Data was obtained from the Tarnow Center for Self-Management (TCSM) in Houston, TX, a multidisciplinary practice that treats a wide variety of diagnoses, many of which have failed multiple medication trials and this study employed a retrospective chart review. Diagnoses were made by board certified psychiatrists and psychologists according to the DSM-IV-TR criteria. The data was collected over a five-year period for those who were referred for an EEG/qEEG assessment. The EEG/qEEG archival database used at TCSM contains demographic information, diagnosis, EEG phenotypes, and the number of medications prescribed for 427 clinical cases.
In addition, for secondary analysis, a rigidly defined ADHD group was created from this sample where patients needed to have a clinician-confirmed diagnosis of ADHD and have at least 6 symptoms or more on the ADHD-RS items for IA or HI. This secondary screening resulted in a sub-sample of 49 rigidly defined ADHD patients.
This database was submitted to the Texas Southern University’s (TSU) Committee for Protection of Human Subjects (CPHS) and was approved to meet the exemption categories set forth by the federal regulation 45 CFR 46.101 (b) (2) and (4).
Questionnaires and psychopathology
Given our heterogeneous psychiatric population, standard questionnaires such as a Beck’s Depression Inventory (BDI) or ADHD rating scale (ADHD-RS) are mostly used to index complaints in a sub-group of patients only (i.e. depression and ADHD respectively). Therefore, in this study, we used a generic 300 item-screening questionnaire (CNC1020; EEG Professionals, The Netherlands) designed to assess various psychological aspects. This resulted in standardized data across various DSM disorders and enabled us to link physiology to behavior, independent of DSM diagnosis, and in line with the RDoC approach. Data on construct and predictive validity of this test can be found here (http://www.eegprofessionals.nl/cnc1020_isnr_2011.pdf) and CNC1020 was reported to have high reliability (Cronbach’s alpha = 0.982). Under analysis more details are provided on how these items were scored and a score similar to the ADHD-RS-IV and sleep items were obtained.
Electroencephalogram
The patient’s EEG was recorded using the Deymed TruScan 32 equipment (Deymed, Prague), with impedance maintained below 10 k Ohm. The patients were seated in a slightly reclining chair in a silent and low light environment. An “Electrocap” was used to collect the data according to the International 10–20 System with linked ears (Fp1, Fp2, F7, F3, Fz, F4, F8, T3, C3, Cz, C4, T4, T5, P3, Pz, P4, T6, O1, and O2). A minimum of 20 minutes total data was recorded in both eyes open (10 min) and eyes closed (10 min.) resting conditions (order of these could vary among subjects). All patients (or parent) were instructed to not take any stimulant medications or drink caffeinated drinks in the morning of the EEG.
All data were manually de-artifacted, processed and analyzed by the same team (RJS & JG) using both the Human Brain Index (HBI) and the Neuroguide databases as appropriate to the age of the client. The raw EEG and quantitative EEG (QEEG) data were analyzed and reported on a case-by-case basis during routine clinical evaluation of the 427 cases, and not part of a post-hoc analysis of the client database used in this study. Drowsiness was reported when observed; though analysis was restricted to eyes open resting and eyes closed resting, excluding drowsiness and sleep state content from these results.
EEG assessment and classification
EEGs were rated consistent with the pattern definitions from Johnstone et al. (‘High frequency beta with a spindle morphology, often with an anterior emphasis’: Johnstone et al. 2005) and the examples labeled as ‘Beta Spindles’ from Clarke and colleagues (2001b) by author JG. For this study, the focus was on cases with ratings of SEB. The electrode site with maximum power of SEB and peak frequency of SEB was determined by RJS based on visual analysis of the topographical mapping provided in the routine EEG/qEEG reports. In a previous study a high inter-rater reliability of scoring SEB was reported (Kappa: 0.97; p < .0001) where authors MA and JG independently scored the occurrence of SEB (Arns et al. 2008), hence in this study we relied on SEB visually rated by JG. Furthermore, from the quantitative EEG (QEEG) reports where data were compared to a normative EEG database (HBI and Neuroguide) it was further verified that the observed SEB was a) indeed in excess based on Z-scores, b) were present primarily in the beta band; c) verified that the sites where this SEB was observed matched the topography of the deviating Z-scores, and d) were in excess compared to age appropriate norms.
Analysis
From the 300 item CNC1020, 18 items were extracted that were identical to the ADHD-RS-IV, 9 for inattention (IA) and 9 for hyperactivity and impulsivity (HI). The original ADHD-RS-IV is rated as 0, 1, 2, and 3, therefore the mean score of the CNC1020 is divided by 8 (max. CNC score), multiplied by 3 (max. score on ADHD-RS-IV), and multiplied by 9 (# of items). This results in the sum score for IA and HI, which is comparable to other published studies using the ADHD-RS-IV. In addition, the number of IA and HI symptoms have been established by using 4 as a cut-off for the CNC1020 data to denote a symptom is present, resulting in 0–9 symptoms for IA or HI, similar to the scoring for the ADHD-RS-IV.
In addition, 3 items indexing hypersomnia (I sleep too much; I get the recommended amount of sleep but don’t feel rested; I am sluggish and have trouble getting going in the morning) and 5 items indexing insomnia were extracted (When I awaken to go to the bathroom, I have trouble falling back to sleep; I am easily awakened by dreams, and have trouble falling back to sleep; I easily awaken to any noise inside or outside my home and have trouble falling back to sleep; I move around a lot in my sleep; I have trouble falling asleep at night). For these an averaged score expressed in a percentage was calculated for hypersomnia and insomnia.
SEB was scored per EEG electrode site (defined as the site with maximum amplitude) and the center frequency of the spindles was established. Frontal SEB was defined as SEB at F3, Fz or F4 (frequency: 12.1%). Sites with frequencies of SEB less than 5% were not analyzed due to too low sample sizes for further statistical analyses.
Statistics
The relationship between IA, HI, and sleep problems, as well as age, was investigated with a one-way ANOVA with factor group (with or without SEB) within the whole population, and also more specifically within a sub-group with ADHD. Differences in gender were tested using a chi-square. Based on significant associations found between SEB and behavior, exploratory analysis was performed on a per item level.
Given the exploratory nature of this study with some repeated testing and large sample size, we have set the significance level to a conservative p ≤ .01 (two-tailed). Effect sizes (ES) are reported as Cohen’s d.