Alcohol use is seen as common place cross culturally having been deemed as a safe and enjoyable beverage. It has been worshipped, bought, and banned throughout its existence of over 10 million years. In recent history there has been much debate on whether this fermented beverage is beneficial or detrimental to the overall well being of people. Some doctors support diets plans with one alcoholic beverage per night while others fear its classification as a depressant can negatively effect one’s health. Topiwala et al. (2017) performed an observational cohort study to see the relationship between alcohol’s effect on the structure and function of the brain overtime.
Topiwala et al. research was descriptive utilizing physiological, neuroscientific, and self reports to measure their longitudinal cohort study. Their study Topiwala et al. (2017) had two hypotheses monitoring a predictor variable of light or heavy drinking and a criterion variable of adverse brain outcomes and cognitive decline. For the sake of the critique there will be a focus on the heavier drinking as the predictor variable. They gathered a convenience sample of five hundred and fifteen participants for the sample of Marmot et al. longitudinal on stress and health which studied the relationship between cardiovascular health and stress across a variety of socioeconomic statuses. (Topiwala et al. 2017) This study was quasi-experimental because they only monitored the alcohol intake of individual and did not manipulate due to ethical issues that would arise otherwise. (Topiwala et al., 2017, Marmot et al., 1985) Leary (2012) differentiates longitudinal and time series designs based off of their quasi-independent variable. Marmot et al. used a time as their quasi-independent variable making their study one that uses a longitudinal design, but Topiwala et al. used a nonequivalent control group design. Topiwala et al. (2017) measured alcohol consumption through the use of self-reports of units consumed per week and utilized the variables recorded from the Marmot et al. work which measured alcohol use every 5 years. (Topiwala et al. 2017) Topiwala et al. classified their participants into four groups (abstinent, light, moderate, and unsafe drinking) and measured cognitive function with lexical, semantic, and fluency tests. Additionally, they measured the physiological and neuroscientific effects of alcohol with MRIs on participants to check grey matter and hippocampal atrophy. The abstinent group qualified as the non equivalent control group as they were civil workers but reports less than one drink per week. (Topiwala et al, 2017)
The findings of the study showed that high alcohol consumption resulted in a greater decline in lexical fluency, but not in semantic fluency. (Topiwala et al. 2017) They found that hippocampus atrophy was dose dependent. Henneman et al. (2009) found that hippocampus atrophy resulted in mild cognitive impairment. This mild cognitive impairment can result in a heightens risk of dementia. Similarly Bell et al. (2017) supported that heavy alcohol consumption was associated with not only negative brain outcome but an increased risk in cardiovascular disease. Topiwala et al. concluded that alcohol consumption was consistent in their participants across the duration of the study. They supported the United Kingdom’s revised alcohol guidelines and urged the United States to make similar changes to regulation. These studies show that alcohol could be a modifiable risk for cognitive and cardiovascular impairment.
One of the issues that come with using quasi-experiment design is that their internal validity is not as strong as an experimental design, but Topical et al elite some of the threats to internal validity by having a control group. This control group helps rule out maturation effects that may be effecting the quasi- independent variable. Additionally, because it is low in internal validity their study has high external validity. They also address that their face validity could be incorrect and participants that had hippocampus atrophy could have been prone to drink more resulting in their placement in the unsafe drinking category. (Topiwala, 2017) For reliability this study utilized the CAGE alcohol screening test which possesses repeatability over time and test-retest reliability as they reported in different phases of the study.
They concluded their article with a limitations section that addressed some, but not all of the limitations within the study. It referenced the fact that the sample could not be a true representation of the United Kingdom as they had a convenience sample drawn from a pre-existing study that consisted mostly of educated middle class men, and within the women that were in the study few fell into the unsafe drinking category. (Topiwala, 2017) With all of the studies that use self reports especially when dealing with topics, such as alcohol, it is easy to imagine that a participant might underestimate the amount of alcohol they have consumed. They might also change their responses based off of social desirability bias so their drinking level is more socially acceptable. There was also a portion of participants that had incomplete CAGE data these participants could have been alcohol dependent. (Topiwala et al. 2017) Alcohol dependance could have also been a third variable problem that could possibly manipulate both hippocampus atrophy and the amount of alcohol consumed. A final problem with the study that was not mention was the fact that MRI were only given to participants safe enough to undergo an MRI restricting the variability of the study. (Topiwala et al. 2017)
Christensen refers to the journal article briefly in her exploration of drinking and its effects on the brain. She starts by exploring the benefits of alcohol seen in fad diets, such as the Mediterranean diet. Christensen does a sufficient job at explaining the study’s design and and measures as well as discussing the conclusion of the study. (Christensen, 2017) She does not however bring attention to the various limitations in the study although there was an entire section that listed them.