Abstract
Though there is agreement on the description, incidence and main neuroanatomical findings in Attention Deficit Hyperactivity Disorder (ADHD), as well as on the fact that this syndrome affects children who have undergone either high-risk conditions during pregnancy, during delivery or at the postnatal periods, there are discrepancies in interpretation of these observations. The symptoms of ADHD undoubtedly represent the predominance of excitation over inhibition processes (delay, stimulus discrimination and differentiation, etc.), which economize and make the behavior of the organism more effective.
At the level of plasma membranes of neurons, one of the factors of inhibition is considered to be the chloride channel. It and all other active protein complexes (channels, receptors, enzymes) must have a stable spatial orientation.
Although the chloride channel has some intracellular fixation, it must also have fixation points in the space of the lipid bilayer. This can be offered by fatty acids with a longer chain and with more double bonds - especially docosahexaenoic acid.
This acid has millions of possible spatial variations and normally represents one-fifth of all fatty acids in the mammalian brain. Lack of PUFA omega 3 fatty acids in the body (and subsequently in the CNS) can pose a significant risk to the functionality of neuronal membranes (for its fluidity and the ability to anchor proteins in the membrane).
We have shown that so-called high-risk newborns, i.e. premature infants, with low birth weight, in the presence of gestational diabetes in mothers, in hypotrophy, etc., show a significant deficit of just unsaturated fatty acids of the omega 3 series. Similarly, stressful situations, e.g. nutritional deprivation also causes an acute decrease in PUFA omega 3 levels in the body (and subsequently in the CNS) can pose a significant risk to the functionality of the neuronal membrane (for its fluidity and also the ability to help anchor proteins in the membrane).
Resting membrane potential depends on the activity of the transmembranous localized enzyme Na-K ATPase. Both hypoglycemia and short-term nutritional stress or the presence of arachidonic acid in the extracellular space significantly reduce the activity of that enzyme.
In contrast, catecholamines have been shown to increase the enzyme activity in in vivo and in vitro experiments. Among the causes of the development of ADHD syndrome not only a certain genetic predisposition is expected, but also an "unfavorable" environment that interferes with intrauterine and postnatal development.
In addition to their general effect, environmental factors can lead to the impairment of neuronal cell membranes and affect and retard CNS differentiation processes.