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Nutritional Science
NS 1150
David Levitsky

Regan 1 Christina Regan NS 1150 Professor Levitsky 11 Nov. 2013 Cognitive Decline and Omega-3 FattyAcids Cognitive decline and the role that omega-3 fatty acids play in it’s progression have been popular topics and sources of controversy for the past decade or so. Because the size of the population of senior citizens is increasing with the aging of the baby boomer generation, the number of cases ofAlzheimer’s disease and dementia are expected to drastically increase.As a result, research into this topic, and the role that nutrition plays, is of increased importance. The challenge that we, as individuals, face is trying to determine which studies are based on good, reliable science and which studies are not. In December of 2005, Dr. Martha Morris, Dr. DenisA. Evans, Dr. Christine C. Tangney, Dr. Julia L. Bienias, and Dr. Robert S. Wilson published their study in theArchives of Neurology. It was titled Fish Consumption and Cognitive Decline WithAge in a Large Community Study and dealt with the correlation between the consumption of omega 3 fatty acids and cognitive decline. The study, however, did have its strengths and weaknesses. One of the strengths of the study was that it took place over the span of six years.Along trial period helps to validate the observations seen by the researchers. Over a long period of time however, all of the data collected reduces the impact of outliers observed in individual results and in the results of the overall group. It also provided the human body with enough time to adequately process and respond to the levels of omega three fatty acids.Also, because the study Regan 2 deals with cognition, the long time period gave the researchers a good understanding of the progression of mental decline among the patients and among the various groups. Another area that was a source of many strengths and weaknesses for the study were the participants. In the beginning of the study, there were 6158 people but by the end there were only 3718 participants left.All of the participants were over the age of sixty-five, so not all of them were alive by the end of the study. However, the large sample size was able to compensate for the high drop out rate. The old age of the participants also served as a source of problems because the researchers had to take the multitude of health problems into consideration when they analyzed their results. The participants were from the Chicago area and came from all different backgrounds, races, and genders. This variety served to rule out any doubts that the effects of omega three fatty acids are only seen in a certain category of people. Another strength of the study was the way in which they analyzed the data that they were given. The researchers looked at the data from a multitude of ways in order to account for different phenomena and variables. Models were adjusted for age, sex, race, education, cognitive activity, physical activity, alcohol consumption, total energy intake, depressive symptoms, heart disease, hypertension, stroke history, and diabetes mellitus. They also adjusted models to account for intakes of saturated, polyunsaturated, vitamin E, niacin, vitamin c, and trans fats (Morris, Evans, Tangney, Bienias, and Wilson, 2005.) However, one of the weaknesses was that they did not adjust models for cardiovascular problems or for fruit and vegetable intakes initially, but these categories were later incorporated. One of the weaknesses of this study was that some of the data was self reported. Information about heart disease, hypertension, stroke history, and diabetes mellitus were all provided by the participants. This could be an issue because people have been known to Regan 3 exaggerate information in order to make themselves look better. However, one strength of this study was the fact that it was observational. The researchers did not impose any treatments or changes on the participants. This is beneficial because the people get to continue their daily diet, which means that they are less likely to deviate from their category. The categories that the researchers looked at included those who ate a fish meal less than once a week, those who ate about one fish meal per week, and those who ate more than one fish meal per week. Participants were assigned to one of these categories after they completed a Food Frequency Questionnaire, during the trial, participants were also asked to keep track of their diets. This Food Frequency Questionnaire, or FFQ, and self-reporting diets are also sources of concern because there is no way to determine if a participant was lying. Overall, the researchers did observe a correlation between the number of fish meals per week a participant consumed and cognitive decline.Astatistical significance was observed as the p-value associated with a decreased rate of cognitive decline and the people that ate one fish meal per week was 0.02 and the p-value associated with people that ate two or more fish meals per week was 0.04. Through cognitive tests, they found that cognitive decline was much slower in people that ate fish meals at least once per week.Although this study does have its weaknesses, it is still very strong and I believe that the data can be trusted. The researchers accounted for many different factors in order to rule out any other possibilities for the results observed. They also had a huge population with a lot of variation. Because of these factors, I believe that it is safe to assume that these results are valid. Dr. Vanessa Danthiir, D. Nicholas R. Burns, Dr. Ted Nettelbeck, Dr. Carlene Wilson, and Dr. Gary Wittert published a study titled “the older people, omega-3, and cognitive health (EPOCH) trial design and methodology:A randomised, double-blind, controlled trial Regan 4 investigating the effect of long-chain omega-3 fatty acids on cognitive ageing and wellbeing in cognitively healthy older adults.” It was published in the Nutrition Journal in 2011. This study, however, has many pros and cons to the way in which it was executed and analyzed. This study was a “parallel, 18 month, randomized, double-blind, placebo-controlled, intervention with assessment at baseline and repeated 6-monthly (Danthiir, Burns, Nettelbeck, Wilson, Wittert, 2011.)” There are many advantages to the way in which the study was set up. First of all, the study was double-blind. This means that the administrators, principle investigators, and the participants were all unaware of the type of supplements that they were administering or receiving. This is a very good indication of the validity of the results because it means that no bias was able to affect the data. Next, there were many advantages to the way in which the groups were assigned. The groups were randomized and one of them was a placebo, or control group. The presence of a placebo group is important because it allows the result from each group to be compared so that it can be determined if the results observed are really a result of the omega-3 fatty acid supplement. Randomization is also an important factor because it shows that no bias was used when the groups were being assigned. There are, however, some cons with the design of the study. The sample size of the study was 391 people. Compared to the previous study, this sample size is very small. However, a trial with close to 400 people is still very impressive and the results of this study cannot be overlooked because of this fact. Furthermore, 53.7% of the participants were females and 46.3% of the participants were male. It would be better if the demographics of the participants were more evenly distributed between sexes, however, these percentages are still very sound. Participants were all in between the ages of 65 to 90 and were recruited by “agencies and organizations from senior citizens, public advertisements, and media releases (Danthiir, Burns, Regan 5 Nettelbeck, Wilson, Wittert, 2011.)” This can be viewed as a con because people that often participate in these organizations for senior citizens and people that respond to these advertisements do not often provide a good indication of the composition of the overall population. Usually, these people tend to be more proactive in their health and tend to leave healthier lifestyles. Also the testing period of the study was relatively small. 18 months may not be enough time to fully see the extent of the effects of the omega-3 supplement on cognitive decline. However there are other things that attest to the validity of the study. Participants in the omega-3 supplement group were given capsules and were asked to take 1720 mg of DHAand 600 mg of DHAwhile participants in the placebo were asked to take an equal amount of olive oil in their capsules. The researchers had to ensure that the participants would actually take their supplements. Thy did this by first counting the amount of remaining capsules when the participants came for evaluations. They also had the participants fill out calendars and send them in on a monthly basis. These measures alone, however, are not enough to prevent the participants from falsifying their information. Because of this another measure was taken. Researchers measured compliance by measuring the erythrocyte membrane n-3 LC PUFAstates and the changes in status via blood samples taken at every 6 month assessment.Although this system is not perfect, I think that it is a good way to determine which participants’data can be utilized and which participants’data cannot be utilized in the analysis of the results. The results of the trial were significant. There was a statistical significance between a slower rate of cognitive decline and omega-3 supplements. The p-value was 0.03. Even though this study was not flawless, I believe that the things that the researchers did right far out weigh Regan 6 the things that they did wrong.As a result, I believe that their data and interpretations can be seen as valid. Dr. Johanna Geleijnse, Dr. Erik Giltay, and Dr. Dan Kromhout published a study titled “Effects of n-3 fatty acids on cognitive decline:Arandomized double-blind, placebo-controlled trial in stable myocardial infarction patients” was published in 2012 in the journal of Alzheimers & Dementia. The structural set up of this study was very good. Like the previous study, this experiment was also double-blind which helped to minimize the chance of bias by the researchers, administrators, and the patients. Next, the groups were also randomly assigned. This is also beneficial because it ties to make the groups more indicative of the entire population and is a further measure to decrease the chance of bias. There was also a placebo group. The presence of a placebo group is important because it allows the results from each group to be compared to the results of the placebo group so that the possibility of a placebo effect can be determined. However, 25% of the participants could determine whether or not they received margarine that had added supplements or the margarine that was the placebo. This is because the researchers started all of the participants on the placebo margarine for a couple weeks before they switched some of the participants to a different type of margarine with added supplements. In a future study, I would not include the two week placebo period in the beginning of the trial. I believe that some participants may have been able to detect variations among the different margarines that they many have received and thus the results could have been affected due to a phenomenon similar to that of the placebo effect. This study was also conducted over 40 months, which is a fairly long period of time. This is a positive aspect of the study because it provides the researchers with enough time to see the full of the treatment. Regan 7 However there are some negative aspects of this study. First of all, it only deals with stable myocardial patients and is not indicative of the overall population.Also this study had a very high rate of drop out. In the beginning of the study, 4,837 people were placed into one of the four different groups. ByAugust of 2005, 1,926 people had been dropped from the study because they had not been randomized by that time and the number of participants totaled 2,911. By the end of the study, only 2,522 people had fully completed the experiment. 389 people either did not complete the study because they either died, refused to take the final MMSE test, or refused to take another one of the final examinations. One of the reasons that this study had such a high drop out rate is due to the fact that randomization had to occur beforeAugust 2005 because of financial reasons associated with the MMSE tests. Although the number of subjects that participated in the study is still very large, the fact that so many people dropped out is not an indication of a good study. Furthermore, 78% of the people that were randomized in byAugust 2005 were men. These demographics may be more indicative of the ratio of men and women that suffer from myocardial infarctions, they are not indicative of the total human population between the ages of 60 and 80. One problem with this study can be observed in the way in which certain participants were classified.At the end of the 40 month period of time, some of the patients had no second MMSE score. One of the reasons for this phenomenon is due to the fact that several participants died before the completion of the trial. However, researchers still tried to categorize the deceased participants in whether or not they suffered from cognitive decline. Researchers stated that cognitive decline was present if “the patient died from dementia, the general practitioner stated on the ‘cause of death form’that the patient suffered from dementia or cognitive decline, dementia or cognitive decline was stated in hospital records of patients who had a CVD Regan 8 (cardiovascular disease) event, treatment of anti-dementia drugs was initiated during follow-up, or dementia or cognitive decline was reported by the patient or other persons” (Geleijnse, Giltay, Kromhout, 2012.) Personally, I believe that only participants that completed the entire 40-month trial should be included in the final analy
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