The present preliminary results are indicative of the contribution of serotonergic neurotransmission to attentional processes in adults with ADHD.

BackgroundThe neurotransmitter serotonin (5-HT) has been linked to the underlying neurobiology of aggressive behavior, particularly with evidence from studies in animals and humans. However, the underlying neurobiology of aggression remains unclear in the context of attention-deficit/hyperactivity disorder (ADHD), a disorder known to be associated with aggression and impulsivity. We investigated the effects of acute tryptophan depletion (ATD), and the resulting diminished central nervous serotonergic neurotransmission, on reactive aggression in healthy controls and adults with ADHD.Methodology/Principal FindingsTwenty male patients with ADHD and twenty healthy male controls were subjected to ATD with an amino acid (AA) beverage that lacked tryptophan (TRP, the physiological precursor of 5-HT) and a TRP-balanced AA beverage (BAL) in a double-blind, within-subject crossover-study over two study days. We assessed reactive aggression 3.25 hours after ATD/BAL intake using a point-subtraction aggression game (PSAG) in which participants played for points against a fictitious opponent. Point subtraction was taken as a measure for reactive aggression. Lowered rates of reactive aggression were found in the ADHD group under ATD after low provocation (LP), with controls showing the opposite effect. In patients with ADHD, trait-impulsivity was negatively correlated with the ATD effect on reactive aggression after LP. Statistical power was limited due to large standard deviations observed in the data on point subtraction, which may limit the use of this particular paradigm in adults with ADHD.Conclusions/SignificanceTogether with previous findings, the data provide preliminary evidence of an inverse association between trait-impulsivity and the ATD effect on reactive aggression after LP (as assessed by the PSAG) in patients with ADHD and that this relationship can be found in both adolescents and adults. Because of limited statistical power larger sample sizes are needed to find main effects of ATD/BAL administration on reactive aggression in adults with ADHD.

The reliance on self-reports in detecting noncredible symptom report of attention-deficit/ hyperactivity disorder in adulthood (aADHD) has been questioned due to findings showing that symptoms can easily be feigned on self-report scales. In response, Suhr and colleagues developed an infrequency index for the Conners' Adult ADHD Rating Scale (CII) and provided initial validation for its utility in detecting noncredible symptom report. The aim of this study was to evaluate the utility of the CII in detecting noncredible aADHD symptom report by using a simulation design. Data did not support the validity of the CII for the detection of noncredible aADHD symptoms, as it failed to differentiate instructed malingerers from genuine patients with sufficient accuracy. It is concluded that there is a need for infrequency scales composed of items that were specifically developed to be endorsed infrequently and embedded within valid self-report scales.Patients' self-reports, as obtained by self-report symptom rating scales and clinical interviews, form one of the primary sources of information to establish the diagnosis of attention-deficit/ hyperactivity disorder in adulthood (aADHD; American Psychiatric Association [APA], 2013; Kooij et al., 2008). However, the reliance on self-reports for establishing a valid diagnosis of aADHD has been questioned for several reasons, as (a) high base rates of ADHD symptoms are

The difficulties male adults with ADHD have in accurately processing affective prosody may result from impairments in their ability to inhibit unwanted stimuli and impulses. No clear evidence implicates 5-HT as a cause of these impairments.