text: University students who smoke cannabis can expect to get lower grades across the board but especially if they are studying maths, a new study has revealed. Statistics collected at Maastricht University in Holland, where cannabis is decriminalised, have shown that students who were able to buy the drug from coffee shops were five percent less likely to pass their courses. At the same time, foreign students who did not have ready access to the mind bending drug did better on average, the Observer reported. The study will rankle with the increasing number calling for the legislation of cannabis around the world . Economists Olivier Marie from the Dutch University and Ulf Zölitz of IZA made their findings based on what happened in Maastricht in 2011 when the city let only German, Dutch and Belgian nationals have access to its 13 coffee shops, where cannabis was sold. The restriction was put in place to combat drug tourism which was thought to be tarnishing the city’s image. Tourists particularly from France and Luxembourg were visiting Masstricht solely to smoke cannabis. Marie and Zölitz studied the 54,000 sets of grades from students all around the world and came to a stark conclusion. In a paper recently unveiled at the Royal Economic Society conference in Manchester the economists showed plainly that those without easy access to the drug did better in their studies on average. The temporary prohibition constrained consumption amongst the non-German, Dutch and Belgian nationals and their brain function improved. Students who were able to buy the drug from coffee shops were five percent less likely to pass their courses . Marie was quoted as saying the difference was found to be similar to those observed in the US when students reach legal drinking age. The change before and after restriction was seen to be even more pronounced amongst ‘low achievers’. Without access to cannabis they had a 7.6 percent chance of passing the courses. The pair also came to stark conclusions when looking at stats for maths students. For those courses numerical skills the policy effect was ‘five times larger’. For those stuying courses with numerical skills the policy effect was ‘five times larger’, the Maastricht University (pictured) study stark concluded . While there is increasing clamour for the legalisation of cannabis across the world, the economists say there is very little evidence of how the drug – which has been linked to psychosis – affects society. Coffee shops may start to spring up in Berlin with Uruguay planning to be the first country to fully legalise the drug. The drug study says: ‘If marijuana is legalised like it is in many states in the US, we should at least inform consumers about the negative consequences of their drug choices.’ Consuming THC – tetrahydrocannabinol – the active ingredient in Cannabis is much the same as drinking pure vodka it concludes. Marie, a father, said the study has informed how he advises his own 13-year-old son, about cannabis and he shares the findings as a precautionary measure. The economists say there is little evidence of how the drug, linked to psychosis, affects wider society .
target: Study at Maastricht University found access to drug lowered grade scores .
  Those who could buy cannabis legally did 5% worse across all courses .
  Statistics were worst for maths students or those developing number skills .
  Economists say more to be done to investigate the drug's affect on society .