Introduction
Attention Deficit Hyperactivity Disorder (ADHD) is one of the most commonly diagnosed psychiatric conditions in childhood (Kutcher et al., 2004). Prevalence of ADHD in the general population has recently been estimated at around 5% in childhood (Faraone, Biederman, & Mick, 2006) and it is now accepted that symptoms persist leading to clinically significant impairments in adulthood, with adult prevalence estimated at 1% (Asherson, Kuntsi, & Taylor, 2005). ADHD is defined by symptoms of inattention, impulsivity, and hyperactivity (American Psychiatric Association (APA), 2000), and symptomatic individuals can have difficulties with sustained attention, lack of impulse control or inhibition, over-activity, and following instructions (Barkley, 1998).
ADHD has further been documented as a common comorbidity among individuals with intellectual disability (Buckley et al., 2006). Intellectual measures which have been shown to discriminate ADHD in adults from normal controls include subtests of the Wechsler Scales: Digit-Symbol Coding, Arithmetic, Block Design, Digit Span (Hervey et al., 2004, Quinlan, 2001). These are all subtests that rely on speed of processing and/or working memory and which may be affected by the impulsivity and attention deficits characteristic of ADHD. Additionally, increased variability in reaction time has been a consistently reported deficit in children with ADHD (Castellanos and Tannock, 2002, Russell et al., 2006).
In the present study, Raven’s Standard Progressive Matrices (RSPM) (Raven, Raven, & Court, 1998) was used. This is a measure of both visuoperception and abstract reasoning, it is easy to administer, is reasonably culturally fair, and is a reliable and valid test of non-verbal intelligence (Lezak, 1995). It is a good measure of fluid (analytical) reasoning that allows people to solve novel problems and it taps into several working memory systems (Prabhakaran, Smith, Desmond, Glover, & Gabrieli, 1997). This test was therefore considered appropriate for the purpose of the present study, although there are available other suitable timed non-verbal tests, including some of the performance subtests of the Wechsler Adult Intelligence Scale (WAIS-R, WAIS-III and WAIS-IV).
Carpenter, Just, and Shell (1990) used computer modelling to analyse the processing involved by college students completing RSPM, and found that the “ability to induce abstract relations and the ability to dynamically manage a large set of problem-solving goals in working memory” (p. 404) are key processes that distinguish between individuals completing the matrices. These are likely to be some of the areas in which individuals with ADHD have deficits (Barkley, 1997), thus individuals with ADHD may be disadvantaged on tests that require these skills and scores obtained may not always reflect true deficits. This was evident, for example, in the case of Billy Joe Friend (Gudjonsson & Young, 2006). Prior to trial Billy Joe was reported to have an IQ score of 63, consistent with learning disability, however later testing at appeal indicated a borderline full-scale IQ of 79 and additional testing showed “significant residual problems diagnostic of ADHD in childhood” (p. 213). A neuropsychological expert concluded that Billy Joe’s intellectual deficits were secondary to his ADHD and, at time of the original IQ assessment, ADHD symptoms had prevented him from completing the test at his true intellectual capacity.
There seems to be no conclusive relationship between ADHD and intelligence at present, and research appears to be particularly lacking in forensic populations. Core ADHD symptoms of impulsivity, attention, and behavioural inhibition have been reported to affect performance-based tests in which these behavioural facets are challenged (e.g. Epstein et al., 2003) and an association between speed and accuracy in test situations has also been documented, for example on the Matching Familiar Figures Task ADHD individuals tend to respond quickly but incorrectly (Young & Gudjonsson, 2005). This suggests that ADHD adults may respond to test items impulsively, possibly without giving each one full consideration, thus performing tasks quickly but inaccurately. An important research question is therefore whether current ADHD symptoms are associated with impaired intellectual performance above that of the speed of performance? If this is the case then it suggests that ADHD symptoms adversely affect the efficacy of performance (i.e. abstract problem solving).
The aim of the present study was to examine the relationship between ADHD symptoms and performance on a non-verbal test of intelligence, namely the RSPM (Raven et al., 1998), in a forensic population. Associations of childhood and adulthood ADHD symptoms with completion time and total score on the RSPM were investigated, as well as the effect that adult symptoms have on test performance. It was expected that: (1) longer RSPM test completion times would be negatively correlated with adult ADHD symptoms (H1); (2) total RSPM score would be negatively correlated with adult ADHD symptoms (H2); and (3) longer test-completion times would be positively correlated with high test scores (H3). An exploratory analysis was also conducted in order to investigate whether, when controlling for test completion time, ADHD symptoms were significantly related to the total RSPM score obtained, demonstrating special variance beyond task completion speed.
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Neural mechanism of facial expression perception in intellectually gifted adolescents
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The current study investigated the relationship between general intelligence and the three stages of facial expression processing. Two groups of adolescents with different levels of general intelligence were required to identify three types of facial expressions (happy, sad, and neutral faces), which were presented with either inverted or upright orientation. Participants’ response times and accuracy were measured and event-related potentials (ERPs) were recorded to evaluate neural dynamic processes. The behavioral results showed that high IQ adolescents exhibited shorter response times than average IQ adolescents during the facial expression identification task. The electrophysiological responses showed that no significant IQ-related differences were found for P1 responses during the early visual processing stage. During the middle processing stage, high IQ adolescents had faster structural encoding of inverted faces (shorter N170 latencies) compared to their average IQ peers, and they also showed better structural encoding of sad faces, with larger vertex positive potential (VPP) amplitudes than for neutral faces. During the late processing stage, adolescents with high IQ showed better attentional modulation, with larger late positive potential (LPP) amplitudes compared to adolescents with average IQ. The current study revealed that adolescents with different intellectual levels used different neural dynamic processes during these three stages in the processing of facial expressions.
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Efficacy of chess training for the treatment of ADHD: A prospective, open label study
Revista de Psiquiatría y Salud Mental (English Edition), Volume 9, Issue 1, 2016, pp. 13-21
To examine the effectiveness of playing chess as a treatment option for children with ADHD.
Parents of 44 children ages 6–17 with a primary diagnosis of ADHD consented to take part in the study. Parents completed the Spanish version of the Swanson, Nolan and Pelham Scale for parents (SNAP-IV) and the Abbreviated Conner's Rating Scales for parents (CPRS-HI) prior to an 11-week chess-training program. We used a paired t-test to compare pre- and post-intervention outcomes, and Cohen-d calculations to measure the magnitude of the effect. The statistical significance was set at p<.05.
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The results of our pilot study should be interpreted with caution. This pilot project highlights the importance of carrying out larger studies with a case–control design. If our results are replicated in better designed studies, playing chess could be included within the multimodal treatment of ADHD.
Examinar la efectividad del juego de ajedrez como opción de tratamiento en niños con TDAH.
Los padres de 44 niños en edades comprendidas entre 6 y 17 años, con diagnóstico primario de TDAH, dieron su consentimiento para participar en el estudio. Los padres completaron la versión española de la Escala de Swanson, Nolan y Pelham para padres (SNAP-IV) y las Escalas Abreviadas de Puntuación de Conner (CPRS-HI), con anterioridad a un programa de entrenamiento ajedrecista de 11 semanas de duración. Utilizamos la t de student pareada para comparar los resultados previos y posteriores a la intervención, así como la d de Cohen para medir la magnitud del efecto. La significación estadística se estableció en p<0,05.
Los niños con TDAH reflejaron una mejoría tanto en la escala SNAP-IV (t=6,23; grados de libertad (gl)=41; p<0,001) como en la CPRS-HI (t=5,39; gl=33; p<0,001). Nuestros resultados evidencian un elevado tamaño efecto en la disminución de la severidad del TDAH, según las mediciones de SNAP-IV (d=0,85) y CPRS-HI (d=0,85). Además, hallamos una correlación entre el cociente de inteligencia y la mejoría de la escala SNAP-IV (p<0,05).
Los resultados de nuestro estudio piloto deberán interpretarse con cautela. Este proyecto piloto subraya la importancia de realizar estudios más amplios con un diseño de control de casos. De replicarse nuestros resultados en unos estudios mejor diseñados, el juego del ajedrez podría incluirse en el tratamiento multimodal del TDAH.
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Modern Pathology, Volume 26, Issue 7, 2013, pp. 975-983
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Executive function is affected in autism spectrum disorder, but does not correlate with intelligence
Revista de Psiquiatría y Salud Mental (English Edition), Volume 9, Issue 1, 2016, pp. 39-50
Studies of executive function in autism spectrum disorder without intellectual disability (ASD-WID) patients are contradictory. We assessed a wide range of executive functioning cognitive domains in a sample of children and adolescents with ASD-WID and compared them with age-, sex-, and intelligence quotient (IQ)-matched healthy controls.
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Los estudios reflejan datos contradictorios sobre un posible deterioro en el funcionamiento ejecutivo en niños y adolescentes con trastorno del espectro autista sin discapacidad intelectual (TEA-SDI). El objetivo del estudio es evaluar el perfil cognitivo de funcionamiento ejecutivo en niños y adolescentes con TEA-SDI y compararlo con el de controles sanos pareados en sexo, edad, estatus socioeconómico, nivel educacional y cociente intelectual (CI).
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Se encontraron diferencias estadísticamente significativas en todos los dominios cognitivos evaluados a favor de un mejor rendimiento por parte del grupo control: atención (U=185,0; p=0,0005; D=0,90), memoria de trabajo (T51,48=2,597; p=0,006; D=0,72), flexibilidad cognitiva (U=236,0; p=0,007; D=0,67), control inhibitorio (U=210,0; p=0,002; D=0,71) y solución de problemas (U=261,0; p=0,021; D=0,62). Estas diferencias se mantuvieron cuando se realizaron los análisis controlando por CI.
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The relationship between intelligence and global adaptive functioning in young people with or without neurodevelopmental disorders
Psychiatry Research, Volume 303, 2021, Article 114076
Previous studies have shown an association between IQ and adaptive global functioning, i.e. how well a person is functioning in different domains of life. However, it is unclear to what extent such an association applies in children with neurodevelopmental disorders (NDDs). The study group consisted of 550 population-screened children assessed with the K-SADS, WISC-IV, and the C-GAS. Approximately half of the sample had been diagnosed with one or several NDDs (ADHD, autism, language disorder and tic disorder). A factorial ANOVA with IQ level and the presence of NDD was conducted, with C-GAS score as the dependent variable. Results revealed a significant interaction effect between IQ-group and NDD-status. In the non-NDD group (49% girls), higher IQ scores were clearly linked with better global adaptive functioning. Among children with NDDs (35% girls), however, higher IQ scores were not clearly associated with better functioning. Thus, the association between IQ and adaptive functioning were found to differ depending on the presence of NDD. These results have implications for the interpretation of IQ test results in neurodevelopmental assessments and point towards the importance of providing support based on an assessment of needs and functioning rather than scores from IQ tests.
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