Heart attack risk to casual cannabis users
CANNABIS users are three times as likely to die from high blood pressure, even if they do not smoke it frequently.
The danger rises for every year someone uses the drug, a study found.
Marijuana’s effects on the cardiovascular system are already known from people taken to hospital with heart attacks and angina after use. But the new findings raise fears over high blood pressure, which puts extra strain on the blood vessels, heart and other organs such as the brain.
Left untreated, it can kill people by causing strokes or kidney disease, as pressure on the small blood vessels stops the organs working properly.
Evidence has previously been found to link marijuana with psychosis and schizophrenia, aggression and memory loss.
The latest study of 1,213 people by Georgia State University in the US found those who had used marijuana were 3.42 times as likely to die from high blood pressure. Lead author Barbara Yankey said: ‘This is not surprising since marijuana is known to have a number of effects on the cardiovascular system.
‘Marijuana stimulates the sympathetic nervous system, leading to increases in heart rate, blood pressure and oxygen demand. Emergency rooms have reported cases of angina and heart attacks after marijuana use.’
Smoking marijuana can double someone’s heart rate for up to three hours afterwards. The main psychoactive, mind-altering ingredient in the drug, tetrahydrocannabinol (THC), has been found to lead to strokes, dizziness and fainting.
That is because cannabinoid receptors, which deliver the high when someone smokes the drug, are also part of the cardiovascular system.
To investigate how this affects blood pressure, the researchers carried out a followup study of adults aged 20 and over involved in a national health survey. The average length of use for those considered marijuana users was 11.5 years. This group’s triple risk of dying from high blood pressure included deaths from kidney disease.
Responding to the findings, Dr Amitava Banerjee, honorary consultant cardiologist at University College London, said: ‘This study adds to evidence for long-term cardiovascular risks of marijuana use.
‘A systematic review last month showed that 29 previous observational studies have looked at this question, and suggested that the link between marijuana and strokes was stronger than for any other cardiovascular diseases.’ However the study published in the European Journal of Preventive Cardiology is small, British experts said, and it assumed people had continued smoking when they may not have done.
Dr Tim Chico, a consultant cardiologist from the University of Sheffield, said: ‘Although this paper has limitations, there is enough evidence from other research to strongly suspect marijuana use increases the risk of some forms of heart disease, and it is certainly not harmless.’
It also warned that marijuana users in Britain smoke the drug with tobacco, which ramps up the risk of circulation and heart problems still further.
While the US study found no link between cannabis and death from heart disease or cerebrovascular diseases such as stroke, Miss Yankey warned support for liberalisation of laws guarding its use needed to be balanced against the ‘health, social and economic risks’.