Lecture 26: ADHD Flashcards
(36 cards)
What is the DSM-IV diagnostic criteria?
A. Six or more the following symptoms of INATTENTION have persisted for at least six months to a degree that is MALADAPTIVE and INCONSISTENT with developmental level
As well as
B. Six or more of the following symptoms of HYPERACTIVITY-IMPULSIVITY have persisted for at least six months to a degree that is maladaptive and inconsistent with developmental level
What are the types of attention deficits seen in ADHD patients?
i. often fails to give close attention to details or makes careless mistakes in schoolwork
ii. often has difficulty sustaining attention in tasks or play activity
iii. often does not seem to listen when spoken to directly
iv. Often does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace
v. often has difficulty organizing tasks and activities
vi. often avoids, dislikes or is reluctant to engage in tasks that require sustained mental effort
vii. often loses things necessary for tasks or activities (e.g. toys, school assignments, pencils)
viii. is often easily distracted by extraneous stimuli
ix. is often forgetful in daily activities
What are the types of hyperactivity deficits seen in ADHD patients?
Six or more of the following symptoms of HYPERACTIVITY-IMPULSIVITY have persisted for at least six months to a degree that is maladaptive and inconsistent with developmental level
i. often fidgets with hands or feet or squirms in seat
ii. often leaves seat in classroom or in other situations in which remaining seated is expected
iii. often runs about or climbs excessively in situations in which it is inappropriate
iv. often has difficulty playing or engaging in leisure activities quietly
v. is often “on the go” or often acts as if “driven by a motor”
vi. often talks excessively
Impulsivity
vii. often blurts out answers before questions have been completed
viii. often has difficulty awaiting turn
ix. often interrupts or intrudes on others kids
When do symptoms have to begin presenting?
Before 7 years old
Where do the symptoms have to present?
In at least two settings (e.g. at school or work or at home)
What is the prevalence of ADHD among 8-15 year olds?
8.7% from 8-15
And
4.4% from 18-44
What causes ADHD?
We still don’t know
Is a HETEROGENEOUS
Risk factors include:
-post traumatic or infectious encephalopathy
-lead poisoning
-fetal alcohol syndrome
-neglect, family adversity, situational stress
-genetic factors/neurochemical/neuroanatomical (hypothetical)
What kind of disorder is ADHD? And all psychiatric disorders in fact?
Polygenic disorder (many genes play a role in its etiology)
What is the mean heritability of ADHD?
.75 (or .8)
If you say ADHD is 80% genetic, it means that a person with ADHD has an 80% chance that his disorder is driven by genes
What potential genes lead to ADHD?
- DRD4 (dopamine D4 receptor) transforming from D4.4 to D4.7
- DAT (Dopamine transporter protein)
Fucking with dopamine leads to ADHD
Why?
DRD4
A dopamine D4 receptor
Transforms from D4.4 – D4.7
Genes implicated in ADHD
DAT (dopamine transporter protein)
A mutation that in DAT also implicated in ADHD
What are the attentional circuits?
- Posterior system
2. Anterior system
What is a key characteristic of attention?
Attention is NOT a unitary function and does not come from one circuit
Mediated by Dopamine and NE
What is the posterior system?
Orientation to stimulus
A system of attention
-orients to and engages novel stimuli
-localized to the superior PARIETAL cortex, the superior colliculus and pulvinar (thalamic nuclei)
-receives the NE innervation from the LC which inhibits the spontaneous activity of postsynaptic neurons thereby increasing signal to noise ratio of target neurons (i.e. orientation)
What is the anterior system?
“Focus” system, allows for praxis
A system of attention
-in the prefrontal cortex and the anterior cingulate and subserves the executive system
-modulated by the ascending DA (dopamine) fibers from the VTA (ventral tegmental area)
-dopamine SUPPRESSES spontaneous activity of target neurons and reduces their responsivity to new inputs (i.e. better focusing)
What does NE do in attention circuit?
Norepinephrine circuit enhances the signal-to-noise ratio of target cells by inhibiting vbasal neuronal firing (posterior)
-orientation to signal (which makes sense because this is what we learned was the function of the parietal lobe)
What does dopamine do in attention circuit?
Dopamine circuit selectively gates inputs to the anterior attention system via D1 receptor INHIBITION of excitatory NMDA inputs
Inhibits spontaneous activity so that individual can focus
What is a key description of ADHD?
ADHD = impaired executive functions
Patient profiles are very different because of heterogeneity
ADHD is a
-label for a heterogeneous group of dysfunctions related to each ofseveral nodes along the attentional/intentional network…from cerebellum up to and including prefrontal cortex
Is ADHD a disease?
No, it is a developmental difference that leads to impairment
What is a disease that can lead to symptoms mirroring ADHD?
Damage to the prefrontal cortex
-leads to disinhibition similar to ADHD
What are defining characteristics of ADHD?
Hard to tell because people have different profiles
Adults can have
-verbal learning problems
-working memory problems
Children have
-problems with response inhibition (go vs. no go)
What do we see in the neuro-imaging findings?
-no lesions
3-10% reduced regional volumes in three areas
-less cortical activity
-3 year lag in brain development but achieving typical brain volumes by age 16
-results are NOT due to takin stimulant medication
-size of this network is correlated with degree of ADHD symptoms, particularly inhibition
What regions of brain are reduced in people with ADHD?
- Orbital-prefrontal cortex (primarily right side)
- Basal Ganglia (striatum/globus pallidus)
- Cerebellum (central vermis area, more on right side)
