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an essay on the link between marijuana and psychosis written by dahms 4 Dr. Alfredo Spagna on March 1, 2021

In 2012, a study was conducted to test the effects of long term marijuana abuse, on patients diagnosed with schizophrenia.  Specifically, this study looked to compare the cognitive functioning of schizophrenic patients with heavy cannabis use and those without (Lev-Ran, 2012).  Substance abuse is known to be much more common in patients who struggle from mental disorders, especially schizophrenia.  Most often, the drug of choice for these patients is cannabis (Koskinen, 2010).  This is likely due to the advertised calming effects of cannabidiol (CBD), a cannabinoid that makes up 40% of most marijuana plants.  However, another cannabinoid, tetrahydrocannabinol (THC), the main ingredient responsible for producing the ‘high’ sensation, is more likely to affect not only patients diagnosed with schizophrenia, but casual marijauna consumers as well (Lev-Ran, 2012).  The results of the study concluded that cannabis abusing patients tended to have attention deficit and reaction impairments, highlighting an impulsive response pattern within the sample group of patients.  However, the study also showed that patients who use cannabis tended to be able to function better on average, and experienced more mild symptoms.  This sets up the discussion of the overall ramifications and effects of cannabis usage amongst patients who suffer from schizophrenia    

Schizophrenia is a chronic mental disorder that impairs one's ability to interpret reality.  The most common symptoms of schizophrenia include hallucinations and irrational paranoia.  Symptoms can range from mild to severe, but tend to be very impairing to one's daily life (Torres, 2020).  Generally, patients diagnosed with schizophrenia need to receive lifelong treatment.  If the treatment begins early enough, before patients enter the late stages of complications, then their long-term symptoms can be drastically reduced (Silverstein, 2013).  The exact cause of schizophrenia is unknown, but it is hypothesized that early onset drug use could be a potential trigger for the illness in high risk patients.  This is hypothesized to occur due to a disruption of dopaminergic pathways due to repeated drug administration (Ryan, 2020).  Treatments for schizophrenia can vary from patient to patient but generally the treatment is life-long and only results in a moderation of the symptoms, rather than eradication.  Some believe that low-THC cannabis could potentially be used in moderation to treat patients suffering from schizophrenia, helping them by alleviating various anxiety driven symptoms.           

In the aforementioned 2012 study, the aim was generally to test the effects of long-term cannabis abuse, on schizophrenic patients, and healthy controls.  The overall sample size of the participants was 43, with 28 participants diagnosed with schizophrenia and 15 listed as healthy controls.  Amongst the 28 schizophrenic patients 12 of them were labeled as cannabis dependent, the rest reported little-to no use with the drug.  4 of the 15 healthy controls self reported as mild-to-little cannabis users.  This sampling stood out to me mainly because of the lack of cannabis users present in the control group.  A more thorough and specific comparison of the effects could have been achieved if there were more heavy cannabis using controls to cross reference the data with.  DSM-IV-TR criteria was used to diagnose the schizophrenic patients as well as the cannabis dependent patients (Lev-Ran, 2012).  For both groups, other substance usage was reported to be under the threshold of 5 times or less throughout their lifetime, with none of these instances occurring within a year of the study.  Specifically, the inquired about substances included alcohol, cocaine, psilocybin, opioids and methamphetamines.  Due to the functions of the tests at hand, applicants who suffered from Intellectual Disability, Down Syndrome, and color-blindness were excluded from the study.  These extremely specific parameters are most likely why such a small sample size was provided for this study.  

Prior to the neurocognitive assessment, each subject was re-screened within the study to confirm their schizophrenic and or healthy diagnosis.  For the healthy controls, they were put through a follow up interview and survey that was again compared against DSM-IV-TR criteria to ensure that they were not suffering from any other mental disorder and or substance abuse.  All schizophrenic patients were put through a new test utilizing the Positive and Negative Symptoms Scale (PANSS) to confirm their diagnosis, as well as a functional assessment known as the Global Assessment of Functioning (GAF), in order to compare the severity levels of symptoms within each patient (Lev-Ran, 2012).  The results of these tests were also used in the overall statistics of the study for those patients who passed this second screening checkpoint.  All of the subjects were also tested for drug use the day of the neurocognitive assessments.

Following this multiple tests were performed to observe each subject's basic neuro-motor abilities, this included attention, visual memory, spatial memory, and executive functioning (Lev-Ran, 2012).  The tests were presented to each patient in a randomized manner.  The researchers of this study tended to focus on more cognitive abilities, rather than behavior.  This was likely to maintain consistency of participation throughout the entirety of the study.  However it would be interesting to test other neurocognitive behaviors such as learning, sleeping, and external motor agility; though it would likely require more time and resources to accurately study these behaviors.  This could help to add some additional context to the overall implications of usage in regards to everyday behavior.  After the conclusion of the tests within the study, the results from the schizophrenic group were compared against the healthy controls, using an independent t-test, as well as a Chi2 test.  These same statistical tests were used to also compare the Schizophrenic with cannabis dependent group (SCH+CAN) to the schizophrenic without cannabis dependent group (SCH-CAN).  The purpose of using these tests is to identify significant differences between the groups at a standard alpha value of 0.05.  The statistical analysis of this study was fairly standard yet, the limited sample size may cause staggered or unclear results regarding the averages and p-value of each metric.  

The results of the study predictably showed several distinct differences in the cognitive abilities of the schizophrenia patients, compared to the control group.  These figures suggest strong impairment in visual and spatial memory of the schizophrenia group.  Though this outcome was expected, it would have been of benefit to the study to provide comparison between schizophrenic cannabis users and healthy cannabis users.  In addition to the previously mentioned finding there was also heavy evidence showing impairment of the basic executive function of schizophrenia subjects, compared to their control counterparts (Lev-Ran, 2012).  This gap in ability reveals the specific deficits between schizophrenic patients and neurotypical individuals.   

Within the SCH+CAN group and the SCH-CAN group the results appeared to be much more mixed.  There was a significant difference found in the results of the GAF, revealing that the SCH+CAN group actually appeared to have better functioning than the SCH-CAN Group (Lev-Ran, 2012).  This finding was not necessarily unexpected, but rather surprising due to the inhibitory nature that cannabis posed on the other sections of the tests.  In addition, within the negative symptoms test, there was no significant difference found between the two groups, but interestingly, there was a minor trend suggesting the SCH+CAN participants suffered less negative symptoms.  Negative symptoms are defined as symptoms that essentially take away from a patient's ability to function.  For schizophrenia specifically, these symptoms can include loss of speech, apathy, motivation and social abilities.  Positive symptoms on the other hand tended to be fairly consistent through both groups.  In schizophrenia patients these symptoms can include hallucinations, false stimuli, and erratic movement.  Outside of the PANSS testing, there were other significant results that separated the two groups within the cognitive testing portion of the assessment.  For instance, on average, SCH+CAN participants showed significantly less ability to problem solve, critically think, and identify target responses within the given time periods of their tests (Lev-Ran, 2012).  SCH+CAN participants also tended to make more errors within these cognitive agility tests, but this figure was not statistically significant.  However, there was a trend in the type of errors committed by the SCH+CAN group which is usually seen to be a null error, meaning they failed to identify various answers or stimuli, rather than answering incorrectly.  Along with this, SCH+CAN were also more likely to produce false positive reactions to the attention portion of the assessment.  Both of these revelations suggest that patients of this group held a larger attention deficit than those of the SCH-CAN group.  Though this difference in response ability was observed between the two groups, this does not necessarily denote a correlation.  However, some potential reasons for this result may be due to the long-term effects of the psychoactive ingredient of marijauna, THC.  With heavy, sustained use, THC is known to alter the chemistry of the brain in healthy individuals (Keeley, 2015).  This same effect could likely produce an alternative cognitive function within schizophrenia patients.    

Overall, the comparison between schizophrenia patients and health controls was on point with other reports and studies, as well as the general hypothesis.  Controls tended to score higher on average in every cognitive and functional test provided.  The intention of this study was mainly to find the specific differences between the SCH+CAN and SCH-CAN groups, which was revealed by comparing their cognitive testing results.  Schizophrenia patients that were also diagnosed with cannabis dependency were more susceptible to making null errors and detecting less stimuli in the continuous performance tests, this result was mainly attributed to the hypothesized attention deficit that was present with cannabis users (Lev-Ran, 2012).  SCH+CAN patients also significantly underperformed in the spatial memory tests, as well as the critical thinking assessments that were timed.  In regards to overall functioning, surprisingly, SCH+CAN patients tended to score higher in this portion of the assessment.  This suggests that generally, schizophrenia patients that use cannabis or have used cannabis may have milder symptoms and or show higher levels of functioning (Lev-Ran, 2012).  This result could be derived from a plethora of reasons including utilizing higher level functioning frequently to obtain cannabis regularly, or even simply just positive effects that cannabis may have on the daily functions of schizophrenia patients.  An additional study and future replications would be necessary to derive the exact cause of this significant event.

Despite the hypothesized results being produced on average, there were several limitations in regards to the overall methods and samples used within this study.  For instance the lack of cannabis-dependent healthy controls within the sample, restricted researches from cross comparing results between the respective sub-groups.  Moreover, another limitation is the potential difference in effects of cannabis depending on the strain and CBD to THC ratio, since the usage was self reported and used external to the experience in the past.  Lastly, since the results were compared cross-sectionally, it was impossible to identify a causal relationship between cannabis dependence and higher cognitive functioning within the schizophrenia patients.  

In short, one of the most elementary takeaways from this study is that cannabis use certainly has a variety of effects among patients who suffer from schizophrenia (Lev-Ran, 2012).  This study played an important role in determining whether or not cannabis could potentially be used to treat patients that are diagnosed with schizophrenia.  In regards to the aforementioned study it appears that there is generally no specific benefit or disadvantage to these patients using cannabis, as it appears to affect each person differently, despite the minor trends observed.  

A replication of this study would benefit from the additional variables of CBD ratio, as well as quantity of marijauna consumption.  CBD is known as the calming cannabinoid that resides in marijauna.  In fact, most states across the country today actually allow for legal sale and consumption of CBD products in all stores, due to the fact that it does not technically inhibit the mind or change one's functional mindstate.  THC on the other hand is the main psychoactive ingredient within marijauna.  It’s effects are capable of altering the mindstate of the user, hence its illegality in the majority of states today.  Regarding Lev-Ran’s study, I would hypothesize that the long-term effects of CBD synthesis were shown in the GAF tests, which showed that SCH+CAN patients significantly scored higher on average in their daily functioning tasks.  On the contrary,  the results of the cognitive tests may reveal the long-term effects of THC on the brain regarding spatial memory and critical thinking.  To test these claims this experiment could be replicated between control groups and schizophrenia patients, but this time while either under the influence of cannabis or not, of course at the consent of each participant. 

The breakdown of groups for a study like this would be similar to Lev-Ryan’s, but with a few additional subgroups.  For instance, there would still be SCH+CAN and SCH-CAN but within the cannabis using group there would be a separation between CBD dominant strains and THC dominant strains.  These subgroups would be mirrored for the controls as well.  In total this would provide 6 total groups: SCH+CBD, SCH+THC, SCH-CAN, CONTROL+CBD, CONTROL+THC, and CONTROL-CAN.  A larger sample size would also benefit the overall validity and assessment of the patients as a whole.  These additional groups would allow for much more cross sectional comparison, allowing researchers to zero in on a more direct causal distinction for the impending results.  Since the participants would be performing these tasks while under the influence of the drug, a placebo would need to be administered as well to the -CAN groups in order to ensure each participant believes they are on a level playing field.  This revamped study would provide more context as to precisely how cannabis use affects patients diagnosed with schizophrenia, as well as healthy humans as well.               

One thing that is still up in the air, is the effect cannabis can have prior to psychotic symptoms arriving in patients.  Some researchers even hypothesize that cannabis can be a potential trigger for these symptoms, regardless if the user is diagnosed with schizophrenia or not (Ryan, 2020).  In general, the exact derivation of schizophrenia is unknown, but it is hypothesized to be from a variety of reasons including genetics, environmental circumstances, and neuro-alterations.  One interesting finding from an alternative study showed that within a sample size of 264 schizophrenia patients over 38% reported to use cannabis prior to the age of 16 (Ryan, 2020).  This figure was significantly higher than the 22% of control participants of an equal sample size who responded to the same question.  Not only this but also this study showed that these patients diagnosed with schizophrenia were more likely to have a history of childhood trauma, as well as family related drug abuse problems.  However, when adjusting for covariates the researchers concluded that adolescent cannabis use was not supported by the results presented from the study.  In fact, it was seen that adolescent cigarette use was potentially more independently prevalent in schizophrenia patients (Ryan, 2020).



References:
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