ADHD or substance effects? Cannabis, alcohol, stimulants and focus

An adult who smokes cannabis most evenings, drinks heavily on weekends, or uses someone else's stimulant pills to get through deadlines may notice poor focus, forgetfulness, restlessness and bad sleep. Those are also signs of ADHD. Sometimes the substance is causing the problem. Sometimes ADHD came first and the substance is a way of coping. Often it is some of both. This page explains how clinicians approach the question, without judgment.

How each substance can mimic ADHD

Cannabis

The National Institute on Drug Abuse (NIDA) says cannabis intoxication can cause altered time perception and impaired thinking, memory and body movement, and can make some people irritable or restless. Frequent or heavy use has been linked to problems with learning and memory, attention, processing speed, perceptual motor function and language. After stopping heavy or long-term use, some people have withdrawal, which NIDA says can include irritability, anxiety, restlessness, low appetite, depression, insomnia and strange dreams. One study cited by NIDA estimated that 12.1% of people who use cannabis frequently experience withdrawal.

Restlessness, irritability and poor sleep during withdrawal can easily be read as ADHD. So can memory and attention problems during regular heavy use.

Alcohol

The National Institute on Alcohol Abuse and Alcoholism (NIAAA) says alcohol interferes with the brain's communication pathways and makes it harder for brain areas controlling balance, memory, speech and judgment to do their jobs. It can cause blackouts, gaps in memory for events that happened while intoxicated. During a hangover, NIAAA says, attention, decision-making and muscle coordination can be impaired, and symptoms can last 24 hours or longer. Someone who drinks heavily several nights a week may spend much of the week either intoxicated or recovering.

NIAAA also notes that at least some brain changes linked to alcohol use disorder, and the changes in thinking that come with them, can improve and possibly reverse with months of abstinence.

Stimulants not prescribed to you

NIDA says methamphetamine's short-term effects include euphoria and increased alertness and energy, and that long-term use may lead to insomnia, memory loss and a substance use disorder. For cocaine, NIDA describes how regular use makes the brain's stress circuits more sensitive, leading to displeasure and negative moods when not using, which are signs of withdrawal.

Some adults use prescription stimulants without a prescription to study or work. A study of 898 college students without an ADHD diagnosis found that those who used prescription stimulants nonmedically showed no increase in their grades and gained no detectable advantage over peers. The authors called the promise of academic benefit likely illusory. Feeling sharper on someone else's medication is not evidence of ADHD, and it is not a safe way to find out.

The key differences

Sources for the table: NIMH's adult ADHD publication for the ADHD column; NIDA's cannabis, methamphetamine and cocaine pages and NIAAA's alcohol and brain and hangover pages for the substance column.

Why ADHD and substance use so often go together

The overlap is large. A 2012 meta-analysis in Drug and Alcohol Dependence pooled 29 studies and found that 23.1% of people with substance use disorders met diagnostic criteria for ADHD, almost one in four. NIMH notes that teens and adults with ADHD are more likely to engage in risky behaviors such as substance use. NIDA explains that people may use drugs to try to feel better when they have untreated mental health symptoms, and that although some substances may temporarily reduce symptoms, they can also make symptoms worse, both right away and over time. NIDA also notes that people with both ADHD and a substance use disorder often report stronger cravings.

That is why an adult who uses substances heavily is not automatically ruled out for ADHD, and why an ADHD diagnosis does not explain away a substance problem. Each needs its own look. The NY guide's ADHD and substance use article covers treatment questions, and the NJ guide explains ADHD medication and cannabis in New Jersey.

How clinicians sort it out

NICE guidance on ADHD says assessment should include coexisting conditions, especially drug misuse, and that adults should be assessed when ADHD symptoms began in childhood, persisted throughout life and are not explained by other psychiatric diagnoses. Before starting medication, NICE calls for a risk assessment for substance misuse and drug diversion. In practice, an evaluator will want to know:

• Whether attention and restlessness problems were present in childhood, before any substance use
• What you use, how much and how often, and when you last used
• Whether symptoms change during periods when you use less or not at all
• Whether you have used stimulants that were not prescribed to you, and how they affected you
• Family history of ADHD and of substance use problems

Childhood history matters most, because it comes from a time before use began. Reports from parents or siblings help; see how to ask family about childhood symptoms. Being honest about use protects you: it lets the evaluator interpret your symptoms correctly and choose treatment safely. Dr. Shershow's evaluation covers substances along with current symptoms, childhood and work history, medical history, sleep and other explanations, and ends with what it found and the treatment options that fit. How to prepare for an evaluation lists what to bring.

When to talk to a clinician

Consider an evaluation if attention problems go back to childhood and persist even during periods of little or no use, or if you find yourself relying on a substance to focus, calm down or sleep. If your use feels out of control, that deserves care in its own right. The adult ADHD self-test can help you organize what you notice, though it cannot separate ADHD from substance effects. Adults in New York or New Jersey can read ADHD testing in NYC or ADHD testing in New Jersey to see how an evaluation with Dr. Shershow works. In a crisis, call or text 988 at any hour, or 911 in an emergency.