Executive functions

ADHD

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ADHD (Attention Deficit Hyperactivity Disorder) is one of the most prevalent (most common) psychological disorders in children and adolescents. It is a disorder that has several groups of symptoms ADHDand presentation can vary even among children. Without proper treatment, it can lead to problems in the family, at school, and in relationships with peers, and therefore it is of psychological disorders of childhood onset that receives more attention from psychiatrists and child psychologists, as well as research groups worldwide.

Therefore, here is a compendium of articles that will expand on, with the aim of raising awareness of this disorder.

  1. ADHD and DSM-V diagnostic criteria
  2. ADHD and emotional memory
  3. Cerebral cortex development in ADHD
  4. Restless Leg Syndrome and ADHD

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Specific Language Impairment (SLI) and Dyslexia

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Nowadays reading comprehension is the key to be successful in school. Children have difficulties in the early stages of learning to read and the main problem are the phonological skills. Interventions that target phonological skills need to be integrated with the teaching of reading (Hatcher, Hulme, & Ellis, 1994), and it is necessary to understand that a difference exist between dyslexia and maturational delay on reading comprehension. Some studies point out that in countries where children undergo the digital revolution, reading comprehension is worst than other countries. Preschoolers with specific language impairment (SLI) perform worst on tests of reading, spelling and reading comprehension (Snowling, Bishop, & Stothard, 2000), and children with IQ less than 100, have literacy outcomes particularly poor. We can conceptualize a subgroup in the SLI: children with specific SLI-Dyslexiareading impairment.This group shows a substantial drop in reading accuracy between the ages of 8 and 15 years. Another subgroup, over 35%, have reading skills normalized. In the opinion of Bishop, phonological difficulties place children under a literacy failure. Specific reading retardation may account for a poor vocabulary and difficulties in organizing words and syntactic difficulties. Children with problems in phonological route understand words by semantic process. They prefer to use the general meaning of the phrase to understand the word. Another problem that we find in many children with SLI are deficits in verbal working memory. A deficient working memory functioning may account for difficulties in lexical-morphological learning and sentence comprehension (Montgomery, 2003).

Children with dyslexia have a central problem in phonological loop: they have problems in the phonological representation of words and their decodification and also in cognitive processing speed. However, sometimes they have a normal reading comprehension such as dyslexics with high IQ. Dyslexics have difficulties reading pseudowords and this test is the standard for screening dyslexics.

Prevention is one of the keys to help children with SLI. A reading program with highly structured phonic component for 5 years old children is enough to master alphabetic principles and learning to read. In contrast, children at risk of reading delay need an additional training in phoneme awareness (Hatcher, Hulme, & Snowling, 2004).

In 2004 Bishop & Snowling wrote and article about differences between developmental dyslexia and specific language impairment. They explained that dyslexia was reconceptualized as a language disorder with a defficient phonological processing. The authors argued that we need to be aware of semantic and sintactic deficits in SLI. These deficits affect reading comprehension and fluency in adolescents (Bishop & Snowling, 2004).

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References

Bishop, D. V. M., & Snowling, M. J. (2004). Developmental dyslexia and specific language impairment: same or different? Psychological bulletin, 130(6), 858-886. doi:10.1037/0033-2909.130.6.858

Hatcher, P. J., Hulme, C., & Ellis, A. W. (1994). Ameliorating Early Reading Failure by Integrating the Teaching of Reading and Phonological Skills: The Phonological Linkage Hypothesis. Child Development, 65(1), 41–57. doi:10.1111/j.1467-8624.1994.tb00733.x

Hatcher, P. J., Hulme, C., & Snowling, M. J. (2004). Explicit phoneme training combined with phonic reading instruction helps young children at risk of reading failure. Journal of Child Psychology and Psychiatry, 45(2), 338–358. doi:10.1111/j.1469-7610.2004.00225.x

Montgomery, J. W. (2003). Working memory and comprehension in children with specific language impairment: what we know so far. Journal of Communication Disorders, 36(3), 221-231. doi:10.1016/S0021-9924(03)00021-2

Snowling, M., Bishop, D. V., & Stothard, S. E. (2000). Is preschool language impairment a risk factor for dyslexia in adolescence? Journal of child psychology and psychiatry, and allied disciplines, 41(5), 587-600.

Subtipos de TDAH: Inatención-Impulsividad e Hiperactividad

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El TDAH se caracteriza por presentar 3 grandes grupos se síntomas: inatención, impulsividad e hiperactividad. Cuando en un niño/a predomina la inatención, decimos que es un niño/a inatento. Los síntomas de inatención son los que más tardan en desaparecer. El niño se distrae con una mosca, se olvida la agenda en el colegio, se olvida de lavarse los dientes… El problema de la inatención tiene su base en la parte frontal del cerebro (cómo es que estos niños se despistan tanto?).

Desatención, Impulsividad, HiperactividadIntentemos entenderlo al revés. Cuando estás leyendo el diario en la cafetería y suena un móvil tu atención sin quererlo pasa de la lectura al sonido del móvil. En cuanto te das cuenta que no es tu móvil vuelves a la lectura. Si eres capaz de seguir leyendo aunque suene el móvil tienes una atención muy buena. Pierdes la atención cuando no eres capaz de inhibir tu respuesta de fijarte en otra cosa. Uno de los grandes teóricos del TDAH es Rusell A. Barkley. Fue el que teorizó que una de las grandes dificultades que tienen los niños con TDAH es inhibir sus respuestas (Barkley, 1997). Por eso se distraen con una mosca. Para entender un poco mejor qué significa inhibir la respuesta mírate el vídeo del experimento de las nubes. En este experimento clásico a un niño de 3 años se le ofrece una nube y si puede esperarse un minuto se le ofrecen dos. El vídeo no tiene desperdicio con las caras de los niños.

Los niños en los que predomina la hiperactividad, les resulta  imposible aguantar una clase entera sentados y quietos. En clase molestan a sus compañeros, se mueven en la silla y lo tocan todo. Los más pequeños suelen subirse a sitios peligrosos y tienen más accidentes que los niños de su edad. En los mayores la hiperactividad tiende a disminuir pero están más nerviosos por dentro.

La Impulsividad es la dificultad para modular o inhibir una respuesta inmediata. En clase pueden responder antes que el profesor acabe la pregunta. Tienen mala caligrafía, escriben rápido y sin fijarse. Ven las consecuencias de sus actos demasiado tarde, cuando ya han hecho algo inapropiado. Les es difícil esperar su turno en los juegos y son mal aceptados por sus compañeros.

La inatención es el síntoma más duradedo puede durar hasta la edad  adulta. La impulsividad a largo plazo puede conllevar problemas como el abuso de sustancias, cambios pareja, cambios de trabajo, etc.

Comorbilidad: el TDAH suele ir acompañado de otros trastornos, como por ejemplo, el trastorno desafiante, trastornos de aprendizaje, ansiedad, y trastornos del humor.

Ventajas: tienen mucha energía, son creativos, y bromistas.

Bibliografía

Barkley, R. A. (1997). Behavioral inhibition, sustained attention, and executive functions: Constructing a unifying theory of ADHD. Psychological Bulletin121(1), 65-94. doi:10.1037/0033-2909.121.1.65

 

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Verbal Fluency: A measure of intelligence

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Tests of verbal ability have been used by many years (Thurstone, 1938; Jones-Gotman & Milner, 1977). On this test, subject is presented with a category (e.g.words beginning with ‘M’, or names of animals) and is asked to produce as many examples of these as possible within a given time of period.

Verbal fluency has demonstrated to be impaired in dysphasic patients, but also in patients with lesions on the left (Benton, 1968) and right frontal lobe (Pendleton et al., 1982).

Naming performance has been used to test disabilities in the population. Longitudinal studies show that naming performance changes across the life span, declining specially in oldest subjects (Au et al., 1995), which reflects a breakdown in perceptual and semantic processes.

 One of the most usual tests for examining this ability is the Boston Naming Test (BNT) and the Parietal Lobe Battery. The BNT enjoys and reach database in different countries and different pathologies, as well as normative data across age range.

One important point in fluency tasks is the category of the word. When we test people with mild dementia they perform better naming animals than naming words with specified letter on the beginning, which means that category structure influences retrieval processes (Rosen, 1980).

To test naming fluency is important to control the age of the participants. An effect of aging is observed specially after forty years age and a decline of the verbal ability after the sixties (Rodriguez-Aranda & Martinussen, 2006).

Naming ability is mediated by different strategies. When we compare two measures of verbal fluency, initial letter versus excluded letter (words produced not containing a designated letter), we found that both fluency tasks rely on verbal ability and articulation speed. Excluded letter fluency performance rely more on speak and executive function (Hughes & Bryan, 2002).

Verbal fluency is also a measure of verbal intelligence. In the study of Miller (Miller, 1984), they compared verbal fluency in two groups of patients, one with focal lesions and another with dementia. They use regression to predict fluency from an index of verbal intelligence. When verbal intelligence was taking into account using regression equation, they found that impaired fluency is a specific phenomenon following frontal lesions and not a consequence of intellectual deterioration in dementia.

The most used test of verbal fluency is the FAS. It consists on a task in which the participant has one minute to generate words beginning with each letter ‘F’, ‘A’, ‘S’ (phonemic fluency) and  animal names (semantic fluency). The FAS has been shown to be more sensitive to the effects of education than age: the number of words increases as the level of education increase, while remains constant until age 60  (Tombaugh, Kozak, & Rees, 1999). Other studies have shown that level of education but not age or gender significantly influence verbal fluency (Mathuranath et al., 2003).

Neural correlates of fluency task

Letter and category fluency tasks are associated with frontal and temporal lobe. Letter fluency presents greater activation in left pre-central and inferior frontal gyrus, while category fluency presents greater activation in left middle frontal gyrus and left fusiform gyrus.

Location and cortical activity can be modulated by varying verbal fluency task demands. Right hemisphere activation is greater during automatic speech in response to over-learned category while left hemisphere activation is greater in letter fluency tasks when demands are on executive function (Birn et al., 2010). Furthermore, the uncinate fasciculus shows positive correlation with Boston Naming Test (Catani et al., 2013).

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References:

Au, R., Joung, P., Nicholas, M., Obler, L. K., Kass, R., & Albert, M. L. (1995). Naming ability across the adult life span. Aging, Neuropsychology, and Cognition, 2(4), 300-311. doi:10.1080/13825589508256605

Benton, A. L. (1968). Differential behavioral effects in frontal lobe disease. Neuropsychologia, 6, 5360.

Birn, R. M., Kenworthy, L., Case, L., Caravella, R., Jones, T. B., Bandettini, P. A., & Martin, A. (2010). Neural systems supporting lexical search guided by letter and semantic category cues: A self-paced overt response fMRI study of verbal fluency. NeuroImage, 49(1), 1099-1107. doi:10.1016/j.neuroimage.2009.07.036

Catani, M., Mesulam, M. M., Jakobsen, E., Malik, F., Martersteck, A., Wieneke, C.,… Rogalski, E. (2013). A novel frontal pathway underlies verbal fluency in primary progressive aphasia. Brain, 136(8), 2619-2628. doi:10.1093/brain/awt163

Hughes, D. L., & Bryan, J. (2002). Adult Age Differences in Strategy Use During Verbal Fluency Performance. Journal of Clinical and Experimental Neuropsychology, 24(5), 642-654. doi:10.1076/jcen.24.5.642.1002

Jones-Gotman, M. & Milner, B. (1977). Design fluency: The invention of nonsense drawings after focal cortical lesions. Neuropsychologia, 15, 653-674.

Mathuranath, P. S., George, A., Cherian, P. J., Alexander, A., Sarma, S. G., & Sarma, P. S. (2003). Effects of Age, Education and Gender on Verbal Fluency. Journal of Clinical and Experimental Neuropsychology, 25(8), 1057-1064. doi:10.1076/jcen.25.8.1057.16736

Miller, E. (1984). Verbal fluency as a function of a measure of verbal intelligence and in relation to different types of cerebral pathology. British Journal of Clinical Psychology, 23(1), 53–57. doi:10.1111/j.2044-8260.1984.tb00626.x

Pendleton, M. G., Heaton. R. K.. Lehman, R. A. W. & Hulihan, D. (1982). Diagnostic utility of  the Thurstone word fluency test in neuropsychological evaluation. Journal of Clinical Neuropsychology, 4, 307-3 17.

Rodriguez-Aranda, C., & Martinussen, M. (2006). Age-Related Differences in Performance of Phonemic Verbal Fluency Measured by Controlled Oral Word Association Task (COWAT): A Meta-Analytic Study. Developmental Neuropsychology, 30(2), 697-717. doi:10.1207/s15326942dn3002_3

Rosen, W. G. (1980). Verbal fluency in aging and dementia. Journal of Clinical Neuropsychology, 2(2), 135-146. doi:10.1080/01688638008403788

Thurstone. L. L. (1938). Primary Mental Abilities. Chicago: Chicago University Press

Tombaugh, T. N., Kozak, J., & Rees, L. (1999). Normative Data Stratified by Age and Education for Two Measures of Verbal Fluency: FAS and Animal Naming. Archives of Clinical Neuropsychology, 14(2), 167-177. doi:10.1016/S0887-6177(97)00095-4