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  • Writer's picturePetra

Cannabis and ADHD: Weighing the Pros and Cons

In my work with adults diagnosed with ADHD, I have encountered numerous individuals who frequently use cannabis, often on a daily basis. A common pattern is to use cannabis before bedtime to aid in falling asleep. This is not unexpected, considering the prevalence of sleep issues, particularly difficulties in falling asleep, in individuals with ADHD. Clients also report that cannabis helps slow down their thoughts and calm their minds, and some even experience improved focus and attentional capacity. However, these effects are not universal. Many adults with ADHD have shared negative experiences, such as feeling physically unwell or vomiting, increased anxiety, or experiencing an unpleasant loss of control.

Firstly, let's discuss the potential benefits of cannabis for adults with ADHD. Some research suggests that cannabis may help alleviate certain ADHD symptoms, such as hyperactivity and impulsivity. In some instances, it has even been reported to enhance focus and concentration, which are typically challenging for those with ADHD. There are medical cannabis prescribers in New Zealand who believe that cannabis use can be beneficial for ADHD symptoms, so it is not hard to get a medical prescription.

One plausible explanation for these benefits, as well as the calming effects and sleep assistance, is that cannabis increases dopamine levels in the brain. Dopamine is a neurotransmitter that plays a significant role in attention, motivation, and the brain's reward system. Given that stimulant medications dramatically increase the availability of dopamine in the brain, it is perhaps unsurprising that cannabis may help alleviate ADHD symptoms in a similar way in some individuals.

Now, let's explore the flip side: the potential drawbacks of regular cannabis use. One major concern is that habitual use can lead to dependence. This can be particularly problematic for individuals with ADHD, who as a group are already more susceptible to substance use disorders. Furthermore, long-term cannabis use has been linked to cognitive impairments, such as memory issues and reduced attention span. These effects can be especially detrimental for adults with ADHD, who often struggle with these cognitive functions to begin with. Moreover, cannabis use may exacerbate anxiety and mood disorders, which are common comorbidities with ADHD. One study found that cannabis users had a lower dopamine response to stimulant medication (methylphenidate), suggesting that concurrent cannabis use might diminish the effectiveness of stimulant medication. This study also found that frequent cannabis users had lower scores on positive emotionality and higher scores on negative emotionality. Additionally, there are physical health issues associated with smoking (and possibly vaping) cannabis, such as chronic obstructive pulmonary disorder or exacerbating asthma.

It is worth noting that cannabis use without a medical prescription is illegal in New Zealand, and even when sanctioned, there are restrictions on its use. For instance, driving under the influence of cannabis is prohibited, and it could affect a person's employment if their job has a drug-free policy.

General practitioners often require urine testing for illicit substances when a person is prescribed stimulant medication. In Canterbury, for example, there is a specific threshold for THC in a person's urine that, if exceeded, will preclude them from being prescribed cannabis. This includes medically prescribed cannabis (CBD oil should not be an issue, as it contains negligible levels of THC). Since THC accumulates in fat stores, it can take several weeks to detox to acceptable levels for receiving stimulants, and increased use could jeopardise ongoing prescriptions.

On balance, I tend to believe that cannabis typically acts as self-medication for ADHD symptoms that could be more effectively treated with prescribed stimulant medication. I have encountered few people who regularly use cannabis and are completely satisfied with their usage level, without any desire to reduce it. A handful of clients have admitted to being dependent on it. I have also had clients whose cannabis use has decreased naturally after they started stimulant medication.

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