This study was an observational case-control follow-up study done in a rehabilitation centre in the state of Andhra Pradesh. Sampling was done using the purposive sampling method. The study comprised two groups of subjects. Those were 50 young people between the ages group 18–25 years with active cannabis use (group A) who got admitted to the rehabilitation centre and a comparison group consisting of 50 college students pursuing their graduation with no history of cannabis use (group B). Smoking was the sole method of consumption of cannabis in all these 50 patients. The Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (SCID-5) was used to diagnose cannabis use disorder, and it was confirmed by urine drug screening.
Written informed consent was taken from the subjects from both the study and control groups and from the caregivers wherever required. Subjects with a history of head injury and seizures, those who were suffering from substance-induced psychosis or any other psychological disorders, or those who were already taking treatment for their substance use were excluded from the study. After obtaining the Indlas VIMHANS Hospital institutional ethics committee’s approval, the study was conducted from June 2021 to December 2021.
A semi-structured pro forma was used to collect the socio-demographic data. The Montreal Cognitive Assessment (MoCA) test was used to assess cognitive functioning. It was developed by Dr. Ziad Nasreddine and colleagues in 2005 for the assessment of cognitive functions . The MoCA test consists of 13 items measuring seven cognitive domains: executive functioning; visuospatial abilities; attention, concentration, and working memory; language; abstract reasoning; memory; and orientation with a maximum score of 30. It is a one-page test that can be administered in 10 min. Its reliability was adequate, with a coefficient alpha of 0.75 , and its sensitivity and specificity in detecting mild cognitive impairment were found to be 86% . The following ranges may be used to grade the severity of cognitive impairment: 18–25 = mild cognitive impairment, 10–17= moderate cognitive impairment, and less than 10 = severe cognitive impairment. The study was done in 2 steps.
The cognitive functioning of subjects from group A was assessed by using Montreal Cognitive Assessment (MoCA) test after an initial period of 1 week of abstinence. These scores were compared with the MoCA scores of group B.
We have chosen this 1-week abstinence period, as assessing cognitive functioning under cannabis intoxication and immediate withdrawal period may not give proper test results due to the acute effects of cannabis on attention and concentration.
The cognitive functioning of patients from group A was reassessed after the completion of 3 months of treatment in our rehabilitation centre by repeating the MoCA test. The patients were completely abstinent from any kind of psychoactive substance during this period. All these patients attended a daily routine programme of ground activities for 60 min, breathing exercises for 10 min, Jacobson’s progressive muscle relaxation (JPMR) exercise for 20 min, yoga and meditation for 30 min, and daily counselling sessions. JPMR is a non-pharmacological method of relaxation, teaching the patients to monitor the tension in specific muscle groups by first tensing and then relaxing each muscle group. It is widely used to reduce the anxiety and increase self-esteem and thus helps patients in dealing with stressful conditions more confidently. No special medications were given, or cognitive remedial techniques were taught to improve their cognitive functioning.
The effect of cannabis use on cognitive functioning was assessed by comparing scores of group A (at 1st week of treatment) and group B.
The effect of abstinence from cannabis use on cognitive functioning was assessed by comparing scores of group A in the 1st week and after the 3rd month.
Data entry and analysis were performed using Microsoft Excel (2019) and MedCalc version 20.109 (Ostend, Belgium).
Continuous variables were reported as means with standard deviations (SD), and categorical variables were reported as numbers with the percentage of the total.
Karl Pearson’s correlation coefficient was used to calculate the relationship between duration, the quantity of cannabis use, and the initial MoCA score of cannabis users.
The Z-test of difference between two means was used to compare mean scores of MoCA between cannabis use and nonuser groups. Paired t-test was used to compare the initial MoCA score with the score after 3 months of abstinence from cannabis.
For all analyses, the probability level considered to indicate statistical significance was set at P < 0.05.