Here’s the Truth About Cannabis for ADHD
Early studies show that cannabinoids are at least as effective as currently accepted pharmaceuticals for the treatment for ADHD, without the side effects.
Attention deficit/hyperactivity disorder (ADHD) is currently estimated to affect 5% of children and 3% of the adult population. The affected individuals display inappropriately high levels of inattention, hyperactivity and impulsivity that are commonly accompanied by emotional lability and psychiatric disturbances. Pharmacological treatment of ADHD is currently accomplished with amphetamines, specifically drugs such as Attentin® and Adderall®.
In ADHD, transmission of neurotransmitters such as dopamine and norepinephrine, are disturbed and the mechanism of action of these drugs is by either inhibiting reuptake of the neurotransmitters or directly affecting their release. Higher doses of the drug can cause euphoria and as such, are potentially dangerous substrates for misuse and addiction.
Another FDA approved drug for ADHD treatment is in the class of methamphetamines. Yes, the same methamphetamine that is a highly addictive, psychoactive drug of abuse that affects the central nervous system. It is prescribed by the commercial name Desoxyn with an effective dose of 20-25mg daily. Methamphetamine is an example of a chemical compound that, depending on the dose, can act as a beneficial pharmacotherapy and then also be a potent, highly addictive drug of abuse. At low doses, methamphetamine enhances dopaminergic transmission and attenuates hyperactivity, inattention and behavioural variability. However, it is usually prescribed only for short periods of time due to its addictive properties.
It is common in clinical practice for adults with ADHD to report cannabis use. The beneficial aspects of cannabis they report include feeling calmer, improved sleep, decreased restlessness. Despite the abovementioned pharmacological treatments that exist for ADHD, patients often do not find relief, the drugs are not well tolerated or have only partial effect. In more extreme cases, adverse effects have been observed, such as cardiovascular effects, growth suppression and the development of psychoses. Therefore, development of novel treatments can fulfill this insufficiency in effectiveness and also could reveal novel mechanisms underlining the disorder.
Investigations into the potential of cannabinoids as therapeutics for ADHD have not been extensively carried out until recently. In 2017, a pilot study was completed investigating the beneficial effects of Sativex, an oromucosal spray consisting of THC and CBD in 1:1 ratio in adults with ADHD. This pilot study was a 6-week single center, double-blind, placebo-controlled study conducted in United Kingdom. They found that in the group receiving Sativex, significant improvements were observed in hyperactivity and impulsivity, with trends towards improvement for inattention and emotional lability, while no negative effects on these primary outcomes were observed.
One potential mechanism by which cannabinoids would be therapeutically beneficial in ADHD patients may be the anxiolytic effects (anti-anxiety) of CBD and THC that has been observed to occur in healthy subjects after acute administration. The resultant calming effect may have led to observed reductions in feeling restlessness and impulsive behavior in the participants of this study. Other proposed mechanisms for therapeutic benefits of cannabinoids in ADHD have been speculated to involve enhancement of dopaminergic transmission. Particularly, alterations in dopamine in a specific brain region called the striatum may be affected, as it has been shown that the striatal dopamine modulates the endocannabinoid system. Other studies have found that THC administration increases dopamine in this and other brain regions though to be involved in ADHD.
In other words, cannabinoids seem to potentiate dopaminergic signaling in the relevant brain regions for ADHD, similar to the stimulant drugs that are commonly prescribed but without the side effects and lack of tolerance by the ADHD patients. In fact, in the study described above, the only negative feedback regarding Sativex was sleepiness (occurred in 3 cases) and slower thoughts (also occurred in 3 cases). Collectively, CBD and THC with their anxiolytic effect and potential impact on dopaminergic signaling may be a superior alternative to the existent pharmacological treatments for ADHD. Since the pilot study conducted in the UK enrolled only 30 patients, larger scale studies are needed to further the knowledge of the effects of cannabinoids in ADHD pharmacotherapeutics.