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Attention-deficit hyperactivity disorder (ADHD) is linked to increased risk for substance use disorders and nicotine dependence.
To examine the effects of stimulant treatment on subsequent risk for substance use disorder and nicotine dependence in a prospective longitudinal ADHD case–control study.
At baseline we assessed ADHD, conduct disorder and oppositional defiant disorder. Substance use disorders, nicotine dependence and stimulant treatment were assessed retrospectively after a mean follow-up of 4.4 years, at a mean age of 16.4 years.
Stimulant treatment of ADHD was linked to a reduced risk for substance use disorders compared with no stimulant treatment, even after controlling for conduct disorder and oppositional defiant disorder (hazard ratio (HR) = 1.91, 95% Cl 1.10−3.36), but not to nicotine dependence (HR = 1.12, 95% Cl 0.45−2.96). Within the stimulant-treated group, a protective effect of age at first stimulant use on substance use disorder development was found, which diminished with age, and seemed to reverse around the age of 18.
Stimulant treatment appears to lower the risk of developing substance use disorders and does not have an impact on the development of nicotine dependence in adolescents with ADHD.
Reaction time (RT) variability is one of the strongest findings to emerge in cognitive-experimental research of attention deficit hyperactivity disorder (ADHD). We set out to confirm the association between ADHD and slow and variable RTs and investigate the degree to which RT performance improves under fast event rate and incentives. Using a group familial correlation approach, we tested the hypothesis that there are shared familial effects on RT performance and ADHD.
A total of 144 ADHD combined-type probands, 125 siblings of the ADHD probands and 60 control participants, ages 6–18, performed a four-choice RT task with baseline and fast-incentive conditions.
ADHD was associated with slow and variable RTs, and with greater improvement in speed and RT variability from baseline to fast-incentive condition. RT performance showed shared familial influences with ADHD. Under the assumption that the familial effects represent genetic influences, the proportion of the phenotypic correlation due to shared familial influences was estimated as 60–70%.
The data are inconsistent with models that consider RT variability as reflecting a stable cognitive deficit in ADHD, but instead emphasize the extent to which energetic or motivational factors can have a greater effect on RT performance in ADHD. The findings support the role of RT variability as an endophenotype mediating the link between genes and ADHD.
The main aims of this study were to investigate if children with
high-functioning autism (HFA) and children with Tourette syndrome (TS) can
be differentiated in their executive functioning (EF) profile compared to
normal controls (NCs) and compared to each other and to investigate
whether children with HFA or children with TS and a comorbid group of
children with both disorders are distinct conditions in terms of EF. Four
groups of children participated in this study: HFA, TS, comorbid HFA + TS,
and a NC group. All children were in the age range of 6 to 13 years. The
groups were compared on five major domains of EF: inhibition, visual
working memory, planning, cognitive flexibility, and verbal fluency.
Children with HFA scored lower than NC children on all the EFs measured.
Children with TS and NC children showed the same EF profile. The HFA group
scored lower than the TS group for inhibition of a prepotent response and
cognitive flexibility. Children with HFA performed poorer than children
with comorbid HFA + TS on all functions, with the exception of inhibiting
an ongoing response, interference control, and verbal fluency. Children
with TS and children with comorbid HFA + TS could not be differentiated
from one another in terms of EF. This study indicates that EF deficits are
highly characteristic of children with HFA in comparison to children with
TS and NC. The results suggest that for the comparison between HFA and TS
groups, it is important to take into account comorbidity. A reevaluation
of the EF hypothesis in children with TS is suggested.We thank the children and parents without whose participation
this research would not have been possible.
Research using advanced but static mind-reading tests with high-functioning adults with a pervasive developmental disorder (PDD) provided evidence for subtle social cognitive deficits. In the present study, adults with PDD were unimpaired on such tasks, relative to individually matched normal controls. Significant differences between the two groups were, however, found on a more naturalistic empathic accuracy task developed for this study. Participants viewed two videotaped interactions that both depicted a male and female stranger having an initial conversation and were asked to infer the unexpressed thoughts and feelings of the four targets. Subjects with PDD performed significantly worse on the second video. These findings suggest that the mind-reading deficit of a subgroup of able adults with PDD may only be apparent when a sufficiently complex naturalistic assessment method is being used.
Thirty hyperactive and 30 non-hyperactive children were confronted with a delay, consisting
of a waiting situation of 15 minutes, either with or without extra stimulation provided by the
presentation of a videotape. The behaviour of the child during the waiting period was
videotaped and later coded by two naive observers. In line with theories that emphasise the
stimulation-seeking function of hyperactive behaviours, such as the optimal stimulation
account and the delay aversion theory, a group by stimulation effect was hypothesised. For
two categories of activity this was found, with ADHD children displaying more activity than
non-ADHD children in the no-stimulation but not in the stimulation condition. These data
provide support for the stimulation-seeking function of certain features of ADHD
There is growing scientific interest in the precursors to the ability of conceiving other
people's minds. The present study investigates two candidate precursors, imitation
joint attention, in young children with autism and a control group of nonautistic children with a
developmental delay. Children with autism were found to be impaired or delayed in both
abilities. Gestural and procedural imitation were significantly related to mental age and
chronological age in subjects with autism. Although the evidence for an autism-specific deficit
appears to be stronger in the domain of joint-attention behaviors than it is in the domain of
imitation, it seems premature to reject imitation as a possible precursor to the development of
mindreading skills. Systematic investigations of the imitation deficit in autism are urgently
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