Review of long-acting stimulants in the treatment of attention deficit hyperactivity disorder

Treatment Outcomes With Licensed and Unlicensed Stimulant Doses for Adults With Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-Analysis

Importance

Stimulants (methylphenidate and amphetamines) are often prescribed at unlicensed doses for adults with attention-deficit/hyperactivity disorder (ADHD). Whether dose escalation beyond US Food and Drug Administration recommendations is associated with positive risk benefits is unclear.

Objective

To investigate the impact, based on averages, of stimulant doses on treatment outcomes in adults with ADHD and to determine, based on averages, whether unlicensed doses are associated with positive risk benefits compared with licensed doses.

Data Sources

Twelve databases, including published (PubMed, Cochrane Library, Embase, Web of Sciences) and unpublished (ClinicalTrials.gov) literature, up to February 22, 2023, without language restrictions.

Study Selection

Two researchers independently screened records to identify double-blinded randomized clinical trials of stimulants against placebo in adults (18 years and older) with ADHD.

Data Extraction and Synthesis

Aggregate data were extracted and synthesized in random-effects dose-response meta-analyses and network meta-analyses.

Main Outcome Measures

Change in ADHD symptoms and discontinuations due to adverse events.

Results

A total of 47 randomized clinical trials (7714 participants; mean age, 35 (SD, 11) years; 4204 male [56%]) were included. For methylphenidate, dose-response curves indicated additional reductions of symptoms with increments in doses, but the gains were progressively smaller and accompanied by continued additional risk of adverse events dropouts. Network meta-analyses showed that unlicensed doses were associated with greater reductions of symptoms compared with licensed doses (standardized mean difference [SMD], -0.23; 95% CI, -0.44 to -0.02; very low certainty of evidence), but the additional gain was small and accompanied by increased risk of adverse event dropouts (odds ratio, 2.02; 95% CI, 1.19-3.43; moderate certainty of evidence). For amphetamines, the dose-response curve approached a plateau and increments in doses did not indicate additional reductions of symptoms, but there were continued increments in the risk of adverse event dropouts. Network meta-analysis did not identify differences between unlicensed and licensed doses for reductions of symptoms (SMD, -0.08; 95% CI, -0.24 to 0.08; very low certainty of evidence).

Conclusions and Relevance

Based on group averages, unlicensed doses of stimulants may not have positive risk benefits compared with licensed doses for adults with ADHD. In general, practitioners should consider unlicensed doses cautiously. Practitioners may trial unlicensed doses if needed and tolerated but should be aware that there may not be large gains in the response to the medication with those further increments in dose. However, the findings are averages and will not generalize to every patient.

Is Food Addictive? A Review of the Science

As ultraprocessed foods (i.e., foods composed of mostly cheap industrial sources of dietary energy and nutrients plus additives) have become more abundant in our food supply, rates of obesity and diet-related disease have increased simultaneously. Food addiction has emerged as a phenotype of significant empirical interest within the past decade, conceptualized most commonly as a substance-based addiction to ultraprocessed foods. We detail (a) how approaches used to understand substance-use disorders may be applicable for operationalizing food addiction, (b) evidence for the reinforcing potential of ingredients in ultraprocessed foods that may drive compulsive consumptions, (c) the utility of conceptualizing food addiction as a substance-use disorder versus a behavioral addiction, and (d) clinical and policy implications that may follow if ultraprocessed foods exhibit an addictive potential. Broadly, the existing literature suggests biological and behavioral parallels between food addiction and substance addictions, with ultraprocessed foods high in both added fat and refined carbohydrates being most implicated in addictive-like eating. Future research priorities are also discussed, including the need for longitudinal studies and the potential negative impact of addictive ultraprocessed foods on children. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Adult Patient Preferences for Long-Acting ADHD Treatments: A Discrete Choice Experiment

BACKGROUND AND OBJECTIVE

Treatment for attention deficit hyperactivity disorder (ADHD) requires a multifaceted approach including psychosocial interventions and pharmacological treatment. This study evaluates preferences for specific attributes associated with different long-acting stimulant treatment among US adults with ADHD.

METHODS

Patients completed an online, cross-sectional survey, incorporating a discrete choice experiment to assess preferences for attributes.

RESULTS

Analyses included 200 adults with ADHD (mean age 33.0 years; 60% self-reporting moderate severity); the mean (SD) Adult ADHD Self-Report Scale-v1.1 score was 45.9 (12.4). Overall, patients valued speed of onset most and risk of rebound least. Three population groups with distinct preferences were identified: side effect-driven (n=69, 35%), quick onset-driven (n=47, 24%) and quick onset and long duration-driven (n=84, 42%).

CONCLUSION

This study shows differences in how adults with ADHD value and assess benefit-risk trade-offs when considering the desired attributes of stimulant treatments, highlighting the importance of patient-physician shared decision-making to optimize the desired benefits of individualized treatment.

Adult ADHD and comorbid disorders: clinical implications of a dimensional approach

Attention-deficit/hyperactivity disorder (ADHD) in the adult population is frequently associated with comorbid psychiatric diseases that complicate its recognition, diagnosis and management.The prevalence of ADHD in the general adult population is 2.5% and it is associated with substantial personal and individual burden. The most frequent comorbid psychopathologies include mood and anxiety disorders, substance use disorders, and personality disorders. There are strong familial links and neurobiological similarities between ADHD and the various associated psychiatric comorbidities. The overlapping symptoms between ADHD and comorbid psychopathologies represent challenges for diagnosis and treatment. Guidelines recommend that when ADHD coexists with other psychopathologies in adults, the most impairing condition should generally be treated first.Early recognition and treatment of ADHD and its comorbidities has the potential to change the trajectory of psychiatric morbidity later in life. The use of validated assessment scales and high-yield clinical questions can help identify adults with ADHD who could potentially benefit from evidence-based management strategies.

Cognitive Improvement of Attention and Inhibition in the Late Afternoon in Children With Attention-Deficit Hyperactivity Disorder (ADHD) Treated With Osmotic-Release Oral System Methylphenidate

Long-acting medications have been developed and approved for use in the treatment of attention-deficit hyperactivity disorder (ADHD). These compounds are intended to optimize and maintain symptoms control throughout the day. We tested prolonged effects of osmotic-release oral system methylphenidate on both attention and inhibition, in the late afternoon. A double-blind, randomized, placebo-controlled study was conducted in 36 boys (7-12 years) with ADHD and 40 typically developing children. The ADHD children received an individualized dose of placebo or osmotic-release oral system methylphenidate. They were tested about 8 hours after taking with 2 continuous performance tests (continuous performance test-X [CPT-X] and continuous performance test-AX [CPT-AX]) and a counting Stroop. A positive effect of osmotic-release oral system methylphenidate was present in CPT-AX with faster and less variable reaction times under osmotic-release oral system methylphenidate than under placebo, and no difference with typically developing children. In the counting Stroop, we found a decreased interference with osmotic-release oral system methylphenidate but no difference between children with ADHD under placebo and typically developing children.

A review of OROS methylphenidate (Concerta(®)) in the treatment of attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a common neurobehavioural disorder with onset during childhood. It affects a child's development, both at home and at school, and impacts on social, emotional and cognitive functioning, in both the home and the school environment. Untreated ADHD is very often associated with poor academic achievement, low occupational status, increased risk of substance abuse and delinquency. Current practice guidelines recommend a multimodal approach in the treatment of ADHD, which includes educational, behavioural and mental health interventions, and pharmacological management. Stimulant medications, including methylphenidate (MPH) and amphetamine products, are recommended as first-line pharmacotherapy in the treatment of ADHD. The choice of stimulant is influenced by several factors; the most influential factor is the duration of action. Long-acting medication provides benefits long after school and work. It also increases the likelihood of once-daily dosing, thereby eliminating the need for mid-day dosing, making the treatment more private, avoiding stigma and improving adherence to medication. MPH is the most widely used psychotropic medication in child psychiatry. It was first developed for use in children as an oral, immediate-release formulation and more recently as various extended-release formulations. These latter formulations include the 12 h preparation Concerta(®) (osmotic-release oral system [OROS] MPH), which utilizes an osmotic pump system, designed to overcome the difficulties of multiple daily dosing. Since it received approval from the US Food and Drug Administration in August 2000, OROS MPH has been quickly and widely accepted as one of the preferred treatments for ADHD because of its once-daily dosing. This paper reviews the data in support of long-acting OROS MPH in children, adolescents and adults, both in ADHD and in association with its comorbidities.

Osmotic release oral system-methylphenidate improves neural activity during low reward processing in children and adolescents with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is neurobehavioral disorder characterized by inattention, hyperactivity/impulsivity and impaired reward system function, such as delay aversion and low reward sensitivity. The pharmacological treatment for ADHD includes methylphenidate (MPH), or osmotic release oral system-MPH (OROS-MPH), which increases extrasynaptic dopamine and noradrenaline levels by blocking their reuptake. Although previous functional magnetic resonance imaging (fMRI) studies revealed that acute treatment with MPH alters activation of the nucleus accumbens during delay aversion in children and adolescents with ADHD, the effects a relatively long period of OROS-MPH treatment on delay aversion as well as reward sensitivity remain unclear. Thus, we evaluated brain activation with fMRI during a reward sensitivity paradigm that consists of high monetary reward and low monetary reward conditions before and after a 3-month treatment with OROS-MPH in 17 children and adolescents with ADHD (mean age, 13.3 ± 2.2) and 17 age- and sex-matched healthy controls (mean age, 13.0 ± 1.9). We found that before treatment there was decreased activation of the nucleus accumbens and thalamus in patients with ADHD during only the low monetary reward condition, which was improved to same level as those of the healthy controls after the treatment. The observed change in brain activity was associated with improved ADHD symptom scores, which were derived from Japanese versions of the ADHD rating scale-IV. These results suggest that treatment with OROS-MPH for a relatively long period is effective in controlling reward sensitivity in children and adolescents with ADHD.

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Attention deficit/hyperactivity disorder (ADHD) has low reward sensitivity.

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Activity in thalamus and nucleus accumbens was decreased in low monetary reward.

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Osmotic release oral system-methylphenidate (OROS-MPH) is a medication for ADHD.

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Brain activity and ADHD symptoms were improved by 3-month treatment with OROS-MPH.

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OROS-MPH treatment for long periods may change brain activity of pediatric ADHD.

Treating attention-deficit/hyperactivity disorder in adults: focus on once-daily medications

OBJECTIVE

To review the efficacy, safety, and abuse liability of approved treatments in adults with attention-deficit/hyperactivity disorder (ADHD), with a focus on once-daily medications.

DATA SOURCES

PubMed was searched for relevant studies/reviews in English from 2002 to 2011 on adult ADHD treatments.

STUDY SELECTION

Keywords used in the search were ADHD, adults, and treatment. Limits included only clinical trials, meta-analyses, randomized controlled trials, and reviews including adults (aged ≥ 19 years).

DATA EXTRACTION

Selection criteria returned 471 publications. Retrieved studies were excluded if they primarily focused on children, treatments not indicated for ADHD, or ADHD and comorbid conditions.

DATA SYNTHESIS

An epidemiologic survey revealed that 10.9% of adults identified with ADHD had received treatment during the prior 12 months. Treatments for ADHD in adults include pharmacologic and nonpharmacologic options. US Food and Drug Administration-approved long-acting stimulants and a nonstimulant with proven efficacy and safety profiles have been developed and include osmotic-release oral system methylphenidate hydrochloride (OROS-methylphenidate), extended-release dexmethylphenidate hydrochloride, mixed amphetamine salts extended release (MAS-XR), the nonstimulant atomoxetine hydrochloride, and the prodrug lisdexamfetamine dimesylate. Long-acting stimulants differ in formulation characteristics used to achieve extended release, with OROS-methylphenidate employing an osmotic-release technology, extended-release dexmethylphenidate hydrochloride and MAS-XR using pH-dependent beads, and lisdexamfetamine dimesylate using prodrug technology. These features variably affect pharmacokinetic characteristics, duration of action, and abuse liability. While all long-acting medications have varied pharmacokinetic features, mechanism of action, and duration of effect, all are generally efficacious and safety profiles are similar.

CONCLUSION

Approved long-acting treatments in adults with ADHD were effective in improving symptoms and were generally well tolerated.

Childhood health: trends and consequences over the life course

This article first documents evidence on the changing prevalence of childhood physical and mental health problems, focusing on the development of childhood health conditions in the United States. Authors Liam Delaney and James Smith present evidence on the changing prevalence of childhood chronic conditions over time using recalled data as well as contemporaneous accounts of these childhood health problems. The raw data from both sources show sharp increases in the prevalence of most childhood physical health problems (such as asthma, allergies, respiratory problems, and migraines) over time. However, inferring trends is difficult because such data are also consistent with improved detection of childhood disease, and many of the causes of childhood disease have not worsened over time. Conclusions about rapidly rising rates of childhood physical health problems over time are premature at best, especially concerning the magnitude of trends. Documenting real changes in the prevalence of specific diseases is a high-priority research topic. In contrast, the evidence is much stronger that childhood mental health problems are becoming worse. The authors next present new evidence on the effects of early childhood physical and mental problems on health and economic status in adulthood. They find that both childhood physical and mental health problems contribute significantly to poorer adult health. However, they also find that childhood mental health problems have much larger impacts than do childhood physical health problems on four critical areas of socioeconomic status as an adult: education, weeks worked per year, individual earnings, and family income. Finally, the authors examine evidence regarding the efficacy of early mental health treatment for children in terms of promoting good health later on. Existing studies suggest that a combination of cognitive behavioral therapy and medication appears to be effective in the treatment of both anxiety and depression in children. However, much more research is needed on the efficacy of these childhood interventions into adulthood. Clinical trials have been too short to evaluate the long-term impacts of various forms of treatment, and these impacts are definitively long term.

Safety of stimulant treatment in attention deficit hyperactivity disorder: part II

IMPORTANCE OF THE FIELD

Attention deficit hyperactivity disorder (ADHD) is the most common childhood psychiatric disorder and in at least 50% of cases persists into adulthood. Treatment of ADHD with stimulants is one of the oldest and most effective pharmacological treatments in psychiatry. Yet, there continues to be controversy over the safety of stimulant medications in the treatment of ADHD.

AREAS COVERED IN THIS REVIEW

This paper is a continuation of an earlier paper that reviewed the safety profile of newer stimulant agents, especially in relation to special populations. This part II reviews, through essentially an organ-system approach, the various clinical concerns that have been raised over the safety of stimulant medications. This includes neuropsychiatric, cardiovascular effects on growth and development, and a number of other less common concerns.

WHAT THE READER WILL GAIN

A thorough review of safety concerns in stimulants that emphasizes clinical information, case reports, open series or controlled trials relating to stimulant use in the treatment of ADHD.

TAKE HOME MESSAGE

While many safety concerns have been raised in the use of stimulants, the vast majority of treatment complications are either quickly reversible or easily manageable with appropriate clinical care. The negative consequences of untreated ADHD clearly outweigh the risks of the stimulant medicines when used in an appropriate and careful manner.

Efficacy of a methylphenidate transdermal system versus t.i.d. methylphenidate in a laboratory setting

OBJECTIVE

To test the efficacy and tolerability of the methylphenidate transdermal formulation (MTS) against immediate-release methylphenidate (IR MPH) and placebo in a 12-hr analog classroom setting.

METHOD

A total of nine boys ages 6 to 9 years, medicated with MPH for ADHD, complete a within-subject, double-blind study. For the purpose of the study, the boys are administered a dose of 20 cm(2) MTS, a matched dose of IR MPH 10 mg TID, and placebo. ADHD symptoms and frequency counts of classroom rule violations and the number of math problems completed are assessed hourly, during three consecutive analog classroom sessions.

RESULTS

Findings show that, across measures and throughout the day, both treatments significantly differentiated from placebo (p < .05) but not from each other. It is also observed that the MTS produced more consistent results across the day but had a delayed onset versus IR MPH. Both medications are well tolerated with only mild reductions in sleep onset.

CONCLUSION

The MTS demonstrates comparable efficacy and tolerability to TID IR MPH.

Efficacy and tolerability of lisdexamfetamine dimesylate in children with attention-deficit/hyperactivity disorder: sex and age effects and effect size across the day

BACKGROUND

Efficacy and safety profiles by sex and age (6-9 vs 10-12 years) and magnitude and duration of effect by effect size overall and across the day of lisdexamfetamine dimesylate (LDX) vs placebo were assessed.

METHODS

This study enrolled children (6-12 years) with attention-deficit/hyperactivity disorder (ADHD) in an open-label dose optimization with LDX (30-70 mg/d) followed by a randomized, double-blind, placebo-controlled, 2-way crossover phase. Post hoc analyses assessed interaction between sex or age and treatment and assessed effect sizes for Swanson, Kotkin, Agler, M-Flynn, and Pelham (SKAMP) and Permanent Product Measure of Performance (PERMP) scales and ADHD Rating Scale IV measures. No corrections for multiple testing were applied on time points and subgroup statistical comparisons.

RESULTS

129 participants enrolled; 117 randomized. Both sexes showed improvement on all assessments at postdose time points; females showed less impairment than males for SKAMP and PERMP scores in treatment and placebo groups at nearly all times. Both age groups improved on all assessments at postdose time points. Children 10-12 years had less impairment in SKAMP ratings than those 6-9 years. Treatment-by-sex interactions were observed at time points for SKAMP-D, SKAMP total, and PERMP scores; no consistent pattern across scales or time points was observed. LDX demonstrated significant improvement vs placebo, by effect size, on SKAMP-D from 1.5-13 hours postdose. The overall LS mean (SE) SKAMP-D effect size was -1.73 (0.18). In the dose-optimization phase, common (≥2%) treatment-emergent adverse events (TEAEs) in males were upper abdominal pain, headache, affect lability, initial insomnia, and insomnia; in females were nausea and decreased weight. During the crossover phase for those taking LDX, higher incidence (≥2% greater) was observed in males for upper abdominal pain and insomnia and in females for nausea and headache. Overall incidence of TEAEs in age groups was similar.

CONCLUSION

Apparent differences in impairment level between sex and age groups were noted. However, these results support the efficacy of LDX from 1.5 hours to 13 hours postdose in boys and girls with medium to large effect sizes across the day with some variability in TEAE incidence by sex.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT00500149.

Safety of stimulant treatment in attention deficit hyperactivity disorder: Part I

BACKGROUND

The safety profile of newer stimulant products is of interest. Because most studies focus on school-age children, there is also an increased interest in the treatment of other populations. Concern continues for the risk of substance abuse in the use of stimulants.

OBJECTIVE

The purpose of this paper is to review published data on the safety and tolerability of the newer forms of stimulants, treatment in special populations, and the risks of substance abuse and dependence in the treatment of attention deficit hyperactivity disorder.

METHODS

Literature obtained through Medline and Pubmed from 1995 were reviewed as well as key articles referenced in the literature.

CONCLUSIONS

The use of the newer stimulant agents shows a safety profile of frequent, but usually mild side effects. They are generally safe in special populations. The risk of developing long-term substance abuse with attention deficit hyperactivity disorder, without co-morbidities, is small and may decrease with proper treatment. More research is needed.

Efficacy and safety limitations of attention-deficit hyperactivity disorder pharmacotherapy in children and adults

There have been major advances in the treatment and understanding of attention-deficit hyperactivity disorder (ADHD) in the last decade. Among these are the availability of newer stimulant formulations, an appreciation of the combined effects of medication and behavioural therapies, and a better understanding of the neurobiology of the disorder in children (aged 6-12 years), adolescents and adults. This article focuses on the evaluation of the efficacy and safety profiles of medications used for the management of ADHD. In assessing the various medical treatments for ADHD, certain issues and analyses have become important to address. The diagnosis, characterization and quantification of ADHD symptoms are crucial to assessing treatment effectiveness. A standardized setting for measuring the severity of ADHD symptoms is the laboratory school protocol, which simulates a school environment with tightly controlled timing of measurements. This method has been adapted successfully to the adult workplace environment to help with the evaluation of adult ADHD symptoms. Statistical analyses, such as effect size and number needed to treat, may aid in the comparison and interpretation of ADHD study results. Although an objective approach to evaluating the efficacy and safety profiles of the available medications provides necessary details about the medical options, typical clinical decisions are often based on trial and error and may be individualized based on a patient's daily routine, comorbidities and risk factors. Stimulants remain the US FDA-approved medical treatment of choice for patients with ADHD and are associated with an exceptional response rate. Findings of the Multimodal Treatment of Children With ADHD study suggest that the combination of behavioural and medical therapy may benefit most patients. Nonstimulant agents, such as atomoxetine (FDA-approved), and several non-approved agents, bupropion, guanfacine and clonidine, may offer necessary alternatives to the stimulants. This is especially important for patients who have comorbidities that are contraindicated for stimulant use based on medical issues and/or risk for stimulant abuse. Typical psychiatric comorbidities in patients with ADHD include oppositional defiant disorder, conduct disorder, major depressive disorder, bipolar disorder, anxiety, substance abuse disorder, tic disorder, and Tourette's syndrome. Although relatively safe, both stimulants and atomoxetine have class-related warnings and contraindications and are associated with adverse effects that require consideration when prescribing. Polypharmacy is a common psychiatric approach to address multiple symptoms or emergent adverse effects of necessary treatments. Future research may provide an improved understanding of polypharmacy and better characterization of the factors that influence the diagnosis and successful treatment of patients with ADHD.

Dopamine-related genotypes and the dose-response effect of methylphenidate on eating in attention-deficit/hyperactivity disorder youths

OBJECTIVE

There are individual differences in the effects of methylphenidate (MPH), a dopamine (DA) transport inhibitor, on appetite in children with attention-deficit/hyperactivity disorder (ADHD). One potential moderating factor is variation in brain DA activity, which is influenced by dopamine-related genes: the DA transporter (DAT) (SLC6A3), the DA D2 receptor (DRD2), and the DA D4 receptor (DRD4) genes. The purpose of this study was to explore the relationship between dopamine-related gene polymorphisms and food consumption in ADHD children receiving varying doses of MPH.

METHODS

In a randomized, within-subject, double-blind design, 58 ADHD children (ages 6-12 years) received placebo, 0.15, 0.3, or 0.6 mg/kg of MPH three times daily over 9 weeks. Observations of percent lunch consumed as a function of dopamine-related genotypes and MPH dose were analyzed using mixed effects regression models.

RESULTS

A significant dose-response reduction in eating was observed across all genotypes (p < 0.001). There was an interaction of DAT SLC6A3 and DRD2 genotypes and dose, because 9/9 DAT children showed a stronger effect of dose when compared with the 9/10 and 10/10 children (p < 0.001) and DRD2 A2/A2 children showed a stronger effect of dose when compared with A1/A1 and A1/A2 children combined (p = 0.007). There was no significant interaction of dose by DRD4 genotype.

CONCLUSIONS

Lunch consumption decreased as a function of MPH dose. DA-related genotypes associated with greater brain DA signaling moderated the influence of drug on consumption. These results provide information relevant to predicting which children are likely to experience the greatest appetite suppression when taking MPH.

Factors associated with treatment nonadherence among US bipolar disorder patients

OBJECTIVE

Since sustained treatment-adherence is often problematic and may limit clinical outcomes among bipolar disorder (BPD) patients, we sought risk factors to guide clinical prediction of nonadherence.

METHODS

Data were from a 2005 US national sample providing questionnaire responses by 131 randomly selected prescribing psychiatrists and their adult BPD patients. We contrasted demographic and clinical factors in treatment-adherent versus nonadherent patients (strictly defined as missing > or =1 dose within 10 days) in univariate analyses followed by multivariate logistic-regression modeling.

RESULTS

Of 429 DSM-IV BPD patients (79% type-I; 62% women; 17% minorities), 34% reported missing > or = 1 dose of psychotropic medication within 10 days, 20% missed entire daily doses at least once, and only 2.5% missed all doses for 10 days. However, their prescribing psychiatrists considered only 6% as treatment-nonadherent. Factors significantly associated with nonadherence in multivariate modeling ranked: alcohol-dependence > youth > greater affective morbidity > various side effects > or = comorbid obsessive-compulsive disorder > or = recovering from mania-hypomania. Unrelated were sex, diagnostic subtype, and other comorbidities. Since most patients received > or = 2 psychotropics, potential relationships between treatment-complexity and adherence were obscured.

CONCLUSIONS

Prevalent treatment-nonadherence among American BPD patients, and striking underestimation of the problem by prescribing clinicians may encourage increasingly complex treatment-regimens of untested value, but added expense, risk of adverse effects, and uncertain impact on treatment-adherence itself.