of Biol Treatments of Major Depressive Disorder & Phobias (DP IB Psychology)
Revision Note
Written by: Claire Neeson
Reviewed by: Lucy Vinson
Kroenke et al. (2001)
Key study one (a biological treatment for MDD): Kroenke et al. (2001)
Aim: To compare the effectiveness of three SSRIs (paroxetine, fluoxetine and sertraline) in treating MDD, using a large-scale randomised clinical trial.
Participants:
573 patients with MDD from 37 clinics across the USA
The participants were aged 19-96 years old (mean age=46 years)
79% of the sample were female; 21% were male
The ethnic distribution of the sample was 84% Caucasian, 13% Black and 3% other
Each patient had been recommended for the study by their main clinician on the basis of their suitability for treatment with SSRI antidepressants
Procedure:
The participants completed a baseline assessment over the telephone and were randomly assigned treatment via one of the SSRIs (189 were given paroxetine; 193 were given fluoxetine; 191 were given sertraline) for a period of 9 months
At intervals of 1, 3, 6 and 9 months each participant completed a 36 item Mental Component Summary Score (MCSS) health scale with standardised questions designed to measure symptoms of MDD
The participants also completed self-reports on multiple measures of other variables (which were designed to be used in conjunction with the MCSS data), for example, social and work functioning, physical functioning, sleep, memory and pain
Results:
79% of participants completed the full 9 month treatment programme
All participants improved similarly, by a mean of between 15 and 17 points on the MCSS
All of the participants saw an improvement in depressive symptoms from 74% at baseline to 32% at 3 months and 26% at 9 months
Conclusion:
SSRIs may be an effective treatment for MDD
The SSRIs paroxetine, fluoxetine and sertraline appear to be similar in their effectiveness for the treatment of MDD
Evaluation of Kroenke et al. (2001)
Strengths
Triangulation of data was implemented via the use of several different measures e.g. MDD symptoms, social functioning, sleep which increases the reliability of the findings
The wide age range of the sample highlights the universal efficacy of SSRIs which increases the external validity of the findings
Weaknesses
It is possible that some of the participants succumbed to the placebo effect i.e. their depressive symptoms improved because they believed that the drug they were taking would work i.e. a psychological rather than a biological explanation of their improvement
As the participants were left to take their medication at home it is possible that not all of the participants adhered to this medical regimen which would mean that their MDD improved for other reasons: if so this would reduce the validity of the findings
Large-scale randomised clinical trials can show the efficacy of specific drugs
Liebowitz et al. (1998)
Key study one (a biological treatment for phobias): Liebowitz et al. (1998)
Aim: To investigate the effectiveness of the MAOI phenelzine as a treatment for social phobia
Participants: 80 patients aged 18-50 years old who had been diagnosed with social phobia.
Procedure:
A lab experiment with an independent measures design: each participant was randomly assigned to one of four groups:
Phenelzine treatment group
Placebo for phenelzine group
Atenolol treatment group (atenolol is a beta blocker drug used to treat hypertension)
Placebo for atenolol group
The participants were given increasing doses of either phenelzine or atenolol or the placebo over the course of 8 weeks
After the 8 week trial period was over the participants were assessed using the Hamilton Rating Scale for Anxiety and the Liebowitz Social Phobia Scale
The Hamilton Rating Scale for Anxiety measures the severity of anxiety symptoms on a scale of 0 to 4 (4=severe)
The Liebowitz Social Phobia Scale assesses the way that social anxiety plays a role in a variety of situations e.g. attending a party, eating in public, public speaking, measured on a scale of 0-3 (3=severe) and 0-3 (3=usually)
Results:
The participants in the phenelzine treatment group had improved scores for anxiety compared to the placebo groups i.e. their social phobia had decreased over the course of the 8-week trial
There was no significant difference seen in the atenolol group when compared to the placebo group i.e. atenolol does not appear to improve social phobia
Conclusion: Phenelzine appears to be an effective treatment for social phobia.
Evaluation of Leibowitz et al. (1988)
Strengths
Independent assessors who were blind to the condition each participant was in i.e. drug or placebo, conducted the clinical assessments which increases the validity of the findings as it eliminates bias
The findings support the idea that phobias should be treated with medication other than SSRIs as the symptoms are more in line with anxiety disorders than depressive disorders
Weaknesses
A sample of 80 participants divided across 4 conditions means that the number of participants per condition is likely to be 20 which decreases reliability due to the reduced statistical power of the sample size.
An independent measures design runs the risk of individual differences affecting the results i.e. some of the participants may simply have more resilience than others and thus be able to deal with their phobias more successfully than others
Key terms: MAOI Beta-blocker Social phobia
Examiner Tips and Tricks
Your examiner will not award marks for the number of evaluation points you use in your critical thinking. You can use just a few evaluation points as long as you discuss them in depth rather than giving a superficial, surface-level analysis of key issues.Make sure you develop each evaluation point so that you discuss each point fully rather than just making a series of statements.
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