Affective valence and arousal in ADHD and normal boys during a startle habituation experiment

Sensory Gating in Neurodevelopmental Disorders: A Scoping Review

This review aimed to explore the current understanding of sensory gating in neurodevelopmental disorders as a possible transdiagnostic mechanism. We applied methods according to the Joanna Briggs Institute Manual for Evidence Synthesis, following the population, concept, and context scoping review eligibility criteria. Using a comprehensive search strategy in five relevant research databases (Medline, EMBASE, CINAHL, PsychInfo, and Scopus), we searched for relevant peer-reviewed, primary research articles and unpublished data. Two independent reviewers screened the titles and abstracts, full-texts, and completed data extraction. We identified a total of 81 relevant articles and used descriptive analyses to summarize the characteristics and outcomes of all identified studies. Literature regarding sensory gating was most common in autistic populations with relatively fewer studies examining attention-deficit/hyperactivity disorder, tic disorders, and childhood-onset fluency disorder (COFD). The methods to assess sensory gating varied widely both within and between groups and included measures such as habituation, prepulse inhibition, affect-modulated inhibition, medication and other intervention trials. Most consistently, when participants complete questionnaires about their sensory experiences, those who have neurodevelopmental disorders report differences in their sensory gating. Affect-modulated inhibition appears to be discrepant between samples with and without neurodevelopmental disorder diagnoses. Habituation was the most commonly reported phenomenon and many differences in habituation have been found in autistic individuals and individuals with tic disorders whereas concerns with inhibition seemed more common in COFD. Overall, the evidence is inconsistent within and between disorders suggesting there is still much to learn about sensory gating in neurodevelopmental disorders.

Genetics, molecular control and clinical relevance of habituation learning

Habituation is the most fundamental form of learning. As a firewall that protects our brain from sensory overload, it is indispensable for cognitive processes. Studies in humans and animal models provide increasing evidence that habituation is affected in autism and related monogenic neurodevelopmental disorders (NDDs). An integrated application of habituation assessment in NDDs and their animal models has unexploited potential for neuroscience and medical care. With the aim to gain mechanistic insights, we systematically retrieved genes that have been demonstrated in the literature to underlie habituation. We identified 258 evolutionarily conserved genes across species, describe the biological processes they converge on, and highlight regulatory pathways and drugs that may alleviate habituation deficits. We also summarize current habituation paradigms and extract the most decisive arguments that support the crucial role of habituation for cognition in health and disease. We conclude that habituation is a conserved, quantitative, cognition- and disease-relevant process that can connect preclinical and clinical work, and hence is a powerful tool to advance research, diagnostics, and treatment of NDDs.

Habituation is altered in neuropsychiatric disorders-A comprehensive review with recommendations for experimental design and analysis

Abnormalities in the simplest form of learning, habituation, have been reported in a variety of neuropsychiatric disorders as etiologically diverse as Autism Spectrum Disorder, Fragile X syndrome, Schizophrenia, Parkinson's Disease, Huntington's Disease, Attention Deficit Hyperactivity Disorder, Tourette's Syndrome, and Migraine. Here we provide the first comprehensive review of what is known about alterations in this form of non-associative learning in each disorder. Across several disorders, abnormal habituation is predictive of symptom severity, highlighting the clinical significance of habituation and its importance to normal cognitive function. Abnormal habituation is discussed within the greater framework of learning theory and how it may relate to disease phenotype either as a cause, symptom, or therapy. Important considerations for the design and interpretation of habituation experiments are outlined with the hope that these will aid both clinicians and basic researchers investigating how this simple form of learning is altered in disease.

Methylphenidate normalizes emotional processing in adult patients with attention-deficit/hyperactivity disorder: preliminary findings

Emotional-motivational dysfunctions may significantly contribute to symptoms of attention-deficit/hyperactivity disorder (ADHD). Hyperactive-impulsive symptoms and sensation seeking could be the result of a search for reinforcers, and cognitive dysfunctions might be due to a low motivational drive. Emotional-motivational dysfunctions could also explain social dysfunctions in ADHD patients because they may lead to misinterpretations of emotional and social clues. Since methylphenidate (MPH) is the first choice as a pharmacological treatment in ADHD, we examined its influence on dysfunctional emotional processes. 13 adult ADHD patients were examined twice, without and after intake of MPH according to their personal medication regimen. The affect-modulated startle paradigm was used to assess physiological (affect-modulated startle response) and subjective (valence and arousal ratings) responses to pleasant, neutral and unpleasant visual stimuli. Healthy controls displayed affective startle modulation as expected, with startle attenuation and potentiation while watching pleasant and unpleasant pictures, respectively. In contrast, unmedicated ADHD patients displayed deficient responses to pleasant stimuli; no startle attenuation during the exposure to pleasant pictures was observed. However, MPH reinstated a normal affective startle modulation, as indicated by attenuation and potentiation associated with pleasant and unpleasant pictures, respectively. Valence and arousal ratings of patients were not affected by MPH. The data suggest that MPH as first choice treatment in ADHD has a positive impact on emotional processes in adult ADHD patients and points to the clinical relevance of emotional-dysfunctions in ADHD.

A cognitive neuroscience hypothesis of mood and depression

Although mood has a direct impact on mental and physical health, our understanding of the mechanisms underlying mood regulation is limited. Here, I propose that there is a direct reciprocal relation between the cortical activation of associations and mood regulation, whereby positive mood promotes associative processing, and associative processing promotes positive mood. This relation might stem from an evolutionary pressure for learning and predicting. Along these lines, one can think of mood as a reward mechanism that guides individuals to use their brains in the most productive manner. The proposed framework has many implications, most notably for diagnosing and treating mood disorders such as depression; for elucidating the role of inhibition in the regulation of mood; for contextualizing adult hippocampal neurogenesis; and for a general, non-invasive improvement of well-being.

Abnormal affective responsiveness in attention-deficit/hyperactivity disorder: subtype differences

BACKGROUND

Emotional-motivational dysfunctions likely contribute to attention-deficit/hyperactivity disorder (ADHD), especially to hyperactive and impulsive symptoms. This study examined the affective modulation of the startle reflex in a large sample of ADHD patients. The aim was to compare subtypes of ADHD.

METHODS

One hundred ninety-seven unmedicated adult ADHD patients (127 combined type [ADHD-C]; 50 inattentive type [ADHD-I]; 20 hyperactive-impulsive type [ADHD-HI]) and 128 healthy control subjects were examined. The affect-modulated startle response as well as valence and arousal ratings were assessed for pleasant, neutral, and unpleasant picture stimuli.

RESULTS

Control subjects exhibited startle response attenuation and potentiation by pleasant and unpleasant pictures, respectively. In ADHD-HI, startle response was not attenuated by pleasant and not potentiated by unpleasant stimuli. In ADHD-C, startle response was not attenuated by pleasant pictures, and ADHD-I responded similar to control subjects but startle response was attenuated to a lesser degree by pleasant stimuli. The ADHD-HI group rated all pictures as more positive, and male ADHD-HI rated unpleasant stimuli as less arousing.

CONCLUSIONS

This is the first study to assess the affect-modulated startle response in ADHD. It confirms emotional dysfunctions in these patients; all subtypes showed more or less diminished emotional reactions to pleasant stimuli. The hyperactive-impulsive type was also marked by blunted reactions to unpleasant stimuli. Results suggest that response patterns to emotional cues or reward may help to differentiate ADHD subtypes. Blunted emotional reactivity is especially pronounced in ADHD patients with symptoms of hyperactivity and impulsivity (ADHD-C, ADHD-HI).

Facial expression recognition in depressed subjects: the impact of intensity level and arousal dimension

The goal was to investigate whether patients with depression perform more poorly in overall emotion perception tasks compared with controls and whether this difference varies as a function of emotional intensity and arousal, with a perceptual bias toward high arousal emotions. Data were collected from 23 depressed and 23 control subjects, matched for gender, age, and education. Basic emotions were presented at 5 intensity levels ranging from 20% to 100%. Results showed that, relative to controls, patients with depression showed a significant impairment in the ability to recognize facial expressions, and that the impairment was most pronounced at subtle, but clearly recognizable emotional facial stimuli representing low arousal. Furthermore, depressed patients were found to make more misattribution errors of neutral and low arousal facial expressions in the direction of high arousal emotions. We conclude that the inability to accurately recognize nonemotional and emotional facial expressions along with the tendency for more attributions to the high arousal emotions can represent 2 basic contributing factors to the well-documented social problems of patients with depression.

Developmental changes in startle reactivity in school-age children at risk for and with actual anxiety disorder

The present study examined the development of elevated startle reactivity in anticipation of mild anxiogenic procedures in school-age children with current anxiety disorders and in those at-risk for their development due to parental anxiety. Startle blink reflexes and skin conductance responses were assessed in 7 to 12 year old anxious children (N=21), non-anxious children at-risk for anxiety by virtue of parental anxiety disorder status (N=16) and non-anxious control children of non-anxious parents (N=13). Responses were elicited by 28 auditory startle stimuli presented prior to undertaking mild anxiogenic laboratory procedures. Results showed that group differences in startle reactivity differed as a function of children's age. Relative to control children for whom age had no effect, startle reflex magnitude in anticipation of anxiogenic procedures increased across the 7 to 12 years age range in children at-risk for anxiety disorders, whereas elevations in startle reactivity were already manifest from a younger age in children with anxiety disorders. These findings may suggest an underlying vulnerability that becomes manifest with development in offspring of anxious parents as the risk for anxiety disorders increases.

The reinforcing effects of nicotine and stimulant medication in the everyday lives of adult smokers with ADHD: A preliminary examination

Whereas the smoking prevalence rates in the general population are declining, rates among people diagnosed with attention-deficit/hyperactivity disorder (ADHD) continue to be elevated. Previous research has shown that nicotine may improve attention and mood, suggesting that nicotine may help ameliorate the attentional and emotional problems associated with ADHD. The present study examined the effects of nicotine with and without stimulant medication on ADHD symptoms, moods, and arousal in the everyday lives of smokers with ADHD. A total of 10 smokers with ADHD who were being treated with stimulant medication were asked to abstain from smoking while participating in the study. Participants underwent four conditions in randomized order: (a) Nicotine patch+stimulant medication, (b) nicotine patch only, (c) placebo patch+stimulant medication, and (d) placebo patch only. Each condition continued for 2 days, during which self-reports of ADHD symptoms and moods were obtained using electronic diaries. Lightweight ambulatory monitors recorded cardiovascular activity at each diary entry. Smoking abstinence was verified by expired carbon monoxide and salivary cotinine analysis. Results showed that nicotine patches and stimulant medication alone and in combination reduced difficulty concentrating and core ADHD symptoms compared with placebo patch only. Borderline improvement in impatience and self-control was seen with nicotine patch administration primarily on day 1. Nicotine patches also tended to elevate systolic and diastolic blood pressure compared with placebo patch during day 2. The findings suggest that smokers with ADHD experience nicotine-related reductions in ADHD symptoms during their everyday lives.

Activity in children with ADHD during waiting situations in the classroom: a pilot study

BACKGROUND

According to the optimal stimulation theory and the delay aversion hypothesis, children with attention deficit hyperactivity disorder (ADHD) experience difficulties when they are confronted with low levels of stimulation and delay, respectively.

AIM

This study investigated the activity level of children with ADHD during waiting situations in the classroom. Three series of hypothesis were made: (1) with respect to the comparison between waiting and non-waiting intervals, (2) with respect to the effects of non-temporal stimulation, and (3) with respect to the effects of temporal stimulation on behaviour during waiting.

SAMPLE AND METHOD

The activity level of 14 children with ADHD and 14 control children between the ages of 6 and 11 years was observed during two non-waiting class situations and three waiting situations: without any stimulation, in the presence of nontemporal stimulation and in the presence of temporal stimulation.

RESULTS

Both groups of children obtained higher activity scores for all behavioural dimensions during waiting compared with non-waiting situations. The results further revealed additive effects of waiting and diagnostic group on behaviour. Additional nontemporal stimulation during waiting affected the behaviour of all children for most behavioural characteristics. For noisiness, additive effects were also found for diagnostic group and either non-temporal stimulation or temporal stimulation. For restlessness, a trend for an interaction effect between diagnostic group and nontemporal stimulation was found.

CONCLUSION

The findings have clear implications for school observations within an assessment protocol.

Impact of gender and age on executive functioning: do girls and boys with and without attention deficit hyperactivity disorder differ neuropsychologically in preteen and teenage years?

ADHD is known to have neuropsychological correlates, characterized mainly by executive function (EF) deficits. However, most available data are based on studies of boys through age 12. Our goal was to assess whether girls with ADHD express neuropsychological features similar to those found in boys, and whether these impairments are found in both preteen and teen samples. Participants were 101 girls and 103 boys with DSM-III-R ADHD, and 109 comparison girls and 70 boys without ADHD, ages 9 to 17 years. Information on neuropsychological performance was obtained in a standardized manner blind to clinical status. Primary regression analyses controlled for age, socioeconomic status, learning disability, and psychiatric comorbidity. Girls and boys with ADHD were significantly more impaired on some measures of EFs than healthy comparisons but did not differ significantly from each other. With the exception of 1 test score there were no significant Sex x Diagnosis interactions. Moreover, there were no more significant interactions among age, gender, and diagnosis than would be expected by chance. Neuropsychological measures of EFs were comparably impaired in girls compared to boys with ADHD, and these impairments are found at ages 9 to 12 and ages 13 to 17. These findings suggest that executive dysfunctions are correlates of ADHD regardless of gender and age, at least through the late teen years.

Adrenomedullary function during cognitive testing in attention-deficit/hyperactivity disorder

OBJECTIVE

Reported correlations between epinephrine (EPI) excretion and classroom performance, the cognition-enhancing effects of EPI infusion, increased EPI excretion with stimulants, and reports of decreased EPI excretion in attention-deficit/hyperactivity disorder (ADHD) suggest that sympathoadrenomedullary function might be altered in ADHD. This hypothesis was tested by examining sympathetic and adrenomedullary functioning during cognitive testing in boys with diagnosed ADHD.

METHOD

Urinary excretion of EPI and norepinephrine during a 3-hour cognitive test battery was assessed in 7- to 13-year-old boys. Excretion rates (nanograms per hour per square meter of body surface area) were determined in 200 individuals with ADHD (diagnosed according to DSM-IV criteria), with or without co-occurring oppositional defiant/conduct disorder or learning disorder. A non-ADHD contrast group (n = 51) with similar comorbidity was also studied.

RESULTS

Substantially lower (mean +/- SE) urinary EPI excretion was observed in the ADHD-inattentive subtype (n = 71) compared with the control group (200 +/- 22 versus 278 +/- 24 ng/hr/m2; F = 5.99, p = .015, critical alpha = .017). No diagnostic group differences were seen for norepinephrine excretion. Correlational analysis of both parent- and teacher-rated behaviors revealed that inattention factors consistently negatively predicted urinary EPI excretion.

CONCLUSIONS

The data extend findings of lower adrenomedullary activity during cognitive challenge in individuals with ADHD and suggest that the alteration is associated with inattentive behavior.