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The Effects of Alcohol on Memory
The Effects of Alcohol on Memory
San Jose State University
Alcohol is known to have various psychological and physiological effects when it is consumed, and the consumption of alcohol is common for individuals within many societies around the world. The pervasiveness of alcohol and the effects that it has on both the mind and body make it a particularly pertinent area of study within the field of psychology. The physiological changes that psychologists tend examine and find most crucial occur on the neurological level. From the wide variety of effects that alcohol has on individuals, how it alters memory storage and retrieval have been studied extensively.
Studies that have been conducted focus on multiple dimensions of memory and a variety of physiological effects that occur when alcohol is consumed. These studies have attempted to answer the questions of what specific neurological structures are involved when consuming alcohol and what affect the consumption of alcohol has on memory at different levels. The general research consensus is that consumption of alcohol has a wide range of effects on neurological structures that may be related to alterations of different types of memory storage and retrieval.
In a literature review by Moselhy, Georgiou, & Kahn (2001), researchers examined the changes in the frontal lobe that occur with alcoholism. Their findings suggest that alcohol reduces frontal lobe glucose utilization and causes reduced cerebral blood flow, along with other frontal lobe dysfunctions. The researchers found that these changes in the functioning of the brain are potentially reversible, to some degree, with abstinence from alcohol. Furthermore, these researchers posit that the prefrontal cortex is highly connected with other areas of the brain; thus, it is necessary to investigate other neurological structures to understand the full effects of alcohol consumption.
In an experiment by Bjork, Grant, & Hommer (2003), the effect of alcohol on overall brain volume was examined. These researchers wanted to uncover the most significant correlation between brain volume and drinking. In their study, they conducted magnetic resonance imaging (MRI) on the brains of 164 total participants. The participants included 132 male subjects diagnosed with alcohol dependence, the alcoholic group, and 32 male subjects with no history of significant medical illness or psychiatric disorders, the control group. Background information was taken from each of the participants in order to correlate the MRIs with a selection of variables. After conducting MRIs on all of the participants, researchers used segmentation analysis on the images of the participants’ brains in order to detect significant brain alterations caused by alcohol.
Bjork et al. (2003) found participants in the alcoholic group had significantly less brain volume correlated with the number of years of heavy drinking that they had reported. Furthermore, the researchers found that, in comparison with the control group, the alcoholic group had significantly lower brain volume. Brain atrophy in both gray and white matter was detected in the alcoholic group. The researchers discussed their findings as providing further evidence for alcohol decreasing brain volume, and concluded that the most pertinent correlate of decrease in brain volume for the alcoholic group was the number of years of chronic heavy alcohol use.
Researchers Calhoun, Carvalho, Astur, & Pearlson (2005) explored the relationship between behavior, brain function and blood-alcohol levels. These researchers wanted to determine the specific neural pathways that are affected by alcohol, and explain the way in which alcohol affects neural pathways. In their study, they had 10 screened, healthy participants that were split into two groups. 5 participants were assigned to the alcohol group and were given varying amounts alcoholic drinks while 5 participants in the control group were given placebo drinks. All of the participants took simulated driving tests and then were given a functional magnetic resonance imaging scan (fMRI).
The evidence from Calhoun et al. (2005) showed that participants who consumed large doses of alcohol were more likely to drive at higher speeds and collide with other cars. Participants that had a moderate dose of did not drive significantly different than the control group. Through the fMRI scan, researchers found that, as compared with the control group, there was a decrease in brain function located in the lingual gyrus for the alcohol groups. With implementation of correlation analysis, the fMRI scans also revealed that there is a curvilinear relationship between alcohol dose and activation of the prefrontal cortex, with a moderate dose of alcohol giving optimum activation. The researchers concluded that the decrease in function of the lingual gyrus and the decreased prefrontal cortex activation in high doses of alcohol are the neural pathways that are most affected by alcohol for the particular behavior of driving.
Alcohol was shown to slow neural processing and cause a reduction in processing efficiency through a study by Khan & Timney (2007). The researchers attributed the slowing of neural processing to alterations in temporal visual processing. Participants in their study that consumed alcohol were significantly slower in tasks that measured processing speeds. These effects are likely to have significant effects even at moderate levels of drinking, as implicated in a study by Ilan, & Gevins (2001), where the effect of drinking moderate amounts of alcohol during social situations was explored. As indicated by electroencephalographic activity and event-related potential amplitudes, even moderate alcohol consumption under social situations have effects on neurological functioning that last for hours after chemical and behavioral indicators of alcohol consumption are no longer present.
Physiological transformations that occur with consumption of alcohol during adolescence have been inspected by Spear (2002). The use of alcohol might alter the sensitivity of adolescents to the effects of alcohol, which could in some cases lead to increased alcohol consumption to receive reinforcing effects.
Despite all of the research indicating negative physiological effects that are caused by alcohol, there are also benefits associated with drinking alcohol. In a study by Collins, Neafsey, Mukamal, Gray, Parks, Das, & Korthuis (2009), moderate alcohol exposure was shown to trigger a mild-stress response that was associated with anti-inflammatory functioning in the heart, vasculature, and brain. The initiation of this functioning was found to help promote pathways which lead to cellular survival mechanism activation.
Alcohol has been shown to affect memory at various levels, including explicit, implicit, episodic, semantic, prospective, and intrusive types of memories (Duka, Weissenborn, & Dienes, 2001; Paraskevaides et al., 2010; Thoma, Johann, Wähner, Juckel, & Daum, 2008; Garfinkel, Dienes, & Duka, 2006).
How alcohol affects the encoding and retrieval of memories has been examined by researchers Duka et al. (2001). The purpose of their study was to explore the specific components and degree to which memory is affected by alcohol. The study they conducted included a total of 48 participants age 18-34. Participants were assigned to one of four drug conditions: alcohol–alcohol, placebo–placebo, placebo–alcohol, and alcohol–placebo. Depending on their drug condition, participants were given either alcohol or placebo prior to word pairs being given, or preceding tests to measure their ability to remember the words. Participants were then given a list of 80 words presented in pairs. After participants saw each of the 80 pairs, they were instructed to perform an implicit stem completion test followed by an explicit cued recall task. These tests were used to measure how both implicit and explicit memory systems are affected by alcohol.
Duka et al. (2001) found that alcohol did not have a significant effect on the implicit recall task, or the cued recall task. Direct comparison between the groups that consumed alcohol and the groups that did not consume alcohol showed that alcohol given during retrieval diminished the ability for participants to give correct answers on a cued recall task with items from high association areas. However, there was no significant effect on the groups given alcohol in their ability to correctly answer items on an implicit stem completion task. From this, researchers suggest that alcohol effects processes that occur during retrieval more than those that occur during encodation. The conclusion that was made from this study was that alcohol affects explicit memory significantly, but it does not have a significant effect on implicit memory.
Whether alcohol affects memories dealing with future events, which are called prospective memories, has been studied by Paraskevaides et al. (2010). Their study was conducted in order to investigate an area of memory that had previously not been examined in alcohol research. They had a total of 32 participants that volunteered for the study. Each participant was screened and found to be healthy. Participants were assigned to be given alcohol in the alcohol group or placebo in the control group. After taking their drinks, some of the participants had their prospective memory manipulated by undergoing a behavior task wherein future events were simulated. Participants then had their episodic memory tested, using a source memory task and Tower of London task.
The results of gathered by Paraskevaides et al. (2001), were that future event simulation led to improved prospective memory performance for participants in the alcohol group. These improvements were made in areas that are typically deficient when individuals drink large amounts of alcohol. The researchers suggest that this interaction effect presented itself because certain information lapses from conscious awareness when individuals are under the influence of alcohol. On the other hand, when individuals acknowledge information with full attention, even when under the influence of alcohol, they are able to recall that information more effectively. The conclusion of the study was that future event simulation can reduce alcohol related deficits in prospective memory.
Alcohol leads to differences in the creation of intrusive memories, which are memories that persist within an individuals mind despite their attempts to have them stop. A study that was conducted by Bisby, Brewin, Leitz, & Curran (2009) showed that alcohol caused an inverted ‘U’ dose-response with a low dose of alcohol leading to increased intrusive memories and a high dose leading to decreased intrusions, but explicit memory performance after one week displays a linear dose-response of alcohol with recall and recognition performance decreasing with an increased dose. The effect of alcohol on memories that are spontaneous may indicate a dose-dependent disruption of two distinct memory systems involved with processing different components of traumatic events.
Thoma, Johann, Wähner, Juckel, & Daum (2008) found that the ability for recently detoxified alcohol-dependent subjects to recall information is significantly impaired along with their familiarity as detected through a verbal discrimination task. These findings were taken from a predominantly male sample, but could be generalized to the overall population. It has also been suggested that alcohol may impair processes of monitoring that are typically established upon encoding of memories, as determined through a study by Garfinkel et al. (2006). Alcohol appears to lead to decreased semantic activation as a result of alcohol consumption, which leads to a decline in false memories. Increased learning through repetition, which tends to lead to a decline in false memories with placebo, is counteracted with alcohol leading to decreased rates of rejections of false memories. Alcohol tends to lead to a decreased ability to consciously recollect factual information, but not to know responses to questions as found by Curran & Hildebrandt (1999). This shows that alcohol and depth of processing result in dissociative effects on recollective experience.
In a review of the literature pertaining to the acute effects of alcohol on memory, Mintzer (2007) came to the conclusion that there are still many open questions regarding the effects of alcohol on memory. Mintzer suggests that more hypothesis-driven research on alcohol’s effects on memory using behavioral and neuroimaging techniques would potentially increase the understanding of alcohol’s clinical implication and help aid in the clarification of basic cognitive functions and brain mechanisms.
The various effects of alcohol occur simultaneously at the physiological and psychological levels leading to a diverse range of effects. The frontal lobe of the brain is one of the most crucial features to examine when looking at the physiological implications of alcohol consumption. The morphological changes to the brain from alcohol intake may be what can explain the effects that it has on memory. Alcohol has an effect on various levels of memory, and there is an apparent dissociation between these levels as an effect of alcohol consumption.
This research is crucial to the understanding of both neurological structures and processes of memory. Further understanding of this subject area has clinical implications as well, and it could potentially result in an advancement of clinical programs for those recovering from alcohol dependencies. The studies that have been discussed throughout this paper have advanced psychological understanding of the effects of alcohol by showing an increasingly complex set of underlying principles and processes that occur when alcohol is consumed. Through this research, scientists now understand that alcohol acts on a diverse range of physiological and psychological mechanisms that combine to create rather distinct effects on multiple levels, and that it does not act in a clear linear fashion. This new level of understanding suggests that there are no simple effects of alcohol, or drugs in general, and that there are a tremendously large amount of variables to consider when undertaking the question of human complexity and variability.
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