Effects of Marijuana on Memory of Long-Term Users

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Table of Contents

Specific Aims
Background
Significance
Proposed Study
Budget Justification
References

Specific Aims

Today, marijuana is one of the most widespread drugs that are used in recreational issues and illegally. Even though many people consider it to be harmless, marijuana may cause significant changes in a person’s brain, leading to memory loss, decreased speed of thinking, and other neurocognitive alterations. In the recent study, Sagie, Eliasi, Livneh, Bart, and Monovich (2013) discovered that cannabinoids have an adverse impact on both short- and long-term memory.

While the former is reversible and can be enhanced in the course of treatment, the latter is regarded as permanent as it cannot be restored. The authors state that their findings are consistent with the previous research, yet there are many issues that remain unexplored, which is primarily associated with differences in marijuana users’ dosage, endogenous brain compensation, frequency, and other characteristics (Sagie et al., 2013). More to the point, psychotic attacks and sclerosis are also suggested as consequences of long-term marijuana consumption.

The pivotal aim of the proposed study is to evaluate the impact of marijuana use on long-term memory of respondents. The existing evidence resorts to the fact that continuous marijuana use may cause the development of false memories decreased learning ability, and other memory problems. In this regard, there is a need to experimentally understand the effects of marijuana and provide recommendations to avoid serious negative consequences.

It is expected that results of the study would contribute to understanding the given problem, including its severity, prevalence, and potential damage to memory. The specific objectives of this study are to test the stated hypotheses based on clinical experiments and provide relevant recommendations on the use of marijuana with regard to memory issues.

Background

The neurocognitive impact of cannabis has been explored by many scholars who present heterogeneous results. While some of them state that long-term use of marijuana in appropriate dosage and under monitoring can be beneficial, others argue that it leads to sclerosis, psychotic deteriorations, and impaired verbal memory (Cohen et al., 2017). Wise (2016) notes that long-term marijuana use is related to impaired verbal memory, but it is not linked to other cognitive functions.

The 25 year study shows that the cumulative effect of marijuana use is closely associated with worsening verbal memory: “with each five years, it was 0.13 standardized units lower than in those who had never used it (95% confidence interval –0.24 to 0.02; P=0.02 ) (Wise, 2016, para. 6). These results are consistent with the previous research; therefore, the author suggests continuing studies with multiple assessments that should also focus on other functional outcomes.

The adverse impact of marijuana after the abstinent syndrome refers to significant changes in prefrontal and hippocampus areas that are responsible for the cognitive function and memory (Busquets-Garcia et al., 2018; Sandler, Fetterhoff, Hampson, Deadwyler, & Marmarelis, 2017). Ganzer, Bröning, Kraft, Sack, and Thomasius (2016) conducted the literature review and revealed negative neurocognitive changes occurred in abstinence. In particular, episodic memory failures were more frequent is adolescents compared to adults, which can be explained by a more intensive neural activity and growing connections between neurons.

Several studies examined by Ganzer et al. (2016) pinpoint to macrostructural brain alterations that may cause short-term memory losses: problems with encoding, storing, and retrieving mechanisms of memory. Although the majority of the reviewed studies illustrate some destructive impact of marijuana, others provide no specific effects linked with worsening memory.

Memory problems often contain such conditions as sclerosis, depression, psychotic states, et cetera. It seems important to discuss the studies that examine long-term marijuana exposure with regard to these conditions in order to understand the links between them. According to Brenton et al. (2018), in marijuana-using adult multiple sclerosis (MS), the deterioration of memory is even more pronounced. Along with the studies that provide the corresponding results, participants also present their perceptions that are associated with problems with focus and memory.

Even though the majority of the scholarly articles present adverse effects of marijuana, others show the opposite findings. In their turn, Kindred et al. (2017) also studied people with sclerosis and Parkinson’s disease who used cannabis for both recreational and non-medical purposes. Based on an anonymous web-based survey, 595 participants were interviewed, while 59 percent of them reported that cannabis use allowed decreasing prescription drug use due to its high efficiency (6.4 (SD 1.8) on a scale from 0 to 7) (Kindred et al., 2017, p. 103).

In particular, it is emphasized that cannabis exposure was useful to handle obesity, inability in mood, and memory problems. On the contrary to the studies that report about the negative impact of marijuana, the mentioned one provides positive results. Nevertheless, the subsequent investigations are needed in order to ensure detailed understanding of connections between sclerosis, Parkinson’s disease, and cannabis exposure.

The interaction between depression and marijuana dependence promotes memory decrements. With the use of the California Verbal Learning Test-Second Edition (CVLT-II), both depressed and non-depressed marijuana users were examined through the clinician-rated Hamilton Depression Rating Scale (HAM-D) as well as self-rated Beck Depression Inventory (BDI-II) (Roebke, Vadhan, Brooks, & Levin, 2014). Both groups showed the reduced CVLT-II, but no other significant differences were detected. In other words, the described study is consistent with the one conducted by Kindred et al. (2017) as both of them revealed no decrements in verbal learning of long-term marijuana users.

The onset of false memories is the other unfavorable consequence of marijuana consumption that is reported by several studies. For example, Riba et al. (2015) discovered that false memories may occur in heavy marijuana smoker even if they quit it months ago.

According to the verified hypothesis of this study, adolescents who used to smoke marijuana for years are more likely to develop memory-related diseases in adulthood compared to those who started taking it being adults. A set of memory tests offered to the participants of the study was performed by the above group 18 percent worse (Riba et al., 2015). This means that teenagers are at higher risk of memory problems, which makes this issue more alarming.

At the same time, the similar results may be viewed in the article by Setién-Suero et al. (2018), who focused on psychotic marijuana users: their condition, namely, verbal memory significantly enhanced after their quitted. The paramount difference between the latter two studies lies in the fact that they present opposite results regarding the age of marijuana use onset. The hypothesis for the potential study may be formulated as follows: long-term marijuana users are more likely to develop memory problems compared to short-term users.

Significance

It should be stressed that several concerns identify the need for further research studies. First of all, many studies explore the short-term impact of marijuana exposure on one’s memory changes, yet no specific determination of how long a person should take this drug to call it long-term was clarified. Second, the other question is associated with causal relationships, namely, causes and effects.

Some scholars claim that brain abnormalities may presuppose the onset of memory alterations during chronic marijuana use, and others assume that it is marijuana that causes brain structure impairment (Ganzer et al., 2016). In other words, it is still unclear what exactly makes users’ memory deteriorate in a long-term period. In this regard, future studies should take the mentioned points into account to eliminate the existing limitations to come up with relevant conclusions regarding the problem of marijuana consumption.

In the view of recent decriminalization of marijuana in several states and its extensive use in recreational means, it is possible to expect that the drug abuse and long-term consumption will increase (Bossong et al., 2012; Goodman & Packard, (2015).

Considering that marijuana exposure may only benefit their health, many people are likely to take it for various reasons, being unaware of potential consequences. Therefore, it is essential to conduct the proposed study and increase awareness of populations, especially those who are at risk of memory problems (Oomen, van Hell, & Bossong, 2018). If the proposed aims would be accomplished, both recreational and non-medical marijuana consumption may be reconsidered by health policymakers, care providers, patients, and people who use it on their own. It is expected that better knowledge of long-term marijuana use impact on memory may aid early diagnosis of memory-related problems.

Proposed Study

Participants

Eighty adult participants – long-term users of marijuana – will be recruited and then divided into two categories. Twenty members of the first group will receive a placebo, and the other half of this group will be given marijuana without tetrahydrocannabinol (THC). The second group will be asked to use the real marijuana provided by the researchers in order to avoid any side effects that can be caused by other sources. The participants will be recruited randomly from the A hospital, and approved for the study based on memory tests.

Prior to the study, all potential participants will receive informed consent forms and the document explaining the aims and procedures of the experiment. It will be clarified in advance that the participation is voluntary, and every respondent may quit the study at any time. In addition, the study will provide payment for participants, and they will benefit from the results of the study by obtaining detailed understanding of marijuana impact on their memory. No deception of any kind will be used to ensure safety, respect, and comfort of participants.

Procedures

The proposed longitudinal mixed method study will be conducted in inpatient setting at A hospital, where every participant will be met at person and given necessary documents. The study will start with providing working memory and long-term memory tests, the results of which will be compared and contrasted to post-study tests (Smith et al., 2017). The intervention group will receive marijuana daily, while the control group will be asked to use it in a similar manner.

The photo recognition test will be utilized to examine how participants will remember the persons they will see before and after the experiment. The intervention will take three months to evaluate the impact of marijuana exposure on both explicit and implicit memory of participants. The data will be collected from participants through self-reports and tests in the process of the intervention and after it.

Hypotheses and Analysis

The hypotheses for the proposed research are:

Long-term marijuana consumption contributes to impaired memory, false memories, and verbal memory deterioration.
People with Parkinson’s disease and sclerosis using marijuana in a long-term period are likely to encounter with worsening of their diseases.

The intervention group is likely to show worsening memory compared to the control group. The first signs of memory deterioration are likely to be noted, including false memories, sclerosis onset, and so on. The scores of both groups will be compared based on ANOVA or SPSS software; the analysis of variance will consist in determining the ratio of systematic (intergroup) variance to random (intragroup) variance in the measured data. The purpose of data analysis will be to check the statistical significance of the difference between the means by splitting the total variance into parts, one of which is focused on a random error, and the second is related to the difference in mean values.

Budget Justification

Funding is requested for the instructor and research assistant, who will be responsible for conducting the study, including recruitment of participants, monitoring the intervention, and analyzing results. Travel funding will be required for principal attendance at a national meeting to provide the study results to the public. Each participant will be offered pay of $50 in order to reimburse his or her time and contribution. Also, Apple Laptop computer (15” with retina display, 2.8 GHz processor, 1 TB hard drive) will be required to collect, store, and process data. Quality of Life scale and office supplies are requested as well. The detailed budget planning can be viewed in the figure below.

References

Bossong, M. G., Jager, G., van Hell, H. H., Zuurman, L., Jansma, J. M., Mehta, M. A.,… Ramsey, N. F. (2012). Effects of Δ9-tetrahydrocannabinol administration on human encoding and recall memory function: A pharmacological fMRI study. Journal of Cognitive Neuroscience, 24(3), 588-599.

Brenton, J. N., Schreiner, T., Karoscik, K., Richter, M., Ferrante, S., Waldman, A., & Banwell, B. (2018). Attitudes, perceptions, and use of marijuana in youth with multiple sclerosis. Journal of Neurology, 265(2), 417-423.

Busquets-Garcia, A., Gomis-González, M., Salgado-Mendialdúa, V., Galera-López, L., Puighermanal, E., Martín-García, E.,… Ozaita, A. (2018). Hippocampal protein Kinase C signaling mediates the short-term memory impairment induced by Delta9-Tetrahydrocannabinol. Neuropsychopharmacology, 43(5), 1021-1031.

Cohen, K., Kapitány-Fövény, M., Mama, Y., Arieli, M., Rosca, P., Demetrovics, Z., & Weinstein, A. (2017). The effects of synthetic cannabinoids on executive function. Psychopharmacology, 234(7), 1121-1134.

Ganzer, F., Bröning, S., Kraft, S., Sack, P. M., & Thomasius, R. (2016). Weighing the evidence: A systematic review on long-term neurocognitive effects of cannabis use in abstinent adolescents and adults. Neuropsychology Review, 26(2), 186-222.

Goodman, J., & Packard, M. G. (2015). The influence of cannabinoids on learning and memory processes of the dorsal striatum. Neurobiology of Learning and Memory, 125, 1-14.

Kindred, J. H., Li, K., Ketelhut, N. B., Proessl, F., Fling, B. W., Honce, J. M.,… Rudroff, T. (2017). Cannabis use in people with Parkinson’s disease and multiple sclerosis: A web-based investigation. Complementary Therapies in Medicine, 33, 99-104.

Oomen, P. P., van Hell, H. H., & Bossong, M. G. (2018). The acute effects of cannabis on human executive function. Behavioural Pharmacology, 29(7), 605-616.

Riba, J., Valle, M., Sampedro, F., Rodriguez-Pujadas, A., Martinez-Horta, S., Kulisevsky, J., & Rodriguez-Fornells, A. (2015). Telling true from false: Cannabis users show increased susceptibility to false memories. Molecular Psychiatry, 20(6), 772-777.

Roebke, P. V., Vadhan, N. P., Brooks, D. J., & Levin, F. R. (2014). Verbal learning in marijuana users seeking treatment: A comparison between depressed and non-depressed samples. The American Journal of Drug and Alcohol Abuse, 40(4), 274-279.

Sagie, S., Eliasi, Y., Livneh, I., Bart, Y., & Monovich, E. (2013). Short-and long-term effects of cannabinoids on memory, cognition and mental illness. Harefuah, 152(12), 737-741.

Sandler, R. A., Fetterhoff, D., Hampson, R. E., Deadwyler, S. A., & Marmarelis, V. Z. (2017). Cannabinoids disrupt memory encoding by functionally isolating hippocampal CA1 from CA3. PLoS Computational Biology, 13(7), 1-16.

Setién-Suero, E., Martínez-García, O., de la Foz, V. O. G., Vázquez-Bourgon, J., Correa-Ghisays, P., Ferro, A.,… Ayesa-Arriola, R. (2018). Age of onset of cannabis use and cognitive function in first-episode non-affective psychosis patients: Outcome at three-year follow-up. Schizophrenia Research, 1-8. Web.

Smith, J. L., De Blasio, F. M., Iredale, J. M., Matthews, A. J., Bruno, R., Dwyer, M.,… Mattick, R. P. (2017). Verbal learning and memory in cannabis and alcohol users: An event-related potential investigation. Frontiers in Psychology, 8, 1-18.

Wise, J. (2016). Long term marijuana use is linked to impaired verbal memory. British Medical Journal (Online), 352. Web.

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