Long-term effects of stimulants on neurocognitive performance of Taiwanese children with attention-deficit/hyperactivity disorder

Neuroplasticity to autophagy cross-talk in a therapeutic effect of physical exercises and irisin in ADHD

Adaptive neuroplasticity is a pivotal mechanism for healthy brain development and maintenance, as well as its restoration in disease- and age-associated decline. Management of mental disorders such as attention deficit hyperactivity disorder (ADHD) needs interventions stimulating adaptive neuroplasticity, beyond conventional psychopharmacological treatments. Physical exercises are proposed for the management of ADHD, and also depression and aging because of evoked brain neuroplasticity. Recent progress in understanding the mechanisms of muscle-brain cross-talk pinpoints the role of the myokine irisin in the mediation of pro-cognitive and antidepressant activity of physical exercises. In this review, we discuss how irisin, which is released in the periphery as well as derived from brain cells, may interact with the mechanisms of cellular autophagy to provide protein recycling and regulation of brain-derived neurotrophic factor (BDNF) signaling via glia-mediated control of BDNF maturation, and, therefore, support neuroplasticity. We propose that the neuroplasticity associated with physical exercises is mediated in part by irisin-triggered autophagy. Since the recent findings give objectives to consider autophagy-stimulating intervention as a prerequisite for successful therapy of psychiatric disorders, irisin appears as a prototypic molecule that can activate autophagy with therapeutic goals.

The effects of psychostimulants on cognitive functions in individuals with attention-deficit hyperactivity disorder: A systematic review

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is associated with a broad range of deficits in cognitive functions which has significant implications for quality of life. Psychostimulants are demonstrated to improve symptoms of inattention and hyperactivity/impulsivity, however, their impact on cognition remains incompletely characterized. Herein, the aim of this systematic review is to synthesize the extant literature reporting on the effects of psychostimulants on cognitive function in individuals with ADHD.

METHOD

A systematic search of PubMed, Scopus, and Web of Science from inception to July 2021 was conducted. Additional studies were identified through Google Scholar and a manual search of the reference lists of relevant articles. Inclusion criteria were original studies that evaluated the cognitive function of individuals with ADHD taking psychostimulants drugs. We assessed the quality of the included papers using the Newcastle-Ottawa scale (NOS).

RESULTS

A total of 10 studies involving 753 subjects with ADHD and 194 healthy controls were identified and eligible for inclusion. Nine studies evaluated the impact of methylphenidate on cognitive function and one study investigated the use of lisdexamfetamine. Results indicated that attentional deficits such as memory, vigilance, divided attention, phasic and tonic alertness, and focused attention were improved in ADHD patients treated with psychostimulants. The efficacy of psychostimulants in improving other domains of cognition remains inconclusive due to conflicting evidence or insignificant findings (ie. academic performance and executive function). Overall, results indicate that psychostimulants may improve only select domains of cognition (ie. memory and attention).

CONCLUSION

Psychostimulants are reported to improve several disparate aspects of cognition among individuals with ADHD. Further research is needed to better understand the complex relationships between cognition and behavior in ADHD, as well as the impact of medication on these distinct aspects of functioning. Further research is also needed to determine whether the pro-cognitive effect of stimulants would be transferable to other mental disorders.

Long-term medication for ADHD and development of cognitive functions in children and adolescents

OBJECTIVE

Long-term effects of ADHD medication on cognitive functions are not well known. This study investigates development of cognitive functions and ADHD symptoms on well-controlled medication for 1 year in children and adolescents.

STUDY DESIGN

This study is part of an ongoing open uncontrolled trial of long-term medication for ADHD in children and adolescents aged 6-18 years with any form of ADHD, and frequently comorbid autism spectrum disorder (ASD, 29%) or autistic traits (24%). Other comorbidities were oppositional defiant disorder, dyslexia/language disorder, borderline intellectual functioning, developmental coordination disorder. This analysis includes 87 participants (61 boys, 26 girls) who completed Wechsler tests at baseline and after 12 months. ADHD symptoms were investigator-rated on the ADHD Rating Scale-IV at the same time points.

RESULTS

The whole group of children and adolescents showed significant improvements in Wechsler Full Scale IQ (FSIQ, mean at baseline 92.6, at 12 months 97.95), and on the Index Scales Verbal Comprehension, Working Memory and Processing Speed, after one year of well-controlled ADHD medication. Comorbid dyslexia/language impairment predicted a larger rise in FSIQ, but not gender, ADHD presentation or comorbid ASD. Robust improvements in ADHD symptoms were observed (mean ADHD-Rating Scale score at baseline 34.6, and at 12 months 18.3).

CONCLUSIONS

Cognitive test scores and ADHD symptoms were improved on well-controlled medication for 1 year in children and adolescents with ADHD, autism and other comorbidities. The main study limitation is the open uncontrolled trial design.

Long-term effects of stimulant treatment on ADHD symptoms, social-emotional functioning, and cognition

BACKGROUND

Methodological and ethical constraints have hampered studies into long-term lasting outcomes of stimulant treatment in individuals with attention-deficit/hyperactivity disorder (ADHD). Lasting effects may be beneficial (i.e. improved functioning even when treatment is temporarily ceased) or detrimental (i.e. worse functioning while off medication), but both hypotheses currently lack empirical support. Here we investigate whether stimulant treatment history predicts long-term development of ADHD symptoms, social-emotional functioning or cognition, measured after medication wash-out.

METHODS

ADHD symptoms, social-emotional functioning and cognitive test performance were measured twice, 6 years apart, in two ADHD groups (stimulant-treated versus not stimulant-treated between baseline and follow-up). Groups were closely matched on baseline clinical and demographic variables (n = 148, 58% male, age = 11.1). A matched healthy control group was included for reference.

RESULTS

All but two outcome measures (emotional problems and prosocial behaviour) improved between baseline and follow-up. Improvement over time in the stimulant-treated group did not differ from improvement in the not stimulant-treated group on any outcome measure.

CONCLUSIONS

Stimulant treatment is not associated with the long-term developmental course of ADHD symptoms, social-emotional functioning, motor control, timing or verbal working memory. Adolescence is characterised by clinical improvement regardless of stimulant treatment during that time. These findings are an important source to inform the scientific and public debate.

Long-Term Efficacy of Methylphenidate Immediate-Release for the Treatment of Childhood ADHD

OBJECTIVE

To evaluate the long-term effects of methylphenidate imediate-release (MPH-IR), and to confirm the efficacy established in previous meta-analyses of short-term studies.

METHOD

Published and unpublished studies in which participants were treated with MPH-IR for 12 weeks or more were searched. Pooled effect sizes from these studies were computed with the DerSimonian and Laird random-effect model. Meta-regression analysis was conducted to estimate covariates associated with treatment effects.

RESULTS

Seven studies were included. Pooled parents ratings for inattention and hyperactivity/impulsivity resulted in standardized mean difference (SMD) = 0.96 (95% confidence interval [CI] = [0.60, 1.32]) and SMD = 1.12 (95% CI = [0.85, 1.39]), respectively; pooled teachers ratings showed SMD = 0.98 (95% CI = [0.09, 1.86]) for inattention and SMD = 1.25 (95% CI = [0.7, 1.81]) for hyperactivity/impulsivity. No evidence of association of any covariates with treatment effect was detected in the meta-regression.

CONCLUSION

MPH-IR is efficacious for childhood ADHD for periods longer than 12 weeks.

An Open-label, Self-control, Prospective Study on Cognitive Function, Academic Performance, and Tolerability of Osmotic-release Oral System Methylphenidate in Children with Attention-deficit Hyperactivity Disorder

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) is the most common mental and behavioral disorder in school-aged children. This study evaluated the effect of osmotic-release oral system (OROS) methylphenidate (MPH) on cognitive function and academic performance of Chinese school-aged children with ADHD.

METHODS

This 12-week, prospective, multicenter, open-label, self-controlled study enrolled 153 Chinese school-aged children with ADHD and 41 non-ADHD children. Children with ADHD were treated with once-daily OROS-MPH (18 mg, 36 mg, or 54 mg). The primary endpoints were Inattention/Overactivity (I/O) with Aggression Conners Behavior Rating Scale (IOWA) and Digit Span Test at week 12 compared with baseline. Secondary endpoints included opposition/defiant (O/D) subscale of IOWA, Clinical Global Impression (CGI), Coding Test, Stroop Color-word Test, Wisconsin Card Sorting Test (WCST), academic performance on teacher-rated school examinations, and safety at week 12 compared with baseline. Both non-ADHD and ADHD children received the same frequency of cognitive operational test to avoid the possible bias caused by training.

RESULTS

A total of 128 patients were evaluated with cognitive assessments. The OROS-MPH treatment significantly improved IOWA Conners I/O subscale scores at week 12 (3.8 ± 2.3) versus baseline (10.0 ± 2.4; P < 0.0001). Digit Span Test scores improved significantly (P < 0.0001) with a high remission rate (81.1%) at week 12 versus baseline. A significant (P < 0.0001) improvement was observed in O/D subscale of IOWA, CGI, Coding Test, Stroop Color-word Test, WCST, and academic performance at week 12 versus baseline. Very few practice-related improvements were noticed in the non-ADHD group at week 12 compared with baseline. No serious adverse events and deaths were reported during the study.

CONCLUSIONS

The OROS-MPH treatment effectively controlled symptoms of ADHD and significantly improved academic performance and cognitive function of Chinese school-aged children with ADHD. The treatment was found to be safe and generally well-tolerated over 12 weeks.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01933880; http://clinicaltrials.gov/ct2/show/NCT01933880?term=CONCERTAATT4099&rank=1.

Pharmacological treatment of attention-deficit/hyperactivity disorder: assessing outcomes

A substantial body of evidence has supported the efficacy and safety of pharmacological treatment available for attention deficit/hyperactivity disorder (ADHD). There is increasing agreement that the important treatment outcomes for ADHD extend beyond improvement in core symptoms and that a more generic (or global) concept of remission is the overarching goal of treatment. However, there is no consensus on the best definition of remission or on how best to conceptualize and measure broader treatment outcomes. In this article, we provide an overview of the various methods and approaches to measuring treatment outcomes for ADHD with respect to symptoms, impairment, quality of life, adverse events and safety as well as cognition. We will describe the ways that they may be used within routine clinical practice and think ahead about the kinds of studies that are required to move the field forward.

Cognition and impulsivity in adults with attention deficit hyperactivity disorder with and without cocaine and/or crack dependence

BACKGROUND

Substance use disorder (SUD) is a common comorbidity in adults with attention deficit-hyperactivity disorder (ADHD). However,there have been few studies on cognitive profiles of these patients. Impulsivity is also commonly increased in both disorders. The central aim of this study was to compare cognition and impulsivity in subjects who had ADHD and cocaine dependence (ADHD+COC group) to those with ADHD only (ADHD-noSUD group). We hypothesized that the ADHD+COC group would show more marked cognitive dysfunction and greater impulsivity than their counterparts with ADHD only.

METHODS

A total of 70 adult patients diagnosed with ADHD according to (DSM-IV-TR) criteria were enrolled; 36 with ADHD+COC and 34 with ADHD-noSUD. All study participants were evaluated with a sociodemographic questionnaire; the Mini International Neuropsychiatric Interview; the Adult ADHD Self-Report Scale; the Addiction Severity Index; the Alcohol, Smoking and Substance Involvement Screening Test; the Barratt Impulsiveness Scale; and a comprehensive neurocognitive battery.

RESULTS

Compared to individuals with ADHD-noSUD, ADHD+COC individuals had significantly lower mean IQ and higher motor impulsivity. On average, the ADHD+COC group also performed more poorly on tasks assessing verbal skills, vigilance, implicit learning during decision making, and ADHD-noSUD performed more poorly on selective attention, information processing, and visual search.

CONCLUSIONS

Our results support the integrative theory of ADHD based on the cognitive and affective neuroscience model, and suggests that ADHD-noSUD patients have impairments in cognitive regulation, while ADHD+COC patients have impairments in both cognitive and affective regulation.