Omega 3 fatty acids have been shown to be clinically more effective than a placebo in the treatment of mild to moderate depression in the elderly. Yaser Tajalizadekhoob et al studied the effect of low-dose omega 3 fatty acid supplementation as an alternative to antidepressant treatment for the elderly (1). One popular source of these beneficial fatty acids is fish and fish oil. Fish oil was used as the source of Omega 3 fatty acids in the intervention group of this study. Throughout the remainder of this paper the limitations/strengths will be discussed with regard to their support of the potential benefits of omega 3 fatty acids supplementation in the elderly. As well as the means whereby a randomized clinical trial is one of the stronger study designs to investigate the effectiveness of this alternative form of treatment in the elderly population.
The setting of this randomized clinical trial (RCT) took place at a private government funded care facility. The trial consisted of 66 mild to moderately depressed elderly participants divided into two groups: 33 in the treatment group and 33 in the control group. One low-dose omega 3 fatty acid supplement was given daily to each member of the fish oil group and a placebo was administered at the same time to the control group. At the end of the RCT the results showed statistical significance for the fish oil group in their short form Geriatric Depression Scale (GDS-15) scores. The fish oil group and control group were divided into all participants and participants not using anti-depressants to see if there was actually an effect on the participants using the fish oil supplement vs. those using the antidepressant and the fish oil. In the fish oil group the scores from baseline to final for all participants had a difference of 1.24. The significance of these scores is relative. Compare that to the placebo group whose mean for all participants gave a difference of just 0.30. Showing a positive relationship between omega 3 fatty acid use and improvement in depressive symptoms. According to the study, when the groups were divided into all participants and non-antidepressant groups “…differences in clinical response were more evident…” this can been seen when comparing the difference of 1.47 for the non-antidepressant fish oil group to the control/placebo group’s difference of 0.08. According to these results the non-antidepressant fish oil group showed a significant improvement in scores meaning that their overall depressive symptoms improved as was seen in the all participants group (1).
Randomized controlled double blind clinical trials (RCT) are the gold standard for study design choice. This type of research provides data with the least amount of bias. That being said Tajalizadekhoob et al research team involved in the low-dose omega 3 fatty acid depression treatment study used RCT to determine the effects of fish oil supplementation as treatment. In addition this study included a list of the number of withdrawals from the study as well as the reason for withdrawal. The reason this is important is because the number of withdrawals and the reason for withdrawal could indicate a possible problem related to the treatment in the study. As with this experiment the reason behind participant withdrawal was natural related to death or other health problems requiring their removal. Another strength of this study is the use of blinding for the researchers, staff administering the fish oil/placebo, and the statistician preparing the statistics. Blinding is one of the trademark strengths of RCT because it eliminates particular bias related to the researcher and participant. Lastly, the participants were selected based on an exclusion/inclusion criteria consisting of 10 points, a mini-mental state examination (MMSe) used in diagnostic testing for Alzheimer’s and dementia which would eliminate them from the study and GDS scores, clustering, and randomization of remaining participants. All of these factors created an environment possible to deduce the true effect of omega 3 fatty acid supplementation on the improvement in depressive symptoms in the elderly population. This study did not describe the details of the statistics in the discussion section, which left the reader to draw conclusions on their own. The data was provided in a table but little information was given as to the exact outcome extracted from the data in statistical jargon as well as an explanation of what the numbers were indicating.
Bias is a difficult factor to eliminate when conducting one of the many types of study designs, especially in clinical trials. One of the concerns in this study was the identification of the fish oil by flavor because of the fishy taste of the pill as well as by the color. One way this was eliminated was by using a placebo that was the same color as the fish oil pill and by masking the fish oil flavor to match the placebo. In a clinical trial conducted in Pavia in a nursing home by Rizzo et al. the participants in both groups were administered the appropriate oil with the addition of lemon oil to disguise the fishy flavor. This eliminated identification bias (2). One marked difference Tajalizadekhoob’s study compared to Rizzo et al.’s trial was that the target population was strictly female. A possible reason for this is better understood by citing a similar study conducted by Grace Giles et al. at the International Life Sciences Institute. She found that rates of depression are higher for women than for men, which may account for the primary selection of women in Rizzo’s study (3). Which may account for the reason Rizzo’s study focused on elderly women. This may make Tajalizadekhoob’s study less efficacious. In a meta-analysis/review of the literature regarding antidepressant use and omega-3 fatty acid supplementation Lin P, Mischoulon D, Su K, et al discovered that it was important to focus on a specific population of interest within the general population instead of “…a heterogenous group of individuals with depressive symptoms of varying severity…” The conclusion also stated that to determine this specific population the researchers should use standard diagnostic procedures to recruit participants (4). The importance of specific diagnostic procedures is clearly identified by the researchers of this meta-analysis/review. Tajalizadekhoob’s study used well-defined exclusion/inclusion criteria to determine the participants in the study and to make sure they met the requirements needed.
Overall, this study held many strong points: RCT study, parameters in place to eliminate bias to increase the validity of the results, the participants were a well-defined population and the results included information regarding further research needed due to results of the study. The outcome of this study provides promise for an alternative treatment for depression but because the research is not conclusive stating that the benefits related to depression based on the usage of fish oil has repeatedly shown the same positive results that any consideration of this as an alternative form of treatment should be discussed with a personal healthcare provider.
1. Tajalizadekhoob Y, Sharifi F, Azimipour S, et al. The effect of low-dose omega 3 fatty acids on the treatment of mild to moderate depression in the elderly: a double-blind, randomized, placebo-controlled study. European Archives Of Psychiatry & Clinical Neuroscience. December 2011;261(8):539-549
2. Rizzo A, Corsetto P, Rondanelli M, et al. Comparison between the AA/EPA ratio in depressed and non depressed elderly females: omega-3 fatty acid supplementation correlates with improved symptoms but does not change immunological parameters. Nutrition Journal. January 2012;11(1):82-92.
3. Giles G, Mahoney C, Kanarek R. Omega-3 fatty acids influence mood in healthy and depressed individuals. Nutrition Reviews. November 2013;71(11):727-741.
4. Lin P, Mischoulon D, Su K, et al. Are omega-3 fatty acids antidepressants or just mood-improving agents? The effect depends upon diagnosis, supplement preparation, and severity of depression. Molecular Psychiatry. December 2012;17(12):1161-1163.
5. source for photo: http://www.hearthealthyonline.com/images/img_omegafattyacidslg_1a.jpg
Reviewed by Viktoriya Wolff