There are initial studies on the therapeutic effect of cannabinoid drugs in terms of a specific positive effect on ADHD symptoms.
In terms of cognitive performance and activity level, a slight but non-significant improvement was observed with Sativex. Hyperactivity/impulsivity (p=0.03) and cognitive inhibition (p=0.05) were significantly improved, inattention (p=0.10) and emotional lability (p=0.11) tended to be improved, although after statistical adjustment for multiple testing the significance was removed. One serious side effect (muscle seizures/convulsions) and three mild side effects occurred in the active group and one serious side effect (cardiovascular problems) in the placebo group.
The study concluded that cannabis medication may reduce ADHD symptoms for some adults with ADHD without cognitive impairment. One comprehensive meta-analysis found insufficient evidence of efficacy for ADHD, another found that studies support the efficacy and safety of cannabis for ADHD.
A UK study found symptom improvements from medicinal cannabis for ADHD over 12 months.
One study found a correlation between high doses of cannabinol (CBN) and reduced self-reported ADHD symptoms, as well as a correlation between high doses of medical cannabis and a reduction or complete substitution of other ADHD medications.
A comprehensive description of THC medications for ADHD can be found at ADHDpedia.
1. Cannabinoid receptors¶
There are two cannabinoid receptors.
1.1. CB1 receptor¶
The psychoactive effects of cannabis in the brain are mediated by the binding of its main component ∆9-tetrahydrocannabinol (THC) to CB1 receptors. Selective CB1 antagonists trigger a withdrawal syndrome in cannabinoid-dependent animals.
The CB1 receptor (cannabinoid 1 receptor) is present in many organs, sometimes in low concentrations.
It is one of the most common receptors in the brain. CB1 is found in:
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Cortex
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Hippocampus
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Amygdala
- the basal ganglia outflow tracts
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Cerebellum
The CB1 receptor is involved in the regulation of:
- Coordination of movements
- Spatial orientation
- Sensory perception (taste, smell, touch, hearing)
- Mental performance
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Motivation
- Pain
- Diclofenac inhibits pain via CB1 receptors, GPR55 receptors and mu-opioid receptors of mPFC and ventrolateral periaqueductal gray in the brainstem
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Inhibition of excessive signal transmission by neurotransmitters.
Activated CB1 receptors:
- inhibit GABA neurons, which leads to less inhibition of dopamine neurons. As a result, cannabinoids indirectly increase dopamine levels
- inhibit the overactivity of pain regulation and thus have a pain-relieving effect
- THC as a CB1 agonist has a dopamine-increasing effect in the nucleus accumbens. Adenosine A2A receptor antagonists (e.g. caffeine) counteract this.
Since the CB1 receptor is not present in the brainstem, which regulates respiration and the cardiovascular system, an overdose of THC is not thought to cause related deaths.
THC causes overstimulation of CB1 receptors, which impairs their ability to perform their physiological tasks, such as regulating food intake, metabolism, cognitive processes and pleasure. This leads to a reduction in memory and motivation and, in the long term, to addiction. Consequences are that heavy long-term cannabis use is associated with an increased risk of mental disorders, including psychosis, addiction, depression, suicidality and impaired cognition and motivation.
1.2. CB2 receptor¶
The CB2 receptor (cannabinoid 1 receptor) is primarily associated with the immune system.
2. Cannabis medication for ADHD¶
In Germany, Sativex, Cannabis Flos, Canemes and Dronabinol are several cannaboid drugs that are approved, but not for ADHD. For an off-label use for ADHD, an exemption had to be applied for from the BfArM in the past. Since 2017, a medical prescription of Sativex and Cannabis Flos for ADHD has been permitted under the BtmG without an additional exemption.
By 2017, around 150 people with ADHD had received an exemption (out of a total of 1061 granted). Cannabis prescriptions for ADHD have also risen sharply in other countries.
We are now aware of a double-digit number of reports from people with ADHD, as well as several people with ADHD personally, for whom medical cannabis has significantly reduced ADHD symptoms after MPH and amphetamine medication had not worked sufficiently.
In the case of an apparently massively THC-dependent person who is allowed to consume THC in a controlled manner, it is unclear whether this is based on the same effect or whether the effect is explained by the fact that the THC has merely eliminated the withdrawal symptoms of an existing THC addiction. This pattern is also known in alcohol addicts, who function “better” with their basic dose because the withdrawal symptoms are masked.
To summarize:
In Germany, cannabinoid medications may be prescribed for ADHD as a BtM prescription (like stimulants) if other medications are ineffective. Health insurance companies usually reimburse the costs on application.
3. Pathway from THC to dopamine¶
THC indirectly increases dopamine levels in the brain.
The THC cannabinoids do not act directly on dopamine neurons, but on the endocannabinoid system. Cannabinoid receptors are found in many areas of the brain that have dopamine neurons. Dopamine neurons themselves do not have cannabinoid receptors. However, dopamine neurons are inhibited by GABA neurons, which in turn have cannabinoid receptors.
THC activates CB1 receptors on GABA neurons, which inactivate the GABA neurons. This deactivates the GABA neurons that inhibit the dopamine neurons. The dopamine neurons are thus less inhibited and therefore more active.
THC as a CB1 agonist has a dopamine-increasing effect in the nucleus accumbens. Adenosine A2A receptor antagonists (e.g. caffeine) counteract this.
For the difference between medication and drugs, see ⇒ Medication and drugs - the difference.
4. Inhibition of sensory overload¶
Endocannabinoids (the body’s own cannabinoids) also act on the CB1 receptors and thus provide protection against sensory overload, among other things.
5. CBD-containing cannabis extract for ASD, anxiety and ADHD¶
One study treated a small group of people with ADHD with a CBD-enriched cannabis extract. The CBD to THC content was 75 to 1. Almost all people with ADHD showed improvements after 6 to 9 months, with ADHD symptoms often improving. The improvements were most pronounced in the non-epileptic persons with ADHD.
A review reports positive effects of cannabidiol in ADHD
A single dose showed no change in ADHD or attention symptoms in mice, but did show a reduction in anxiety symptoms.
Several people with ADHD told us that CBD oil (without THC) did not improve their ADHD symptoms.
However, a significant improvement was reported for anxiety disorders. Several people with ADHD reported that they were able to significantly reduce the previous dosage of their anxiety medication with CBD oil.
6. Cannabis treatment for tic disorders¶
A small study looked at the treatment of tic disorders with cannabis. An improvement in tics of 60% was found in 85% of people with ADHD, an improvement in comorbidities (most frequently OCB / OCD, ADHD and sleep disorders) in 55% and an improvement in quality of life in 93%. The effects were considered to be long-term. Half of the people with ADHD reported side effects, although their severity was judged to be tolerable. THC-rich strains seemed to work better.
Tic disorders share a genetic basis with ADHD.
7. Dosage and application instructions for medicinal cannabis¶
Information on dosing medicinal cannabis (Cannabis Flos) using a vaporizer can be found here.
