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April 23, 2025
Background:
Stimulants, such as methylphenidate and amphetamines, are currently considered effective medications for treating ADHD. However, approximately one-third of patients do not have an adequate response to these treatments. Additionally, long-term adherence is relatively low, with only about half of the patients still using methylphenidate after six years.
Recently, there has been increasing attention to the concept of microdosing with psychedelic drugs such as psilocybin and LSD. A microdose typically ranges from one-tenth to one-twentieth of a recreational dose and does not produce noticeable perceptual effects or interfere with daily activities.
The Study:
A European research team recently published the findings of the first double-blind, placebo-controlled randomized clinical trial examining the safety and efficacy of repeated low doses of LSD in adults diagnosed with ADHD.
The six-week trial took place at University Hospital in Basel, Switzerland, and Maastricht University, Netherlands. Participants, aged 18 to 65, had clinical diagnoses of ADHD with moderate to severe symptoms.
The team excluded persons with a past or present diagnosis of psychotic disorders, substance use disorders, or other psychiatric or somatic disorders likely to require hospitalization or treatments.
Participants were randomly assigned in a 1:1 ratio to receive either LSD or placebo. Neither study staff nor participants were aware of the assignments until the conclusion of the trial.
During the six-week trial, participants received twice-weekly doses on-site, amounting to a total of 12 doses. Following the first and final doses, participants were asked to determine whether they had been administered LSD or a placebo in order to assess blinding. Four weeks after the conclusion of the microdosing period, participants returned for an evaluation of the treatment's safety and efficacy.
Twenty-seven of the 53 participants were randomized to receive the LSD microdosing treatment in a liquid solution, and 26 to receive placebo. Placebo consisted of the same drinking solution, minus the microdose of LSD.
The average age was 37, and 42% of participants were female. Forty-six of the 53 participants completed the study.
Out of 29 participants, 21 from the LSD group and eight from the placebo group correctly guessed their allocation, totaling 63% overall.
As assessed through the Adult ADHD Investigator Symptom Rating Scale, ADHD symptoms improved by 7.1 points in the LSD group and 8.9 points in the placebo group, with no significant difference between them.
Regarding safety, the LSD group experienced nearly double the adverse events compared to the placebo group. None of the events in either group were classified as serious. The five most frequent adverse events were headache, nausea, fatigue, insomnia, and visual alterations, occurring around three times more frequently in the LSD group than in the placebo group.
The team concluded, “although repeated low-dose LSD administration was safe in an outpatient setting, it failed to demonstrate efficacy compared with placebo in improving ADHD symptoms among adults.”
Conclusion: Microdosing with LSD did not offer significant advantages over placebo in treating ADHD symptoms, despite being physically safe and well tolerated in the trial setting. This suggests that further research is needed to explore alternative treatments for ADHD.
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Lorenz Mueller, Joyce Santos de Jesus, Yasmin Schmid, Felix Müller, Anna Becker, Aaron Klaiber, Isabelle Straumann, Dino Luethi, Eline C. H. M. Haijen, Petra P. M. Hurks, Kim P. C. Kuypers, and Matthias E. Liechti, “Safety and Efficacy of Repeated Low-Dose LSD for ADHD Treatment in Adults: A Randomized Clinical Trial,” JAMA Psychiatry (2025), https://doi.org/10.1001/jamapsychiatry.2025.0044.
The Background:
Previous research has suggested that people with ADHD have higher rates of death than those without the condition. Until now, many of those studies lacked the detail needed to untangle why this might be the case. A recent meta-analysis of eight separate studies reported that ADHD roughly doubled the risk of death, and it hinted that factors like socioeconomic status and other mental illnesses might help explain the link.
The Study:
To explore this in more detail, researchers used the US National Health Interview Survey, a nationally representative prospective cohort of just over 52,000 adults. Survey records were linked with the National Death Index, and participants were followed from the date of interview until death or December 31, 2019, whichever came first. The main outcome was death from any cause. With a median follow-up of just under eight years, there were 6,024 deaths recorded.
When the team adjusted their analysis for age, sex, ethnicity, and the year of the survey, having ADHD was associated with a 58% higher risk of death. Controlling further for family income and educational level reduced that increased risk slightly, to 50%.
Controlling for health conditions (like high blood pressure, diabetes, stroke, heart disease, and cancer) and lifestyle factors (smoking, alcohol use, physical activity, and body weight) also reduced the association to about 46%.
By contrast, when the researchers adjusted for two psychiatric conditions (anxiety and depression) commonly found alongside ADHD, the link between ADHD and higher mortality disappeared statistically. In other words, once anxiety and depression were taken into account, ADHD itself was no longer associated with a clearly measurable increase in the risk of death.
What Does This Mean?
The authors conclude that the apparent effect of ADHD on mortality seems to operate largely through accompanying mental illness, and to a lesser extent through lifestyle and physical health problems. They suggest that treating and managing these co-occurring issues (through medications, therapy, and behavioral interventions) might help reduce the risk of premature death in people with ADHD, although they note that further evidence is needed.
The Background:
Dementia is a rapidly growing public health problem affecting more than 50 million people worldwide. Nearly 10 million new cases are diagnosed each year, and that number is expected to almost triple by 2050. The most common form is Alzheimer’s disease, accounting for roughly 60–70% of cases, followed by vascular dementia at around 20%. Other types include dementia with Lewy bodies, Parkinson’s disease dementia, and frontotemporal dementia. While no cure exists, managing modifiable risk factors (such as high blood pressure, smoking, physical inactivity, and poorly controlled diabetes) can delay or slow both the onset and progression of the condition.
Several studies have reported an elevated dementia risk among people with ADHD, and a number of mechanisms may explain this association. These include shared genetic or neurobiological vulnerabilities, reduced cognitive reserve (leaving the brain less resilient to age-related damage), and greater lifetime exposure to other established dementia risk factors.
Earlier reviews explored the possible link between ADHD and dementia, but tended toward a broader scope (incorporating other neurodegenerative disorders or mixing study designs), which introduced substantial variability and precluded quantitative synthesis. The relevant research literature has also expanded considerably since those reviews appeared.
The Study:
This meta-analysis restricted inclusion to case-control and cohort studies, yielding five that met the criteria. One was a case-control study with 400 participants; the other four were cohort studies collectively covering 3.7 million individuals, two retrospective and two prospective.
The Results:
Pooling the four cohort studies, individuals with ADHD showed approximately two-and-a-half times the dementia risk of those without the diagnosis. There was no indication of publication bias.
The Take-Away:
The authors concluded that ADHD is associated with a significantly increased risk of all-cause dementia in later life, while noting that its relationship to specific dementia subtypes remains less clear and warrants attention in future research.
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The Background:
Women with polycystic ovary syndrome (PCOS) themselves show higher rates of ADHD. Because ADHD is partly heritable (meaning genes contribute to the condition), some of the increased ADHD seen in children of mothers with PCOS could come from shared genetic factors. In other words, a mother’s and her child’s increased risk might sometimes reflect common genes rather than an effect of the pregnancy itself.
Beyond genetics, growing evidence points to maternal metabolic problems during pregnancy as another important risk factor for neurodevelopmental outcomes. PCOS is one of these conditions and is considered both potentially modifiable (treatable or manageable) and biologically plausible as a contributor to risk. PCOS affects an estimated 5–10% of women of reproductive age worldwide and is characterized by signs such as hyperandrogenism (higher-than-normal levels of “male” hormones), insulin resistance (poorer ability to use the hormone insulin, which can affect blood sugar and metabolism), and chronic low-grade inflammation.
However, studies to date have not all reached the same conclusions. Some research suggests the association between maternal PCOS and offspring ADHD is stronger for girls, while other studies did not analyze results by child sex. Methodological differences make it harder to draw clear conclusions.
The Study:
It’s important to note that the studies included in this meta-analysis were observational (cohort studies and case-control studies). Observational studies can identify associations (that two things occur together) but cannot prove that one causes the other. A cohort study follows people over time, and a case-control study compares people with a condition to similar people without it.
The pooled results came from six studies that together included almost 1.4 million mother–child pairs and that adjusted for confounders (other factors that might influence the result, such as maternal age or socioeconomic status). After statistical adjustment, children of mothers with PCOS had about 40% greater odds of ADHD than children of mothers without PCOS. The analysis reported no evidence of publication bias (no clear sign that only positive studies were published) and zero heterogeneity (the results were consistent across the studies).
There was no meaningful difference in results between cohort and case-control studies, and the meta-analysis did not find a significant difference in the association when comparing male and female offspring.
The Take-Away:
The research team concluded that this large-scale synthesis found an association between maternal PCOS and higher odds of ADHD and other neuropsychiatric conditions in children. They suggested that children born to mothers with PCOS may benefit from developmental monitoring to identify and address problems early, while emphasizing that causal relationships have not been established. They called for further studies to confirm these findings and to investigate the biological and environmental mechanisms that might explain the association. Indeed, because women with PCOS show higher rates of ADHD than other women, we need genetically informed research designs to see if the reported association is confounded.
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