Research on over 6,000 adolescents reveals how the most popular illicit drug affects IQ.
The second most common medicinal use of cannabis is for mental health problems.
People with a family history of depression were more likely to experience cannabis withdrawal symptoms.
The short-term effects of smoking cannabis on cognition revealed by 69 studies on 2,100 cannabis smokers.
The short-term effects of smoking cannabis on cognition revealed by 69 studies on 2,100 cannabis smokers.
Heavy cannabis use does not have strong negative effects on memory or thinking skills, new research concludes.
The short-term intellectual effects of heavy pot use are minimal, the review of 69 studies including 2,100 pot users found.
Even the minimal effects quickly disappeared.
After abstaining from cannabis for 72 hours, young people’s cognitive skills were back to normal.
Dr J. Cobb Scott, who led the research, said:
“The length of abstinence was associated with how big the effect size was.
We don’t know if three days is a perfect cutoff for this.
We don’t know the maximum point at which abstinence might benefit cognitive functioning.”
The long-term effects of smoking cannabis are still unclear.
Teenagers could be at greater risk of psychosis or other problems as a result of long-term use.
Dr Scott said:
“The more you use cannabis, the more likely you are to have problems with cannabis, just like any other substance.”
People included in the 69 studies were between 18- and 30-years-old.
Smoking cannabis certainly had negative effects on cognition, but they were much smaller than expected.
Dr Scott said:
“It’s considered a small difference between groups, so the clinical significance of that is kind of questionable.
It does raise a question of how big are these differences in a practical sense, and what those differences mean in someone’s life.”
When young people stopped smoking cannabis their memory and thinking skills recovered from the slight deficit.
Dr Scott Krakower, a psychiatrist not involved with the study, said:
“They’re saying basically there’s not maybe as large of a difference in cognitive functioning, but they’re still saying there is potentially some cognitive dysfunction.
Even the smaller changes in cognitive function can still have long-lasting impacts on younger adults and adolescents.”
Dr Scott said:
“It’s important to think about the much longer-term effects of heavy use of cannabis, which this analysis doesn’t tell us that much about.”
The study was published in the journal JAMA Psychiatry (Scott et al., 2018).
One puff of this type of cannabis can help treat the symptoms of depression. Study also tests effect on anxiety and stress.
The neurochemical effects of coffee on the brain linked to cannabis by new study.
The neurochemical effects of coffee on the brain linked to cannabis by new study.
Coffee affects the same neurotransmitters as cannabis, new research finds.
Drinking four to eight cups of coffee a day decreased the levels of neurotransmitters in the endocannabinoid system.
In other words, coffee has the opposite effect to cannabis (sort of).
Coffee consumption may also help weight loss by having the opposite effect to cannabis: reducing the ‘munchies’, instead of spurring them on.
The endocannabinoid pathway is also important in how the body regulates stress.
The researchers were surprised by the wide-ranging effects of coffee consumption on the human metabolism.
It apparently does way more than just waking us up in the morning.
Dr Marilyn Cornelis, the lead author, said:
“These are entirely new pathways by which coffee might affect health.
Now we want to delve deeper and study how these changes affect the body.”
People in the study abstained for coffee for one month and then consumed four cups in the second month and eight cups in the third month.
Blood tests revealed that coffee consumption reduced activity in the endocannabinoid system, particularly on eight cups per day.
Dr Cornelis said:
“The increased coffee consumption over the two-month span of the trial may have created enough stress to trigger a decrease in metabolites in this system.
It could be our bodies’ adaptation to try to get stress levels back to equilibrium.”
The endocannabinoid system is also involved in many other bodily process, such as cognition, blood pressure, immunity, addiction and sleep.
Dr Cornelis said:
“The endocannabinoid pathways might impact eating behaviors, the classic case being the link between cannabis use and the munchies.”
Coffee is sometimes linked to weight loss, Dr Cornelis said:
“This is often thought to be due to caffeine’s ability to boost fat metabolism or the glucose-regulating effects of polyphenols (plant-derived chemicals).
Our new findings linking coffee to endocannabinoids offer alternative explanations worthy of further study.”
The study was published in the Journal of Internal Medicine (Cornelis et al., 2018).
Studies tested how cannabis use affects creativity, error detection and neurotransmitters.
Studies tested how regular cannabis use affects creativity, error detection and neurotransmitters.
Regular cannabis use is linked to worse creative thinking, new research concludes.
They also find it harder to spot their own mistakes.
The conclusions come from a series of studies carried out by psychologist Mikael Kowal.
One of the studies tested people’s brainstorming abilities.
It showed that regular cannabis users performed worse.
Mr Kowal said:
“There is a widespread belief among users that these drugs enhance creativity.
This experiment disproves that belief.”
Another study tested how good people were at detecting their own mistakes.
Again, regular cannabis users performed poorly.
Mr Kowal said:
“It is important that we gather more knowledge about the effects of cannabis on a person’s ability to detect mistakes.
This can help with putting together a treatment programme for drug addiction.”
In the long-term cannabis disrupts the activity of the neurotransmitter dopamine.
One sign of this is that regular users blink significantly less than non-users.
Mr Kowal concluded:
“More research is needed on the effects of cannabis and on the individual consequences it can have on mental functions.”
The studies are part of Mr Kowal’s PhD.
Occasional cannabis users were tested along with those addicted to the drug.
Occasional cannabis users were tested along with those addicted to the drug.
A single ‘spliff’ is enough to reduce the motivation to work, new research finds.
It is the first study to show the problematic short-term effects of cannabis on motivation.
Dr Will Lawn, the study’s first author, 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.
It has also been proposed that long-term cannabis users might also have problems with motivation even when they are not high.
However, we compared people dependent on cannabis to similar controls, when neither group was intoxicated, and did not find a difference in motivation.
This tentatively suggests that long-term cannabis use may not result in residual motivation problems when people stop using it.
However, longitudinal research is needed to provide more conclusive evidence.”
The study involved people who used cannabis occasionally.
They were offered small amounts of money for performing a series of tasks involving pressing the space key on a computer keyboard.
Sometimes they had inhaled cannabis smoke beforehand, other times they inhaled a placebo that did not contain cannabis.
Professor Val Curran, a senior study author, said:
“Repeatedly pressing keys with a single finger isn’t difficult but it takes a reasonable amount of effort, making it a useful test of motivation.
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% of the time for a £2 reward, whereas volunteers on cannabis only chose the high-effort option 42% of the time.”
A second study carried out a similar test on people who were addicted to cannabis rather than just being occasional users.
The addicts showed similar motivation levels to the control group.
So this study provided no evidence that cannabis affects motivation in the long-term.
The study was published in the journal Psychopharmacology (Lawn et al., 2016).
→ The effects of regular cannabis use on creativity.
The neuroprotective effect of this common drug on Alzheimer’s.
The neuroprotective effect of this common drug on Alzheimer’s.
Compounds in marijuana could help to prevent Alzheimer’s disease, new research finds.
The compounds, which include tetrahydrocannabinol, can promote the removal of a toxic protein related to Alzheimer’s disease.
It could help to explain why exercise — which produces natural endocannabinoids — is also protective against Alzheimer’s.
Professor David Schubert, senior author of the study, said:
“Although other studies have offered evidence that cannabinoids might be neuroprotective against the symptoms of Alzheimer’s, we believe our study is the first to demonstrate that cannabinoids affect both inflammation and amyloid beta accumulation in nerve cells.”
The tests were carried out on neurons grown in the laboratory.
Researchers found that exposing these cells to THC — the active component of marijuana — reduced the levels of the toxic protein linked to Alzheimer’s.
It also eliminated the inflammatory response.
Dr Antonio Currais, the study’s first author, explained:
“Inflammation within the brain is a major component of the damage associated with Alzheimer’s disease, but it has always been assumed that this response was coming from immune-like cells in the brain, not the nerve cells themselves.
When we were able to identify the molecular basis of the inflammatory response to amyloid beta, it became clear that THC-like compounds that the nerve cells make themselves may be involved in protecting the cells from dying.”
It is now yet known if THC could provide a useful therapy against Alzheimer’s.
This would need to be tested in clinical trials.
However, one small trial has already found that medical cannabis oil containing THC can help people with the symptoms of dementia (Shelef et al., 2016).
This trial found a significant reduction in psychological and behavioural symptoms of dementia such as agitation, aggression, delusions and apathy.
The study was published in the journal Aging and Mechanisms of Disease (Currais et al., 2016).
Alzheimer’s image from Shutterstock
Alcohol plus cannabis is one of the most frequently detected combinations of drugs in car accidents.
Alcohol plus cannabis is one of the most frequently detected combinations of drugs in car accidents.
Alcohol and cannabis taken together may increase the effect of the cannabis, a new study finds.
This may be why, in car accidents, alcohol plus cannabis is one of the most frequently detected combinations of drugs.
Taking both drugs together significantly increases the levels of cannabis’ main psychoactive ingredient, THC (tetrahydrocannabinol) in comparison to taking cannabis alone.
For the research, 19 adults either took doses of cannabis or a placebo.
Both were combined with alcohol.
Tests demonstrated significantly higher levels of THC when the same amount of cannabis was taken with alcohol rather than with a placebo.
Dr Marilyn A. Huestis, the study’s first author, said:
“The significantly higher blood THC and 11-OH-THC [median maximum concentration] values with alcohol possibly explain increased performance impairment observed from cannabis-alcohol combinations.
Our results will help facilitate forensic interpretation and inform the debate on drugged driving legislation.”
The study was published in the journal Clinical Chemistry (Huestis et al., 2015).
→ The effects of regular cannabis use on creativity.
Cannabis user image from Shutterstock
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