Depressed? Eat Some Fish

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.