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Clinical Trial
. 2013;8(1):e53127.
doi: 10.1371/journal.pone.0053127. Epub 2013 Jan 2.

Psychomotor function in chronic daily Cannabis smokers during sustained abstinence

Wendy M Bosker  1 , Erin L Karschner, Dayong Lee, Robert S Goodwin, Jussi Hirvonen, Robert B Innis, Eef L Theunissen, Kim P C Kuypers, Marilyn A Huestis, Johannes G Ramaekers
Affiliations
Clinical Trial

Psychomotor function in chronic daily Cannabis smokers during sustained abstinence

Wendy M Bosker et al. PLoS One. 2013.

Abstract

Background: The present study assessed psychomotor function in chronic, daily cannabis smokers during 3 weeks continuously monitored abstinence on a secure research unit. We hypothesized that psychomotor performance would improve during abstinence of chronic, daily cannabis smokers.

Methodology/principal findings: Performance on the critical tracking (CTT) and divided attention (DAT) tasks was assessed in 19 male chronic, daily cannabis smokers at baseline and after 8, 14-16 and 21-23 days of continuously monitored abstinence. Psychomotor performance was compared to a control group of non-intoxicated occasional drug users. Critical frequency (λ(c)) of the CTT and tracking error and control losses of the DAT were the primary outcome measures. Results showed that chronic cannabis smokers' performance on the CTT (p<0.001) and the DAT (p<0.001) was impaired during baseline relative to the comparison group. Psychomotor performance in the chronic cannabis smokers improved over 3 weeks of abstinence, but did not recover to equivalent control group performance.

Conclusions/significance: Sustained cannabis abstinence moderately improved critical tracking and divided attention performance in chronic, daily cannabis smokers, but impairment was still observable compared to controls after 3 weeks of abstinence. Between group differences, however, need to be interpreted with caution as chronic smokers and controls were not matched for education, social economic status, life style and race.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Mean (SE) λc in the critical tracking task as a function of time of abstinence in chronic daily cannabis smokers. ‡ indicates significant difference (p<0.05) from baseline; * indicates significant difference (p<0.05) from control group.
N = 19 at baseline, N = 18 on day 8, N = 19 on days 14–16, N = 12 on days 21–23 and N = 30 for controls.
Figure 2
Figure 2. Mean (SE) number of control losses in the divided attention task as a function of time of abstinence in chronic daily cannabis smokers.
‡ indicates significant difference (p<0.05) from baseline; * indicates significant difference (p<0.05) from control group. N = 19 at baseline, N = 18 on day 8, N = 19 on days 14–16, N = 12 on days 21–23 and N = 30 for controls.
Figure 3
Figure 3. Mean (SE) tracking error on the divided attention task as a function of time of abstinence in chronic daily cannabis smokers.
‡ indicates significant difference (p<0.05) from baseline; * indicates significant difference (p<0.05) from control group. N = 19 at baseline, N = 18 on day 8, N = 19 on days 14–16, N = 12 on days 21–23 and N = 30 for controls.
See this image and copyright information in PMC

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