The 'Medication Tolerance' Myth in ADHD: What the Evidence Actually Says

For years, a persistent concern has shadowed the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD): Does the medication eventually stop working? Patients often report that their symptoms seem to return despite consistent use, leading to "dose escalation" or "medication holidays." A new systematic review from Sam Cortese’s team  published in CNS Drugs finally puts these concerns to the test by synthesizing decades of empirical research.

Before diving into the findings, you must understand two often-confused phenomena:

  • Tachyphylaxis (Acute Tolerance): A rapid decrease in response to a drug, often occurring within a single day (24 hours).
  • Tolerance: A gradual reduction in responsiveness over long-term exposure, requiring higher doses to achieve the original effect.

The review analyzed 17 studies covering over 10,000 individuals, and the results provide a much-needed reality check for the clinical community.

The researchers found preliminary evidence that acute tolerance (tachyphylaxis) can occur within a 24-hour window.

  • Subjective Effects: Studies showed that "drug liking" or feelings of euphoria from stimulants often peak and fade faster than the actual drug concentration in the blood.
  • Clinical Impact: This phenomenon is why some older, flat-release formulations were less effective than modern "ascending" delivery systems (like OROS-methylphenidate), which are designed to overcome this daily dip in efficacy.

The most important finding is that tolerance does not commonly develop to the therapeutic effects of ADHD medication in the long term. In one landmark study following children for up to 10 years, only 2.7% of participants lost their response to methylphenidate without a clear external explanation.  Doses, when adjusted for natural body growth, remained remarkably stable over years of treatment.

Consistent with the lack of therapeutic tolerance, the body does not become tolerant to the physical side effects of stimulants.  Increases in heart rate and blood pressure typically persist for as long as the medication is taken.  This underscores why clinicians must continue monitoring cardiovascular health throughout the entire duration of treatment.

If it’s Not Tolerance, What Is It?

If "tolerance" isn't real, why do some patients feel their medication is failing? The review suggests clinicians look at these alternative explanations:

  1. Natural Symptom Fluctuations: ADHD is not a static condition; symptoms naturally wax and wane over time regardless of treatment.
  2. Limited Compliance: Missed doses or inconsistent timing are often the real culprits behind "failing" efficacy.
  3. Life Events & Transitions: New jobs, academic pressures, or stressful life changes can increase the "functional demand" on a patient, making their current dose feel insufficient.
  4. Co-occurring Conditions: The emergence of anxiety, depression, or substance use disorders can mask or mimic a return of ADHD symptoms.

Why This Matters

These results provide clinicians the confidence to tell patients that their medication is unlikely to "wear out" permanently. Rather than immediately increasing a dose when symptoms flare, the first step should be a "clinical deep dive" into the patient's lifestyle, stress levels, and adherence.

For researchers, the review highlights a major gap: most existing studies are small, dated, or of low quality. There is a dire need for robust, longitudinal studies that track both the brain's response and the patient's environment over several years.

For people with ADHD, while your body might get "used to" the initial "buzz" of a stimulant within hours, its ability to help you focus and manage your life remains remarkably durable over the years.

Smith, C., Walker, H., Parlatini, V., & Cortese, S. (2026). Tolerance and tachyphylaxis to medications for attention-deficit/hyperactivity disorder (ADHD): A systematic review of empirical studies. CNS Drugs. . https://doi.org/10.1007/s40263-025-01263-8

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Unmedicated Adult ADHD Linked to Dementia in Population Study

Background:

Noting that “the association between adult ADHD and dementia risk remains a topic of interest because of inconsistent results,” an Israeli study team tracked 109,218 members of a nonprofit Israeli health maintenance organization born between 1933 and 1952 who entered the cohort on January 1, 2003, without an ADHD or dementia diagnosis and were followed up to February 28, 2020. 

Israeli law forbids nonprofit HMOs from turning anyone away based on demographic factors,  health conditions, or medication needs, thereby limiting sample selection bias.  

The estimated prevalence of dementia in this HMO, as diagnosed by geriatricians, neurologists, or psychiatrists, is 6.6%. This closely matches estimates in Western Europe (6.9%) and the United States (6.5%). 

Method:

The team considered, and adjusted for, numerous covariates: age, sex, socioeconomic status, smoking, depression, obesity, chronic obstructive pulmonary disease, hypertension, atrial fibrillation, heart failure, ischemic heart disease, cerebrovascular disease, diabetes, Parkinson’s disease, traumatic brain injury, migraine, mild cognitive impairment, psychostimulants. 

With these adjustments, individuals diagnosed with ADHD were almost three times as likely to be subsequently diagnosed with dementia as those without ADHD. Men with ADHD were two and a half times more likely to be diagnosed with dementia, whereas women with ADHD were over three times more likely, than non-ADHD peers. 

More concerning still, persons with ADHD were 5.5 times more likely to be subsequently diagnosed with early onset dementia, as opposed to 2.4 times more likely to be diagnosed with late onset dementia. 

On the other hand, the team found no significant difference in rates of dementia between individuals with ADHD who were being treated with stimulant medications and individuals without ADHD. Those with untreated ADHD had three times the rate of dementia. The team nevertheless cautioned, “Due to the underdiagnosis of dementia as well as bidirectional misdiagnosis, this association requires further study before causal inference is plausible.” 

Conclusions and Relevance:

This study reinforces existing evidence that adult ADHD is associated with an increased risk of dementia. Notably, the increased risk was not observed in individuals receiving psychostimulant medication, however the mechanism behind this association is not clear.

These findings underscore the importance of reliable ADHD assessment and management in adulthood. They also highlight the need for further study into the link between stimulant medications and the decreased risk of dementia.

 

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February 25, 2025

ADHD medication and risk of suicide

ADHD Medication and Risk of Suicide

A Chinese research team performed two types of meta-analyses to compare the risk of suicide for ADHD patients taking ADHD medication as opposed to those not taking medication.

The first type of meta-analysis combined six large population studies with a total of over 4.7 million participants. These were located on three continents - Europe, Asia, and North America - and more specifically Sweden, England, Taiwan, and the United States.

The risk of suicide among those taking medication was found to be about a quarter less than for unmediated individuals, though the results were barely significant at the 95 percent confidence level (p = 0.49, just a sliver below the p = 0.5 cutoff point). There were no significant differences between males and females, except that looking only at males or females reduced sample size and made results non-significant.

Differentiating between patients receiving stimulant and non-stimulant medications produced divergent outcomes. A meta-analysis of four population studies covering almost 900,000 individuals found stimulant medications to be associated with a 28 percent reduced risk of suicide. On the other hand, a meta-analysis of three studies with over 62,000 individuals found no significant difference in suicide risk for non-stimulant medications. The benefit, therefore, seems limited to stimulant medication.

The second type of meta-analysis combined three within-individual studies with over 3.9 million persons in the United States, China, and Sweden. The risk of suicide among those taking medication was found to be almost a third less than for unmediated individuals, though the results were again barely significant at the 95 percent confidence level (p =0.49, just a sliver below the p = 0.5 cutoff point). Once again, there were no significant differences between males and females, except that looking only at males or females reduced the sample size and made results non-significant.

Differentiating between patients receiving stimulant and non-stimulant medications once again produced divergent outcomes. Meta-analysis of the same three studies found a 25 percent reduced risk of suicide among those taking stimulant medications. But as in the population studies, a meta-analysis of two studies with over 3.9 million persons found no reduction in risk among those taking non-stimulant medications.

A further meta-analysis of two studies with 3.9 million persons found no reduction in suicide risk among persons taking ADHD medications for 90 days or less, "revealing the importance of duration and adherence to medication in all individuals prescribed stimulants for ADHD."

The authors concluded, "exposure to non-stimulants is not associated with a higher risk of suicide attempts. However, a lower risk of suicide attempts was observed for stimulant drugs. However, the results must be interpreted with caution due to the evidence of heterogeneity ..."

December 13, 2021

Does ADHD Medication Improve the Parenting Skills of Adults with ADHD?

Does ADHD Medication Improve the Parenting Skills of Adults with ADHD?

Raising children is not easy. I should know.

As a clinical psychologist, I've helped parents learn the skills they need to be better parents. And my experience raising three children confirmed my clinical experience.

Parenting is a tough job under the best of circumstances, but it is even harder if the parent has ADHD.

For example, an effective parent establishes rules and enforces them systematically. This requires attention to detail, self-control, and good organizational skills. Given these requirements, it is easy to see how ADHD symptoms interfere with parenting. These observations have led some of my colleagues to test the theory that treating ADHD adults with medication would improve their parenting skills. I know about two studies that tested this idea.

In 2008, Dr. Chronis-Toscano and colleagues published a study using a sustained-release form of methylphenidate for mothers with ADHD. As expected, the medication decreased their symptoms of inattention and hyperactivity/impulsivity. The medication also reduced the mother's use of inconsistent discipline and corporal punishment and improved their monitoring and supervision of their children.

In a 2014 study, Waxmonsky and colleagues observed ADHD adults and their children in a laboratory setting once when the adults were off medication and once when they were on medication. They used the same sustained-release form of amphetamine for all the patients. As expected, the medications reduced ADHD symptoms in the parents. This laboratory study is especially informative because the researchers made objective ratings of parent-child interactions, rather than relying on the parents' reports of those interactions. Twenty parents completed the study. The medication led to less negative talk and commands and more praise by parents. It also reduced negative and inappropriate behaviors in their children.

Both studies suggest that treating ADHD adults with medication will improve their parenting skills. That is good news. But they also found that not all parenting behaviors improved. That makes sense. Parenting is a skill that must be learned. Because ADHD interferes with learning, parents with the disorder need time to learn these skills. Medication can eliminate some of the worst behaviors, but doctors should also provide adjunct behavioral or cognitive-behavioral therapies that could help ADHD parents learn parenting skills and achieve their full potential as parents.

May 7, 2021

New Expert Guidance on "Deprescribing" Stimulants for Adults with ADHD

The Background: 

Over the past two decades, diagnostic rates for adult ADHD have roughly doubled, and stimulant prescriptions in the United States skyrocketed by more than 50% between 2012 and 2023, particularly among girls and women. While these medications help many individuals manage their symptoms, a landmark 2026 article published in European Neuropsychopharmacology tackles an important question that is rarely discussed: When should doctors and patients consider stopping them?  

The Discussion: 

To answer this, the American Society of Clinical Psychopharmacology (ASCP) gathered a task force of 45 international experts spanning 12 countries. Through a rigorous evaluation process, they reached an overwhelming agreement on a framework for "deprescribing", the planned, supervised reduction or cessation of a medication. Here are the core insights from these ground-breaking guidelines and what they mean for adults navigating long-term ADHD treatment.  

When the Treatment Isn’t Yielding Benefits 

One of the most straightforward reasons to consider stopping a stimulant is if it simply isn’t doing its job. The task force agreed that if a patient does not experience an optimal response, measured by actual symptom reduction, improved daily functioning, and a better quality of life, even after trying a high, optimized dose, it may be time to step back and look at alternative options.  

Sometimes, the issue goes back to the initial evaluation. The criteria for diagnosing ADHD have expanded over the years, and brief psychiatric evaluations can occasionally lead to diagnostic inaccuracies. If a thorough reevaluation reveals that the original ADHD diagnosis was incorrect, the expert consensus is clear: stimulant deprescribing is appropriate unless another stimulant-responsive condition is evident. Furthermore, if a patient develops a persistent tolerance to the drug that cannot be resolved by safe dose adjustments, a temporary taper or drug holiday may be recommended.  

When the Risks to Health Outweigh the Rewards 

Our bodies and health needs naturally shift over time, meaning a medication that worked safely years ago might pose a threat to your health today. The experts concluded that deprescribing should be heavily considered if stimulants exacerbate a concurrent medical or psychiatric illness. For example, although rare, stimulants can unintentionally trigger mania or psychosis in adults with unstable or unrecognized comorbid bipolar disorder.  

Physical health developments are equally critical. If an adult develops a newly arising or unstable cardiovascular condition, such as a cardiac arrhythmia, ischemia, or cardiomyopathy, the risk-benefit balance changes dramatically. Additionally, if severe side effects occur that cannot be managed by reducing the dosage, or if dangerous new drug-drug interactions emerge, stopping the medication under medical supervision protects the patient's long-term well-being.  

Addressing Misuse and the Complex Role of Cannabis 

Because stimulant medications target brain reward and wakefulness circuitry, they can foster a propensity for misuse. Studies indicate that more than 1 in 5 adults prescribed stimulants have misused them, and 1 in 6 have diverted their medication to others. The task force emphasizes that deprescribing is warranted if a patient persistently takes doses higher than prescribed against medical advice, uses the medication purely for unauthorized performance enhancement, or has an untreated, coexisting substance use disorder.  

And what about cannabis? This topic sparked the most debate among the experts, falling just short of an official consensus with 71% agreement that regular cannabis use alone shouldn't automatically trigger a stimulant stoppage. Recognizing the complexity, such as how chronic cannabis use can overlap with ADHD executive function deficits, the task force proposed a structured monitoring approach instead of an immediate cutoff. Clinicians are encouraged to track the patient every 1 to 3 months using standardized symptom tools and random urine drug screens to verify whether cannabis use is actively neutralizing the stimulant's therapeutic benefits.  

The Path Forward: Safe Tapering and Lifestyle Support 

If you and your doctor decide that stopping a stimulant is the right path, it shouldn’t happen overnight. The task force strongly recommends that medications be gradually tapered off at a rate tailored to the individual to minimize potential disruptions and distinguish between transient withdrawal and a true return of ADHD symptoms.  

Crucially, stopping a medication doesn't mean stopping treatment. The experts highlight that the success of any deprescribing plan is significantly enhanced when patients focus on optimizing modifiable lifestyle factors. Prioritizing sleep hygiene, staying physically active, and implementing structured behavioral strategies can support executive functioning and help sustain your cognitive gains even as the medication is reduced or eliminated.  

The Takeaway: 

The decision to continue or stop an ADHD medication is a deeply personal one that requires balancing real-world efficacy, safety, and individual health changes. These new consensus recommendations provide an essential roadmap to help adults navigate their long-term mental health journeys safely and effectively.  

Are you or a loved one currently evaluating your long-term relationship with ADHD medication? Consider scheduling a check-in with your healthcare provider to discuss whether your current treatment plan still perfectly matches your health needs today. 

ADHD and Health: How Sex Differences Impact Physical Health into Adulthood

Girls are diagnosed with ADHD at less than half the rate of boys, but this gap closes significantly by adulthood. ADHD also looks different in females than in males, with distinct patterns in symptoms, development, functional impairment, economic impact, and long-term outcomes. Despite this, sex differences in how ADHD relates to physical health have been poorly studied. 

Prior research has established that both children and adults with ADHD face elevated risk for a range of physical health conditions. But that work has been hampered by small samples, retrospective designs, and limited population coverage. 

The Study

Denmark's single-payer national health system makes it possible to conduct truly population-wide research. This study drew on Danish national registers to follow more than 825,000 individuals, born between 1984 and 1995, from birth through adolescence and into young adulthood, tracking them across 13 categories of physical disease. Only individuals free of a relevant physical diagnosis at birth were included, and ADHD diagnosis was treated as something that could be acquired over time rather than a fixed characteristic. 

The Results: 

Across both sexes, people diagnosed with ADHD consistently showed higher disease risk than the general population, with cancer being the one notable exception. The absence of a meaningful cancer signal is expected, given that cancer predominantly affects older age groups than those captured in this study. 

For most other disease categories (including infectious, endocrine, metabolic, respiratory, digestive, musculoskeletal, and genitourinary diseases), elevated risk emerged in early adolescence. For the remaining categories, elevated risk was present at all ages studied. 

The magnitude of these risks was often substantial: 

  • Infectious diseases: Males aged 14–23 with ADHD faced about 20% greater risk than peers without ADHD; females in the same age group faced roughly 80% greater risk. These differences converged to around 45% above baseline beyond that age. 
  • Eye diseases: Before age 11, males with ADHD had more than twice the risk of their non-ADHD peers; females had more than five times the risk. By age 22, both sexes converged at roughly 35% above baseline. 
  • Ear diseases: Risk was more than five times higher in children with ADHD under age 7. 
  • Nervous system diseases: Risk more than doubled across all ages studied. 
  • Endocrine, nutritional, and metabolic diseases: Risk more than doubled between ages 7 and 23. 
  • Skin conditions: Risk more than doubled through age 11. 

By early adulthood, individuals with ADHD showed at least 20% greater risk across every disease category except cancer, regardless of sex. 

Sex Differences Shift With Age 

One of the study's more nuanced findings concerns how sex interacts with ADHD diagnosis over time. In the general population, females tend to have higher physical disease risk from the teenage years onward, while males show higher risk in early childhood. ADHD diagnosis disrupted these patterns unevenly, amplifying risk in some groups and age windows more than others. 

Perhaps most notably, the transition into young adulthood appeared to reduce the ADHD-associated gap between the sexes for endocrine, nutritional, and metabolic diseases (from a ninefold female-to-male disparity down to roughly 4.5-fold). The authors suggest this may reflect ADHD's influence on sex hormone activity during this developmental period. 

Takeaway 

This large, population-representative study confirms that an ADHD diagnosis is associated with meaningfully elevated risk across nearly all categories of physical disease, and that this relationship is neither uniform across sexes nor static across the lifespan. The findings underscore the need for sex-sensitive, developmentally informed approaches to the physical healthcare of people with ADHD. 

Antidepressants in Pregnancy and ADHD Risk: What a Major New Analysis Found

Antidepressants are the primary drug treatment for depressive disorders, which affect 15–20% of pregnant women. They are among the most widely prescribed medications worldwide, and their use has increased in recent decades. Understanding their reproductive safety is critical to support informed, evidence-based prescribing during pregnancy. 

A new meta-analysis sheds important light on one of the most debated concerns: whether children born to mothers who took antidepressants during pregnancy face a higher risk of ADHD. 

The Study: 

Pooling 14 studies covering more than 14 million participants, the analysis found that prenatal antidepressant exposure was associated with a 35% higher rate of ADHD in offspring compared to no exposure. A separate look at SSRIs (the most widely prescribed class of antidepressants, including Prozac and Zoloft) across 11 studies and over four million pregnancies found an even higher apparent risk (44%)  after correcting for publication bias. On the surface, these are striking numbers. 

Both associations came with an important caveat: enormous variation between individual studies, a statistical red flag suggesting the results may not reflect a true underlying effect. More tellingly, the apparent risk evaporated entirely when researchers applied a more rigorous method — comparing siblings within the same family, where one child was exposed to antidepressants in the womb, and another was not. 

This sibling-comparison design is particularly powerful because it automatically controls for factors that run in families: shared genes, household environment, parenting, and socioeconomic conditions. When those influences are held constant, the link between antidepressant exposure and ADHD disappears. The same pattern held for SSRIs specifically. 

Two other antidepressant classes, SNRIs (serotonin norepinephrine reuptake inhibitors) and tricyclics, showed no significant association in any analysis. 

“Confounding by Indication”: 

The probable driver of the initial association is what researchers call confounding by indication. The very condition being treated (depression) is itself a risk factor for ADHD in offspring, independently of any medication. Mothers with more severe depression are also more likely to be prescribed antidepressants, meaning the drug and the underlying illness are difficult to disentangle in standard analyses. Sibling studies cut through this problem cleanly. 

The Take-Away: 

The authors concluded that the association between antidepressants and ADHD risk was non-significant across all analyses designed to account for these confounding factors. This doesn’t mean antidepressants are without any reproductive considerations, but it does suggest that ADHD risk, at least, is driven by heritable and family-level factors rather than medication exposure itself. 

For clinicians and patients weighing the risks of treating or not treating depression during pregnancy, this distinction matters considerably.