Research has revealed that consuming even a tiny amount of cannabis affects a person’s motivation to work.

Those who have taken cannabis are more likely to avoid tasks which require effort, even if they have just smoked a single joint. And there are concerns that this could have serious implications for the career prospects of long-term users of the class-B drug.

The study was carried out by University College London and involved 57 volunteers. One group, which was made up of 17 people who used cannabis occasionally, were asked to inhale the same amount of the drug which is found in a typical joint before picking between two tasks to complete.

They could opt to do an extremely easy task – pressing the spacebar on a computer keyboard 30 times in seven seconds – to earn 50p. Or they could choose to work harder for more money and press the spacebar 100 times in 21 seconds to earn up to £2.

The group were then given the choice of tasks again when they had not consumed any cannabis but had instead inhaled a placebo vapour.

Drug users avoided tasks involving effort

Professor Val Curran, who was involved in the research which was published in the Psychopharmacology Journal, said: “We found that people on cannabis were significantly less likely to choose the high-effort option. On average, volunteers on placebo chose the high-effort option 50 per cent of the time for a £2 reward, whereas volunteers on cannabis only chose the high-effort option 42 per cent of the time.”

The second group of volunteers was made up of 20 cannabis addicts who were matched with individuals who had never taken the drug. They were banned from having any drugs or alcohol for 12 hours before they took part in the study.

They were given the same choice of tasks as the first group and the results showed no difference in motivation between the regular drug users and those who steer clear from illegal substances.

Dr Will Lawn, who led the study, said: “Although cannabis is commonly thought to reduce motivation, this is the first time it has been reliably tested and quantified using an appropriate sample size and methodology.”

Cannabis affecting an individual’s motivation and productivity is just one of the reasons an employer might want to monitor substance misuse in the workplace. Another major concern is that staff taking drugs like cannabis could cause health and safety issues for themselves, other employees and members of the public.

AlphaBiolabs carries out workplace drug testing to detect a range of illegal substances, including cannabis. We work with employers to carry out a programme which suits their needs, which could include a regime of random testing, pre-employment screening, for-cause and post-incident testing and abstinence monitoring.