Atomoxetine Increased Effect over Time in Adults with Attention-Deficit/Hyperactivity Disorder Treated for up to 6 Months: Pooled Analysis of Two Double-Blind, Placebo-Controlled, Randomized Trials

Current nonstimulant medications for adults with attention-deficit/hyperactivity disorder

INTRODUCTION

Stimulants, including methylphenidate and amphetamines, are the first-line pharmacological treatment of ADHD in adults. However, in patients who do not respond or poorly tolerate stimulants, non-stimulant medications are usually recommended.

AREAS COVERED

The authors provide a narrative review of the literature on non-stimulant treatments for adult ADHD, including controlled and observational clinical studies conducted on adult samples. Atomoxetine has been extensively studied and showed significant efficacy in treating adult ADHD. Issues related to dosing, treatment duration, safety, and use in the case of psychiatric comorbidity are summarized. Among other compounds indicated for ADHD in adults, antidepressants sharing at least a noradrenergic or dopaminergic component, including tricyclic compounds, bupropion, and viloxazine, have shown demonstratable efficacy. Evidence is also available for antihypertensives, particularly guanfacine, as well as memantine, metadoxine, and mood stabilizers, while negative findings have emerged for galantamine, antipsychotics, and cannabinoids.

EXPERT OPINION

While according to clinical guidelines, atomoxetine may serve as the only second-line option in adults with ADHD, several other nonstimulant compounds may be effectively used in order to personalize treatment based on comorbid conditions and ADHD features. Nevertheless, further research is needed to identify and test more personalized treatment strategies for adults with ADHD.

Recommendation for Long-term Management of Adult Attention-Deficit/Hyperactivity Disorder in Military Populations, Veterans, and Dependents: A Narrative Review

INTRODUCTION

In addition to the higher burden of mental health disease in the military, there is a compounding antecedent association between behavioral health comorbidities and the treatment of attention-deficit/hyperactivity disorder (ADHD) in this population. Despite the low prevalence of new-onset ADHD in adults globally, the rate of stimulant (i.e., amphetamines) prescription is increasing. Stimulants can exacerbate mental health disease (often masquerading as ADHD symptomatology), precluding optimal treatment of the underlying etiology and imposing unnecessary dangerous side effects. This study aimed to evaluate the long-term safety and efficacy of stimulants for managing adult ADHD.

METHODS

A nine-member multidisciplinary team reviewed a PubMed search with the terms "adult," "ADHD," and "stimulant." Targeted PubMed and Google Scholar searches for "adult ADHD" paired with Food and Drug Administration -approved ADHD medications and Google Scholar literature using forward and reverse snowballing methods were performed for high-quality studies focusing on long-term treatment in ADHD. An evidence table and clinical algorithm were developed from the review.

RESULTS

Of the 1,039 results, 50 articles were fully reviewed, consisting of 21 descriptive and experimental studies, 18 observational, and 11 systematic reviews and meta-analyses. Illustrative cases within the structured discussion of the results highlighted ADHD and psychiatric comorbidities, risks, harms, and benefits of stimulant use, medication mechanisms of action, and limitations of the current evidence.

DISCUSSION

The dearth of high-quality studies on long-term ADHD management in adults fails to establish a causal relationship between stimulant use and physiological harm. Despite mixed evidence supporting the benefit of stimulants, there is clear evidence regarding the risk of harm. The serious risks of stimulants include arrhythmias, myocardial infarction, stroke/transient ischemic attack, sudden death, psychosis, and worsening of behavioral health disease. Additionally, there is a possible long-term risk of harm due to chronic sympathetic load (i.e., cardiovascular system remodeling). Stimulants pose a greater risk for addiction and abuse compared to other evidence-based nonstimulant medications that have similar effectiveness. Both stimulants and nonstimulants might promote favorable neuroanatomical changes for long-term improvement of ADHD symptoms, but nonstimulants (atomoxetine) have the pharmacological advantage of also mitigating the effects of sympathetic load (sympatholysis) and anxiety (anxiolysis). Given the physiological uncertainty of extended stimulant use for adults, especially older adults with vulnerable cardiovascular systems, clinicians should proceed cautiously when considering initiating or sustaining stimulant therapy. For long-term treatment of ADHD in adults, clinicians should consider nonstimulant alternatives (including behavioral therapy) due to the comparatively lower side effect risk and the possible additional benefit in patients with behavioral health comorbidities.

CONCLUSION

Long-term safety of stimulant use for adults with ADHD is uncertain, as existing studies are limited in quality and duration. This is particularly important for military populations with higher rates of mental health conditions. Managing ADHD and related conditions requires prioritizing cardiovascular safety, especially for older adults. Nonstimulant options can be helpful, especially in comorbid psychiatric disease. Before treating ADHD, ruling out and controlling other behavioral health conditions is essential to avoid masking or worsening underlying issues and reducing unnecessary medication side effects.

Relationship between two forms of impulsivity in mice at baseline and under acute and sub-chronic atomoxetine treatment

RATIONALE

Impulsivity is a symptom of various mental disorders, including attention deficit hyperactivity disorder (ADHD), bipolar disorder, and addiction. Impulsivity is not a unitary construct, but is present in different forms, yet only a few rodent studies have explored the relationship between these forms within individual subjects.

OBJECTIVES

In this study, we compared behaviors representing two impulsivity forms, delay discounting (choice impulsivity) and premature responding (waiting impulsivity), within the same mice.

METHODS

C57BL/6J male mice were concurrently trained and tested in the delay discounting task and the rodent continuous performance test in a counterbalanced design. The effects of the ADHD medication atomoxetine were tested in both tasks, after both acute (0.3-5.0 mg/kg) and sub-chronic (0.3 mg/kg twice daily for seven days) administration.

RESULTS

There was no correlation between the two impulsivity forms at baseline. Acute atomoxetine treatment (1, 3, and 5 mg/kg) significantly reduced premature responding. Furthermore, sub-chronic treatment with 0.3 mg/kg of atomoxetine caused a stable decrease in premature responding. Atomoxetine had no significant effect on delay discounting after acute or sub-chronic administration, although the acute administration of 1 mg/kg showed a trend towards increasing delay discounting.

CONCLUSIONS

The present results support that delay discounting and premature responding represent two different forms of impulsivity that show dissimilar responses to atomoxetine treatment. The consistency with findings in humans lends support to the translatability of the results in mice.

Long-term treatment of adult ADHD in a naturalistic setting: clinical predictors of attrition, medication choice, improvement, and response

Objectives: The aim of this study was to identify clinical predictors of treatment attrition, medication choice, improvement and response to pharmacotherapy in adult attention-deficit/hyperactivity disorder (ADHD). Methods: 150 ADHD patients were enrolled and naturalistically followed-up for at least 4 months. Conners' Adult ADHD Rating Scales-Observer: Screening Version (CAARS-O:SV) were used to measure ADHD severity. Results: 58 subjects (38.7%) were lost at follow-up, while 75 (50%) completed follow-up assessment, on average after 26.05 ± 11.99 weeks; 35 were treated with atomoxetine (ATX) and 40 with methylphenidate (MPH). Treatments were moderately effective (d = 0.72) and 37 patients (49.3%) were responders (≥30% CAARS-O:SV decrease). Patients lost at follow-up had lower inattentive symptoms, less generalized anxiety and family history of bipolar disorder, more amphetamine use disorder than follow-up completers. Compared to ATX-treated subjects, MPH-treated patients had greater severity of hyperactivity/impulsivity and were more frequently diagnosed with alcohol use disorder. While MPH and ATX showed similar efficacy, more pronounced improvements were observed in patients with combined ADHD, anxiety and substance use disorders. ADHD severity and comorbid substance use positively predicted response. Conclusions: Consensus-based hierarchical treatment of ADHD comorbidity is not consistently supported. Comorbid anxiety, mood and substance use disorders should not discourage the treatment of adult ADHD.

Identification of factors associated with the efficacy of atomoxetine in adult attention-deficit/hyperactivity disorder

Aim

Atomoxetine (ATX) is a non‐central stimulant and a standard treatment for adult attention‐deficit/hyperactivity disorder (ADHD). The long‐term efficacy of Atomoxetine is about 40% at 6 months. The variability in efficacy between individuals is thought to be related to patient‐specific factors, but no detailed research has been conducted. In this retrospective cohort study, we aimed to identify the factors associated with Atomoxetine efficacy.

Methods

A total of 147 patients with attention‐deficit/hyperactivity disorder aged ≥18 years who were using Atomoxetine for the first time were included in this study. The outcome was treatment success (treatment maintained for at least 6 months and improvement in symptoms). Symptom assessment was based on the overall improvement in symptoms judged by an expert physician.

Results

Of the patient sample, 103 (70.1%) achieved the outcome. Logistic regression analysis identified “the maximum dose of ATX” and “gambling habit” as factors associated with efficacy ( P  < 0.05). In the process of Atomoxetine titration, the larger the maximum dose, the higher the efficacy was shown to be. Gambling habits may be indicative of impulsivity, which is among the core symptoms of attention‐deficit/hyperactivity disorder. Thus, a gambling habit may be considered a surrogate marker for impulsivity.

Conclusions

Knowledge of these factors will help healthcare professionals to predict the likely efficacy of Atomoxetine in a given patient before subscribing it, facilitating individualized pharmacotherapy for adult attention‐deficit/hyperactivity disorder.

We retrospectively examined factors associated with the efficacy of atomoxetine for adult ADHD. The maximum dose of atomoxetine and gambling habit were identified as significant factors related to the efficacy.

Clinical Impact of Not Achieving Recommended Dose on Duration of Atomoxetine Treatment in Adults with Attention-Deficit/Hyperactivity Disorder

Aim

To compare atomoxetine (ATX) length of therapy (LoT) among adults with ADHD who reached the recommended dose of 80 mg/day (ATX ≥ 80) versus those who did not (ATX < 80) analyzed separately in patients prescribed ATX as monotherapy (mono) and in combination with other ADHD medications (combo).

Methods

This was a retrospective observational cohort study of the Truven Health Marketscan Commercial Claims Database from January 1, 2006–September 30, 2013, with a 6‐month preindex period free of ATX (1st ATX claim as index event) and a 1‐year follow‐up. LoT during follow‐up was calculated using prescription claim fill dates and included all days with medication on hand regardless of treatment gaps.

Results

Only 45.0% of the 36,076 mono and 77.9% of the 1548 combo patients reached an ATX dose of ≥80 mg/day in 1‐year follow‐up. When patients filled at least one 80 mg prescription, their total days of therapy over the course of a year were significantly greater than if they did not (mono: 159.3 vs. 65.6 days; combo: 237.4 vs. 172.0; P < 0.0001). Across all timepoints examined (Day 14, 30, 60, 90, 210) for mono and combo, ATX ≥ 80 versus ATX < 80 patients had greater mean doses (P < 0.0001). Combo patients had longer ATX LoT than mono patients regardless if they reached 80 mg or not (P < 0.0001), but mono patients LoT was 93.8 days longer for ATX ≥ 80 versus ATX < 80 patients compared to 65.5 days for combo patients. Of patients reaching 80 mg/day, 71.7% of mono and 62.8% of combo patients did so by Day 30. For mono ATX ≥ 80 and ATX < 80 patients, LoT was significantly (P < 0.0001) less in previously treated patients compared to naive patients.

Conclusion

Ensuring adult ADHD patients are treated with ATX at a target dose of 80 mg/day is an important clinical consideration for maximizing patient days on therapy, which can be important for treatment optimization.