SUMMARY:
Under the current consensus of the international medical community, the l ADHD appears as a heterogeneous clinical syndrome inherited, associated with catecholaminergic hypofunction in prefrontal brain regions and cortical and subcortical factors environmental issues which may determine the clinical significance of it.
is a chronic syndrome that begins in the children whose symptoms persist throughout the life cycle. It is one of the most common neurobehavioral disorders in childhood and adolescence. Affects approximately 5-10% of children worldwide and frequently, symptoms persist into adulthood. The latest edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) describes the symptoms of the disorder into two groups: inattention and impulsivity-hyperactivity. The presence or absence of these gives rise to three subtypes: predominantly inattentive, predominantly hyperactive-impulsive and combined. ADHD also shows a high comorbidity with other psychiatric disorders, including disorders mood and anxiety disorders, oppositional defiant disorder or learning disabilities, still common for people diagnosed with ADHD have at least one of them.
GENETIC STUDIES:
Family studies conducted with clinical samples of parents and children with ADHD established that the risk of developing the disorder if one parent suffers is 57%.
Studies in monozygotic twins provide a concordance of the disorder up to 90%, the more severe the more consistent. Despite the high heritability of the disorder to study the genetics of ADHD has been complicated because it is not labeled by a single pair of alleles but by a combination of genes that determine membership in one of the three subtypes and individual differences in the clinical expression of the disorder. So although the symptoms of attention deficit disorder with hyperactivity (ADHD) manifest relatively stable, lasting from childhood and persist throughout the life of the individual, allowing the diagnosis. The provider, some or other symptoms and even the degree to which they are presented depends on the different possible combinations of genes, giving rise to three subtypes (inattentive, hyperactive and combined) and individual differences among individuals in each subtype. They also found genetic links to disorders such as autistic spectrum disorders, psychosis, epilepsy, OCD, etc. In addition it is also a positively correlated with intelligence (people with ADHD often have a high CI) and left-handedness, but because a few studies, the data are not conclusive.
ENVIRONMENTAL FACTORS:
Although there have been many environmental factors (both biological and psychosocial)
related to attention deficit disorder with hyperactivity (ADHD), not biological factors (toxemia, eclampsia, poor maternal health, younger age maternal, fetal age postmadura, prolonged labor, fetal distress, low birth weight, antepartum haemorrhage, alcohol, tobacco, etc.) or psychosocial factors (severe marital discord, low social class, extended family, parental criminality, maternal mental disorder and non-family foster care of children, etc..) or any combination thereof has been shown to cause necessary and / or sufficient for the manifestation of the disorder.
These factors tend to emerge as universal predictors of adaptability and mental health, and in some cases (parental criminality, family conflict, low social class, alcohol consumption and drug abuse, domestic violence, etc.). Concordance be interpreted as due to the presence in the parents of symptoms and disorders similar to those found in their children. And alert parental presence of the disorder. Never as a cause of ADHD. BEHAVIORAL COMORVIDADES
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But the study of environmental factors and family dysfunction present in children with this condition has revealed its important role in the development of symptoms, and the emergence of comorbid behavioral disorder (oppositional defiant disorder Conduct). In fact, psychosocial factors are always more general psychopathological risk that a particular risk of suffering a certain pathology neurolobiologica.
These psychosocial factors (deprived urban areas, places of poverty, malnutrition, social exclusion, poor care pre-and postnatal, family problems, alcohol and drug consumption, violence, etc..) favor the development of psychosocial disorders and contribute to its development and perpetuation. Similarly, half disorganized or highly dysfunctional school also causes a deterioration in the conduct of any child and increased school failure.
addition, studies of families of children with ADHD have resulted in a more intrusive
parenting style, controlling and disapproving than in healthy children, that negative parenting style is normally a consequence, a response to the child's symptoms. Thus, the symptoms of the child can lead parents to confidence in their ability, resulting in their stress, social isolation, feelings of guilt and depression. The impact on the children themselves, in their emotional development and self-esteem, creating a vicious cycle of negative interactions and feelings of failure that will perpetuate the family difficulties and symptomatic manifestations of ADHD. These factors contribute to the onset of comorbid disorders associated with ADHD. The same cycle can appear in the relationship between teachers with the child in the school context, with similar consequences.
In fact, some studies referred to the continuity of what
hyperactive behavior during development and, However, the maintenance of oppositional behaviors, is related in part to the use, by parents, excessive orders and criticism by adopting a management style hypercontrol and intrusive. Normally parental style ostensibly to improve the effectiveness of psychostimulants in improving the child's symptoms.
Pathophysiology:
The pattern of cognitive deficits and behavioral abnormalities found in children with ADHD
involves executive and cognitive functions in a manner similar to that seen in adults with frontal lobe damage, suggesting a frontal cortex dysfunction and / or functionally related regions.
Most structural studies (either computed axial tomography, or nuclear magnetic resonance
) find some evidence of structural abnormalities in the brains
patients studied in the right frontal cortex and basal ganglia which supports the idea of fronto-subcortical syndrome. Most functional studies (PET, SPECT and functional MRI) are also made dysfunctions in the metabolism or cerebral blood flow in these areas in these patients. Related to dopamine. However, ADHD is not only characterized by excessive motor activity and cognitive problems. People with ADHD often suffer from other difficulties pueden estar relacionadas con el desarrollo motor –retraso en la coordinación motora–, el lenguaje –retraso en la internalización del habla–, el rendimiento escolar –repetición de cursos académicos–, la motivación –necesidad de actuar con refuerzos inmediatos– o la emoción –excesiva reactividad emocional– Estas dificultades, incluidas las relacionadas con el afecto, son consideradas actualmente por el DSM-IV como ‘características asociadas o secundarias’, ya que se relacionarían o estarían generadas por los síntomas diagnósticos del síndrome: inatención, hiperactividad e impulsividad.
Recientes estudios observaron that children with ADHD had
serious difficulties in processing emotional information not only for their general cognitive limitations, but also a primary disability in the recognition and understanding of expressions. And although the deficits in emotional regulation is not currently one of the diagnostic symptoms of ADHD, various theoretical proposals suggest that a fundamental aspect of ADHD. These emotional and motivational processes also have a strong neurobiological basis probably caused by the dysfunction of three related neural circuits: frontostriatal, frontocerebelar and frontolímbico. The first two were involved in cognitive control processes (response inhibition, working memory, temporal information processing, etc..), while the third would be involved in mood regulation processes (approach avoidance behavior to emotional events or situations).
CONCLUSIONS:
symptomatic due to the heterogeneity of ADHD is difficult to explain by only one of the theories about it and still lack information on the genetics of it and even if you know some of the key genetic markers, studies continue because the known open yet to fully explain this heterogeneity, as happens to the pathophysiology, functional studies (PET, SPECT and functional MRI) are limited due to high cost, so even not be considered as final although all multi-causal models describe ADHD as a result of a number of anomalies in the neural circuitry underlying the one hand, the cognitive control processes, and the other to the affective processes, such abnormalities are genetically inherited and environmental influence in its clinical expression would be the same as for any healthy person in the development of his personality or character.
Bibliography:
This article is based on the studies and articles in the following authors and is intended as a summary of current knowledge about what is ADHD. But the investigations are open and as in recent years much has been achieved in understanding the neurobiological syndrome can not yet say that knowledge of ADHD is complete.
- Herreros, O., Rubio B., Sánchez, F., Gracia, R. (Rev Psiquiatr ADHD Child-Juv 2002) J.
Albert, S. López-Martín, A. Fernández-Jaén b, L. Carretié (EMOTIONAL DISORDERS IN THE ATTENTION DEFICIT DISORDER / HYPERACTIVITY: EXISTING DATA AND ISSUES OPEN)
- Yolanda Martínez Ortega, Rosa Bosch Muns, Montserrat Gomà-i-Freixanet, Sergi Ventura Valero, Josep Antoni Ramos-Quiroga, Mariana Nogueira yMiguel Brugué Homes. (Variable Differential personality subtypes of ADHD in adulthood.)
- Julio Cesar Flores Lázaro (Characteristics of comorbidity in the different subtypes of attention deficit disorder with hyperactivity)
- Ant Josep Ramos Quiroga (ADHD in adults, genetic factors, diagnosis and treatment)
- Thomas E. Brown, Ph.D. (Manual of complications from attention deficit disorder with hyperactivity in children and adults).
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