ADHD in adults with anxiety, depression or another condition: what we know about medication

When someone starts ADHD medication, it is reasonable to ask how we know it works. The short answer is that it has been tested in many clinical trials. The question almost nobody asks is a different one: are the people who take part in those trials like you? If, besides ADHD, you have anxiety, take antidepressants or have had problems with alcohol or other substances, the answer is worth knowing.

A Swedish study published in 2025 in the journal The Lancet Psychiatry (Garcia-Argibay and colleagues) estimated it using the country’s national health registries. Here is what it found, what it cannot say and what it means in practice.

How is ADHD medication tested?

The main evidence on how well ADHD medication works comes from clinical trials, which are considered the standard for evaluating a treatment: studies in which one group receives the medicine and another a placebo, and the change in symptoms is compared. According to the international consensus of the World Federation of ADHD (2021), those trials usually follow patients for a few weeks. I explained what they show about efficacy in Does ADHD have a cure? What works in treatment.

For a trial to measure the effect of a medicine clearly, its participants are chosen with strict criteria. People who have other conditions, take other medicines or have certain health risks are usually left out. That makes the results cleaner. It also makes them look less like what is seen in the clinic.

What did the Swedish study do?

In Sweden, diagnoses and the prescriptions dispensed by every pharmacy are recorded in national databases: the health registries. With them, the study by Garcia-Argibay and colleagues did three things:

1. It identified everyone diagnosed with ADHD between 2007 and 2019 who was at least 4 years old at diagnosis, and kept only those who collected at least one prescription for ADHD medication from a pharmacy: 189,699 people, from children to adults.
2. It gathered the exclusion criteria of 164 clinical trials of ADHD medication, that is, the reasons they left someone out, and used only those that appeared in at least 30% of those trials, that is, the most common ones.
3. It looked for those reasons in the year before each person started medication.

An important detail: nobody was assessed for a real trial. The authors simulated who could have been enrolled, using the diagnoses and prescriptions recorded in the registries. That is why, in this article, I talk about people who “would have been left out”.

How many adults would have been left out of the trials?

According to that simulation, about 3 in 4 adults (74%) who started ADHD medication in Sweden would have been left out of typical trials.

In the same study, the proportion was much lower in children and adolescents: 21% of children and 35% of adolescents would have been left out. In this study, the mismatch between the trials and real life was much greater in adults.

Why would they be left out?

In the trials analyzed, the most common reason for leaving someone out was taking antidepressants: it appeared in 121 of the 164 trials. Other frequent reasons were psychosis, bipolar disorder, problematic substance use, cardiovascular disease, anxiety and autism.

Looking at the people, the profile becomes more concrete. Among the adults who would have been left out:

• 79% had used antidepressants in the year before starting ADHD medication (this is the record of the prescription, not necessarily a diagnosis of depression);
• half (52%) had an anxiety diagnosis recorded in that year;
• and 34% had a substance use disorder recorded.

None of this is unusual in adult ADHD. The European consensus on adult ADHD (2019) estimates that 60–80% of adults with ADHD will have another psychiatric disorder at some point in their lives, and the international consensus summarizes that ADHD often occurs together with depression, bipolar disorder, autism, anxiety or substance use. What the trials treat as an exception is the norm in the clinic.

Do people who would have been left out do worse on medication?

This is the question that matters most, and the study answers it only in part.

The authors expected that those who would have been left out would stop their medication more often. That did not happen in adults. In the first year, they switched medication somewhat more often than the rest (30% versus 25%), but they stopped it somewhat less often: 26% stopped it, versus 32% of those who would have been eligible. The authors note that switching medication does not necessarily mean the first one failed: it can also be a planned strategy in complex cases. And they suggest that more switching with less stopping could indicate that adjusting the treatment helps to find a medicine that works.

There were also more psychiatric hospitalizations in the year after starting medication: in adults, 13% had at least one, versus 3% of those who would have been eligible. The authors themselves say this was expected, because the same conditions that leave someone out of a trial predict a more difficult course. When they took into account how ill people were in the previous year, the difference in the number of hospitalizations shrank a lot, but it did not disappear: hospitalizations were still more than twice as frequent. The authors explain this, at least in part, by the difficulties those people already had beforehand, and they do not attribute it to the medication. Since everyone had started medication, the study cannot fully separate one thing from the other. Nor is it a prognosis for any particular person: it describes a group that was already starting out with more difficulties.

What the study cannot say is whether the medication helped them more or less than the others. Everyone in the study had started medication, so there was no group without treatment to compare with. And the registries have no symptom or quality-of-life scales, so it did not measure whether ADHD symptoms improved either. Stopping medication less often is not the same as getting better.

Does this mean the trials are useless?

No. The authors do not say trials are unnecessary: they consider them key to establishing what a treatment can achieve. Their conclusion is that evidence from other types of study, such as pragmatic trials and real-world studies, needs to be added in order to decide on treatment. They describe it as a paradox: the people who would most need evidence-based guidance are the least represented in the trials.

The authors also warn that, because people who enter trials have less complicated conditions, the results might not accurately estimate efficacy or side effects when applied to everyone, and that in those who are left out, especially if they have several physical illnesses, drug interactions and side effects might be more likely. This is a warning, not something the study measured.

The British NICE guideline independently reaches a similar conclusion: it recognizes that there is very little evidence on which medication to choose when ADHD comes with other conditions, and it notes that people with ADHD and tics, a history of psychosis or mania, or emotional dysregulation are usually left out of trials.

And the Swedish study has its own limits, which go in both directions:

• It applied common criteria, but not universal ones. Some trials are more inclusive, so the true proportion excluded could be lower.
• It could not apply other trial requirements, such as a minimum level of symptoms, because the registries do not have that information. That could make the true proportion higher.
• It is Sweden: a public, universal health system, with one of the highest rates of ADHD prescriptions in the world. The results might not apply in the same way in other countries. I am not aware of an equivalent study done in Peru.

If I have ADHD and another condition, what does it mean for me?

First, that having another condition does not usually close off the options. For anxiety, autism or tics, NICE recommends offering the same medication options as to anyone else with ADHD, and does not consider it justified to choose a different one because of those conditions. When there is another mental health condition (for example, depression), or a neurodevelopmental or physical condition, what it asks for is more care in the process: increasing the dose more slowly and having more frequent check-ups. Some situations change the plan. During an episode of psychosis or mania, NICE recommends stopping ADHD medication and considering restarting it once the episode has resolved. In bipolar disorder, the European consensus says to use stimulants only together with a mood stabilizer. And if there is a risk of misuse, NICE rules out certain formulations of stimulants. Those decisions are made with your doctor.

Second, that treatment is planned as a whole. According to the European consensus, adult ADHD is treated most of the time together with other disorders, and it recommends identifying all of them before starting, in order to decide together with the person in what order to treat them. In general, the most serious comes first: psychosis, bipolar disorder, substance use or severe depression or anxiety are usually treated first, while milder mood or anxiety conditions can be treated at the same time as ADHD. Since combining medicines is common, the consensus asks for possible interactions to be taken into account.

With substance use, the European consensus notes that treating ADHD can reduce ADHD symptoms without worsening substance use, and that ADHD treatment should not be withheld. That does not mean the medication treats the substance use: according to the trials collected by the same consensus, its effect on the substance use itself was limited, and substance use must be stabilized, although it can be treated at the same time as ADHD. Before starting, the NICE guideline asks for the risk of misuse of the medication to be assessed.

Third, that follow-up matters more. NICE warns that how much stimulants help, how long their effect lasts and their side effects vary from one person to another. It also recommends encouraging people who take ADHD medication to monitor and record their side effects, for example with a checklist, and reviewing the medication at least once a year. With stimulants, the European consensus recommends measuring pulse, blood pressure, sleep and weight before starting, and monitoring them at least twice a year; the same consensus clarifies that serious heart complications are rare. The international consensus states that, in general, side effects are mild and can be managed by adjusting the dose or changing medication. With other conditions or several medicines, it is follow-up that confirms this for each person.

In practice, in my consultations I ask three things of anyone starting treatment:

• To tell me everything they take and anything that may matter: medicines, including antidepressants, anti-anxiety medicines, those bought without a prescription and supplements; whether they use alcohol or other substances, even occasionally; whether they are pregnant, breastfeeding or trying to get pregnant; and whether they have heart problems, high blood pressure, fainting on exertion or a close relative who died suddenly before the age of 40.
• To write down how they feel in the first weeks: sleep, appetite, mood, anxiety, palpitations. That information, added to what the trials show, is what makes it possible to adjust the treatment to each person.
• Not to stop any medicine or change its dose on their own, whether it is the ADHD medication or any other: any change is discussed with their doctor.

When not to wait for the next check-up. If you have chest pain, faint or get short of breath with little effort, go to the emergency room or call 106 (SAMU, Peru’s emergency medical service). Message or call your doctor the same day if you notice strong palpitations or palpitations that don’t go away; if you are sleeping very little without feeling tired, or feel much more sped up and energized than is usual for you, making plans or spending money in ways that aren’t like you; if you perceive things that others don’t perceive or distrust everyone for no reason; or if your mood or anxiety gets much worse. If you have thoughts of death or of harming yourself, seek help immediately: go to the nearest emergency room or, in Peru, call 106 (SAMU) or call 113 and choose option 5 (mental health; the line operates in Spanish).

And medication is not the only tool: I wrote about the others in Does ADHD have a cure? What works in treatment.

Frequently asked questions

Can I take ADHD medication if I already take antidepressants?
Often yes, but not with just any combination. Taking antidepressants was the most common reason for being left out of the trials, so there is less direct evidence for this situation. The European consensus asks for interactions to be taken into account: some combinations are generally contraindicated and others can raise blood pressure or pulse, and so need more monitoring. Your doctor needs to know exactly which antidepressant you take. Do not stop or change it on your own in order to start ADHD medication.

If I have anxiety, will ADHD medication work worse for me?
A 2025 Swedish study cannot answer this, because all the participants were taking medication and it did not measure symptoms. The British NICE guideline recommends offering people with anxiety the same options as anyone else with ADHD, with more frequent check-ups. With stimulants, some people who already have anxiety may find that their anxiety gets worse: if that happens to you, do not stop the medication on your own; tell your doctor.

Does this mean the evidence for ADHD medication is worthless?
No. Trials show what a medicine can achieve under controlled conditions, and that evidence is still the foundation. What a 2025 Swedish study points out is that, for many adults with other conditions, the evidence is less direct, and that is why individual follow-up matters more.

Do the Swedish study's data apply to Peru?
Not directly. They come from Sweden, a country with a public health system and one of the highest rates of ADHD prescriptions in the world, so the exact figure cannot be transferred. What the international consensus statements do describe is that adult ADHD usually comes with other conditions.

This article is for information purposes only and does not replace an individual medical evaluation or create a doctor-patient relationship. Do not start, change or stop any treatment without discussing it with your doctor.

Prevention message

“Un suicidio puede evitarse si lo hablamos a tiempo. Si necesitas consejo, orientación o ayuda, llama gratis al 113, opción 5. Aquí estamos para ayudarte.”

(Unofficial translation: “Suicide can be prevented if we talk about it in time. If you need advice, guidance or help, call 113, option 5, free of charge. We are here to help you.”)

Línea 113, opción 5 · Ministerio de Salud. Peru’s free national mental-health line, in Spanish: call 113 and choose option 5.

References

1. Garcia-Argibay M, Chang Z, Brikell I, et al. Evaluating ADHD medication trial representativeness: a Swedish population-based study comparing hypothetically trial-eligible and trial-ineligible individuals. Lancet Psychiatry. 2025;12(2):131-139. doi:10.1016/S2215-0366(24)00396-1
2. Kooij JJS, Bijlenga D, Salerno L, et al. Updated European Consensus Statement on diagnosis and treatment of adult ADHD. Eur Psychiatry. 2019;56:14-34. doi:10.1016/j.eurpsy.2018.11.001
3. National Institute for Health and Care Excellence. Attention deficit hyperactivity disorder: diagnosis and management (NG87). London: NICE; 2018 (updated 2019).
4. Faraone SV, Banaschewski T, Coghill D, et al. The World Federation of ADHD International Consensus Statement: 208 evidence-based conclusions about the disorder. Neurosci Biobehav Rev. 2021;128:789-818. doi:10.1016/j.neubiorev.2021.01.022