Marijuana use is associated with a reorganized visual-attention network and cerebellar hypoactivation.
L Chang, R Yakupov, C Cloak, Thomas Ernst
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Sample size | 43 |
| Population | Chronic marijuana users (12 abstinent, 12 active) and 19 matched controls |
| Topics | Cannabis |
| Key findings | Active and abstinent marijuana users showed decreased activation in right prefrontal, medial and dorsal parietal, and medial cerebellar regions, but greater activation in various frontal, parietal, and occipital regions during visual-attention tasks, despite similar task performance. BOLD signals in right frontal and medial cerebellar regions normalized with abstinence duration, and active users showed greater activation than abstinent users, suggesting a neuroadaptive state. |
Abstract
Attention and memory deficits have been reported in heavy marijuana users, but these effects may be reversible after prolonged abstinence. It remains unclear whether the reversibility of these cognitive deficits indicates that chronic marijuana use does not alter cortical networks, or that such changes occur but the brain adapts to the drug-induced changes. Blood oxygenation-level dependent (BOLD) functional MRI (fMRI) was performed in 24 chronic marijuana users (12 abstinent and 12 active) and 19 age-, sex- and education-matched control subjects during a set of visual-attention tasks with graded levels of difficulty. Neuropsychological tests were also administered on each subject. The two marijuana user groups showed no significant difference in usage pattern (frequency or duration of use, age of first use, cumulative joints used, averaged >2000 joints) or estimated cumulative lifetime exposure of Delta-9-tetrahydrocannabinol (THC) (mean 168 +/- 45 versus 244 +/- 135 g). Despite similar task and cognitive test performance compared with control subjects, active and abstinent marijuana users showed decreased activation in the right prefrontal, medial and dorsal parietal, and medial cerebellar regions, but greater activation in various frontal, parietal and occipital brain regions during the visual-attention tasks (all with P < or = 0.001, corrected, cluster level). However, the BOLD signals in the right frontal and medial cerebellar regions normalized with duration of abstinence in the abstinent users. Active marijuana users, with positive urine tests for THC, showed greater activation in the frontal and medial cerebellar regions than abstinent marijuana users and greater usage of the reserve network (regions with load effect), suggesting a neuroadaptive state. Both earlier age of first use and greater estimated cumulative dose of THC exposure were related to lower BOLD signals in the right prefrontal region and medial cerebellum. The altered BOLD activation pattern in the attention network and hypoactivation of the cerebellum suggest neuroadaptive processes or alteration of brain development in chronic marijuana users. These changes also may be related to marijuana-induced alteration in resting cerebral blood volume/flow or downregulation of cannabinoid (CB1) receptors. The greater activation in the active compared with abstinent marijuana users demonstrates a neuroadaptive state in the setting of active marijuana use, while the long-term chronic effect of marijuana on the altered brain network may be reversible with prolonged abstinence.
Comparable studies
Other observational and cohort studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| High-potency cannabis and the risk of psychosis People with first episode of psychosis and healthy controls from the local population | 2009 | Case-control study | n = 454 |
| Ayahuasca-Assisted Therapy for Addiction: Results from a Preliminary Observational Study in Canada Rural aboriginal population | 2013 | Observational study | |
| Impaired cognitive performance in drug free users of recreational ecstasy (MDMA) Otherwise healthy young people | 2000 | Observational | |
| Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study Individuals from the general population in Germany aged 14-24 at baseline | 2011 | Observational cohort | n = 1,923 |
| Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: follow-up study of 535 incident cases Patients treated for cannabis-induced psychotic symptoms in Denmark between 1994 and... | 2005 | Observational cohort | n = 535 |
Citations in the library
Cited by 51
- Cannabis use before age 15 and subsequent executive functioning The British Journal of Psychiatry May 31, 2011
- The neuropsychopharmacology of cannabis: A review of human imaging studies Pharmacology & Therapeutics October 20, 2018
- Visual misperceptions and hallucinations in Parkinson's disease: Dysfunction of attentional control networks? Movement Disorders September 23, 2011
- Neuroimaging in cannabis use: a systematic review of the literature Psychological Medicine July 23, 2009
- The effect of cannabis on the brain: can it cause brain anomalies that lead to increased risk for schizophrenia? Current Opinion in Psychiatry March 1, 2008
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