Elsevier

Drug and Alcohol Dependence

Volume 178, 1 September 2017, Pages 215-222
Drug and Alcohol Dependence

Full length article
History of cannabis use is associated with altered gait

https://doi.org/10.1016/j.drugalcdep.2017.05.017Get rights and content

Highlights

  • Cannabis users exhibit increased angular velocity of the knee during walking gait.

  • Cannabis users exhibit reduced shoulder flexion during walking gait.

  • Gait changes in cannabis users are not of a magnitude that is clinically detectable.

Abstract

Background

Despite evidence that cannabinoid receptors are located in movement-related brain regions (e.g., basal ganglia, cerebral cortex, and cerebellum), and that chronic cannabis use is associated with structural and functional brain changes, little is known about the long-term effect of cannabis use on human movement. The aim of the current study was to investigate balance and walking gait in adults with a history of cannabis use. We hypothesised that cannabis use is associated with subtle changes in gait and balance that are insufficient in magnitude for detection in a clinical setting.

Methods

Cannabis users (n = 22, 24 ± 6 years) and non-drug using controls (n = 22, 25 ± 8 years) completed screening tests, a gait and balance test (with a motion capture system and in-built force platforms), and a clinical neurological examination of movement.

Results

Compared to controls, cannabis users exhibited significantly greater peak angular velocity of the knee (396 ± 30 versus 426 ± 50°/second, P = 0.039), greater peak elbow flexion (53 ± 12 versus 57 ± 7°, P = 0.038) and elbow range of motion (33 ± 13 versus 36 ± 10°, P = 0.044), and reduced shoulder flexion (41 ± 19 versus 26 ± 16°, P = 0.007) during walking gait. However, balance and neurological parameters did not significantly differ between the groups.

Conclusions

The results suggest that history of cannabis use is associated with long-lasting changes in open-chain elements of walking gait, but the magnitude of change is not clinically detectable. Further research is required to investigate if the subtle gait changes observed in this population become more apparent with aging and increased cannabis use.

Introduction

Approximately 3.9% of the world’s adult population have used cannabis, with the Oceania region having the highest prevalence of use (United Nations Office on Drugs and Crime, 2014). In Australia, 35% of individuals aged 14 years and over have tried cannabis at least once, with the estimated age of cannabis initiation at 16.7 years (Australian Institute of Health and Welfare, 2014).

The major psychoactive component of cannabis, Δ9-tetrahydrocannabinol (THC), binds to cannabinoid-type 1 (CB1) receptors that are widely distributed throughout the central nervous system (Hirvonen et al., 2012). High densities of CB1 receptors are found in the hippocampus, amygdala, and movement-related brain regions, including the basal ganglia, cerebellum, and cerebral cortex (Oliviero et al., 2012). CB1 receptors are primarily located on the presynaptic membrane (Hirvonen et al., 2012) and activation can inhibit neurotransmitter release (Schlicker and Kathmann, 2001).

Cannabis intoxication results in acute motor deficits, including changes in balance (Ramaekers et al., 2006). An acute concentration-dependent disturbance in balance has been observed, with increasing levels of THC resulting in increased body sway (Kiplinger et al., 1971, Zuurman et al., 2008), possibly due to activation of CB1 receptors in movement-related brain regions. However, it is not known if cannabis use is associated with long-lasting disturbances in functional movement tasks such as balance and walking gait.

There are several lines of evidence to suggest that cannabis use may have a long-lasting effect on both gait and balance. There is a high density of CB1 receptors in movement-related brain regions (Takahashi and Linden, 2000) and within the dorsal and ventral horns of the spinal cord (Ong and Mackie, 1999). Animal studies suggest that cortical neurons exhibit a dose-dependent widening of the synaptic cleft and development of nuclear inclusion bodies in response to THC administration (Harper et al., 1977, Heath et al., 1980). Chronic cannabis use in humans is also associated with decreased white matter density in the left parietal lobe (Matochik et al., 2005) and long-term changes in cognitive functions (e.g., memory and executive functioning) (Solowij and Pesa, 2011). Therefore, it is conceivable that functional changes in the motor system may occur.

The aim of the current study was to investigate gait and balance in individuals with a history of cannabis use. We hypothesised that cannabis users would exhibit subtle features of ataxic gait and increased postural sway during quiet standing compared to non-drug users. The hypotheses were based on: (i) subjective observations of gait and balance abnormalities in individuals dependent on alcohol and either cannabis, stimulants, and/or opiates (Fein et al., 2012); and (ii) pathological and pathophysiological changes observed in the brains of cannabis users (Harper et al., 1977, Heath et al., 1980, Matochik et al., 2005). It was also hypothesised that disturbances in gait and balance observed in a laboratory setting would be too small to detect in a clinical setting. This hypothesis was based on the lack of reports of clinical movement dysfunction in cannabis users. The results of the current study advance knowledge of the long-lasting consequences of cannabis use in humans.

Section snippets

Subjects and screening

Two groups of adults aged 18–49 years participated in the study: 22 subjects with no history of illicit drug use (‘control group’) and 22 subjects with a history of cannabis use (>6 occasions) but no history of illicit stimulant or opioid use (‘cannabis group’). All experimental procedures were approved by the Southern Adelaide Clinical Human Research Ethics Committee and the University of South Australia Human Research Ethics Committee. The experimental procedures were conducted in accordance

Subject characteristics

The groups were matched for age and symptoms of depression (Table 1). Lifetime use of alcohol was significantly greater in the cannabis group than in controls (P < 0.001). Lifetime use of tobacco also tended to be greater in the cannabis group, but did not reach statistical significance.

Table 2 shows single-subject and group data for lifetime use of cannabis. Fifty per cent of the sample had used cannabis on >50 occasions and the average duration of abstinence from cannabis was 0.7 ± 1.2 years

Discussion

The aim of the study was to investigate the long-lasting effect of cannabis use on gait and balance in healthy adults. The results of the study suggest that individuals with a history of cannabis use exhibit subtle changes in gait, primarily in open-chain components of walking gait, but not balance.

Individuals with a history of cannabis use exhibited abnormalities in the lower limb during gait. The velocity of the knee during the swing phase of gait was significantly greater (7%) in cannabis

Role of funding source

The funding sources had no involvement in the i) study design, ii) collection, analysis, and interpretation of the data, and iii) writing and submission of the article for publication.

Contributors

GT, JMW, DT, RAW, and APV contributed to study concept and design. VPD, DT, GT, and RAW were involved in acquisition of the data. VPD, GT, JMW, DT, RAW, and APV were involved in analysis and interpretation of the data. VPD, DT, and GT were involved in drafting of the manuscript. VPD, GT, JMW, DT, RAW, and APV contributed to critical revision of the manuscript for important intellectual content and approved the final manuscript before submission.

Conflict of interest

No conflict declared.

Acknowledgements

The work was supported by the National Health and Medical Research Council of Australia (GT held a Career Development Award ID 627003, APV holds a Career Development Fellowship ID 1082910), Australian Government (VPD held an Australian Postgraduate Award), and the University of South Australia.

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