Disorders of Childhood & Adolescence ADHD & Complex Illness
Speaking of Vermont adolescent Illingness...watch video
Thanks B!
On a need-to-know basis...
How common is childhood psychiatric illness?
20% of children 9 - 17 have a diagnosable psychiatric illness (~ 15 million), but very few get treatment. This can lead to a cascade of effects resulting from school drop-out, crime, etc.
Limbic disorders are not just genes or environment, but the interaction of a set of genes with a set of environmental factors. “almost all human diseases are complex-content dependent entities to which our genes make a necessary but only partial contribution.”
“What is inherited is the manner of reaction to a given environment”
Elmer Heyne, wheat geneticist, early 1900’s
How does the serotonin system function in anxiety?
Anxiety and depression are associated with environmental factors (trauma, abuse...) interacting with genetic predisposing factors (COMT, MAOA, 5HT1B, and SERT). There is a "short" and a "long" form of the SERT gene promoter. short/short are more likely to develop depression within a context of adversity or a stressful life event (SLE) and show reduced connectivity between amygdala and cingulate.
How does the dopamine system function in ADHD?
Two components of the dopamine system are the presynaptic dopamine transporter (DAT) that removes DA from the synapse, and the post-synaptic DA receptor that propagates the singal. The 10-repeat allele of the transporter DAT1 is hyperactive and the 7-repeat allele of the receptor DRD4 is hyposensitive thus in a sense reducing effective DA signaling, and both are associated with ADHD. People who have DA deficient brain will seek it out (addiction) because mesolimbic pathways to nucleus accumbens (which are dopaminergic) are hypofunctional so to get that "James Brown" feeling you feel you've got to enhance that signal. Additionally, methylphenidate (Ritalin) is a DA reuptake inhibitor that is commonly prescribed for ADHD.
Combining genomics with functional imaging studies allows identification of changes ocurring in psychiatric disorders.
For example, Catechol-O-methyl transferase (COMT) is an enzyme that breaks down catecholamines such including dopamine There are two genetic isoforms that depend on a single amino acid termed Val/Val, Val/Met, Met/Met Val has 4 times the COMT activity as the Met isoform which should then lead to lower dopamine levels in PFC in Val/Val individuals. This is thought to lead to increased activity of PFC "...neurons with valine-variant COMT show higher levels of activation during certain cognitive tasks, as they require higher levels of neuron firing to achieve the same level of post-synaptic stimulation." and a greater risk of ADHD and schizophrenia.
Coronal Sections
Try your hand at the Checkllist for Coronal Slices:
COMET has these lucites labled for reference...
corpus callosum (genu , body and splenium), cingulate gyrus
lateral ventricles (anterior, inferior, and posterior horns, body, and trigone, interventricular foramen) and septum pellucidum
caudate (head , body and tail), putamen, striatum
globus pallidus, lentiform
internal, external and extreme capsules, claustrum, insula,
internal capsule (anterior and posterior limbs), nucleus accumbens, basal forebrain area,
hypothalamus (boundaries),
amygdala, stria terminalis, hippocampus (Ammon’s horn), fornix (crus, body, columns and fimbria)
mamillothalamic tract
thalamus (anterior tubercle), massa intermedia , medial and lateral geniculates, pulvinar)
stria medullaris thalamicus, habenula, pineal gland, posterior commissure
subthalamic nucleus of the ventral thalamus
Then try your had at the limbic checklist:
Parahippocampal Gyrus
Hippocampal formation (Atlas figure 64, Hippocampus (Ammon’s Horn), Dentate Gyrus, Subiculum)
Fornix- crus, body, columns
Mamillothalamic tract
Thalamus (Anterior thalamic tubercle)
Anterior limb of the internal capsule
Cingulate gyrus & Cingulum
Prefrontal cortex (Dorsolateral prefrontal cortex, Orbitofrontal cortex)
Amygdala & Uncus & Stria terminalis
Anterior perforated substance (Basal forebrain area)
Nucleus accumbens
Stria medullaris thalamicus & Habenula
Hypothalamus (anterior commissure, hypothalamic sulcus, mamillary body, lamina terminalis)
Next up anxiety & panic disorders, anxiolytics and sedatives...
