Supplementary materials and methods.
Patients in the BD and ADHD groups were selected using the following inclusion criteria: 1) age
between 18 and 55 years; 2) diagnosed with Type-II BD or adult ADHD, respectively, according
to the DSM-IV, using the Structured Clinical Interview for DSM-IV (SCID) (First 1996); and 3)
euthymia scores less than or equal to 8 points, according to the Montgomery-Asberg Depression
Rating Scale (MADRS), (Montgomery and Asberg 1979) and less than or equal to 6 according to
the Young Mania Rating Scale (YMRS) (Young, Biggs et al. 1978) for at least 8 weeks and with
no change in medication type or dosage over 4 months. No patient received antipsychotics.
Controls (CT) were group-matched to the clinical groups for sex, age, handedness, and years of
education. Exclusion criteria were as follows: 1) other Axis-I diagnoses, except for generalized
anxiety disorder, and 2) a history of intellectual disability, neurological disease, or any clinical
condition that might affect cognitive performance. All patients with ADHD were taking
methylphenidate, which was suspended on the day of EEG recordings because this medication
affects cognitive performance (Volkow, Wang et al. 2004). CT subjects were selected from a pool
of volunteers who did not have a history of drug abuse or a family history of neurodegenerative
or psychiatric disorders. EEGs were recorded in a separate session on the same day. During the
experiment, participants and EEG recordings were monitored to assure that subjects maintained
vigilance and did not fall asleep.
Ethics
All participants provided written informed consent in agreement with the Helsinki declaration.
Although some of the participants have diagnosis of ADHD or bipolar conditions, any of those
disorders implied a reduced capacity to consent. The Ethics Committee of the Institute of
Cognitive Neurology (INECO) approved this study.
Clinical, symptomatic and neuropsychological assessment
All participants completed a series of psychiatric and behavioral questionnaires to establish a
clinical symptom profile that included depression, mania, impulsivity, anxiety, attention and
hyperactivity/impulsivity scores (see Table 1). Depression was rated using the Beck Depression
Inventory II (BDI-II; (Beck, Steer et al. 1996) and the MADRS. Mania and impulsivity were
rated using the YMRS and the Barratt Impulsiveness Scale (BIS-11) (Barratt 1985), respectively.
The symptomatic profiles of ADHD subjects were obtained from inattention and
hyperactivity/impulsivity scores on the ADHD Rating Scale for Adults (Murphy and Barkley
1996).
A neuropsychology test evaluated participants’ memory and frontal function. Memory was
evaluated using the Rey Verbal Learning Test (RAVLT) (Rey 1958 ), which examines verbal
learning, immediate and delayed recall. Frontal function was evaluated with the INECO Frontal
Screening (IFS) (Torralva, Gleichgerrcht et al. 2011), which provides a global score of executive
function as indexed by the following subtasks: motor programming, conflicting instructions, gono go, backward digits span, spatial working memory, abstraction capacity and verbal inhibitory
control. The Trail Making Test- B was used to assess attentional flexibility and attentional speed.
The Backward Digit Span, Letter-Number Sequencing and Arithmetic tests were used to assess
mental manipulation and working memory. Inhibitory control was assessed using a go-no go task
that included correct, incorrect and omitted response percentages and reaction times. A
phonological fluency task was also included.
Supplementary results
Clinical evaluation and Neuropsychological assessment
As expected, the groups differed significantly on the ADHD-RS-Inattention subscale
(F(2,31)=8.70, p=0.0012) and the ADHD-RS-Hyperactivity/impulsivity subscale (F(2, 31)=4.7,
p=0.01). Post-hoc comparisons (MS=33.32; df =27.00) showed that ADHD participants had
significantly higher scores for inattention (p=0.001) and for hyperactivity/impulsivity (p=0.01)
as compared with the CT group. Differences between groups were observed for BIS-11 scores
(F(2, 31)=5.9, p=0.007). Post-hoc comparisons (MS=375.86; df =27.00) showed that BD
subjects (p=0.005) had significantly higher scores than did CT subjects. We observed no
differences between groups for BDI-II scores (F(2, 31)=3.02, p=0.065), MADRS scores
(F(2,27)=0.57, p=0.56) or YMRS scores (F(2, 31)=2.15, p=0.13).
On memory tests, significant differences between groups (F(2,31)=5.76, p=0.007) were observed
in the recognition phase. Post-hoc comparisons (MS=1.74; df =31.00) revealed worse
performance in the ADHD group (p=0.005) as compared with the CT group.
Regarding executive function measures, no differences between groups were observed on the
total IFS score. On the go-no go task, go trial accuracy (F(2,31)=3.57, p=0.04) and omission
response percentage (F(2, 31)=3.57, p=0.04) differed significantly between groups. Post-hoc
comparisons (MS=170.05; df =27.00) revealed lower accuracy (p=0.03) and more omission
errors (p=0.003) in BD subjects as compared with control subjects (CT; p=0.03). Scores on the
verbal Phonologic Fluency Task were lower for the BD (p=0.02) and ADHD groups (p=0.02) as
compared with the CT group. Scores on the verbal Phonologic Fluency Task differed
significantly between groups (F(2, 27)=6.36, p=0.005). Post-hoc comparisons (MS=24.9; df
=27.00) showed lower performance in the BD (p=0.02) and ADHD subjects (p=0.02) as
compared with CT subjects.
Summarizing, ADHD participants had significantly worse scores for inattention, hyperactivity
and impulsivity symptoms as compared with CT subjects. The groups did not differ significantly
on BDI-II, MADRS or YMRS scores. No differences between groups were observed on
executive function or attention tasks using a frontal screening assessment. Regarding other
executive function measures, on the go-no go task, BD participants showed lower accuracy on go
trials and more omission errors as compared with CT subjects. On memory tests (recognition
phase), ADHD participants performed worse than did CT subjects. ADHD and BD participants
presented lower scores than did CT subjects on the verbal phonologic fluency task (see Table 1).
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