ADHD Flashcards
Working memory describes
what is actively being considered at any moment
Working memory is associated with
the prefrontal cortex and the parietal lobes
Working memory is modulated by the catecholamines:
dopamine (DA) and norepinephrine (NE).
Why are adolescents so impulsive and prone to taking risks?
One possible explanation is that the frontal cortex has not yet matured
Problems with selective attention are believed to be linked to inefficient information processing in the
dorsal anterior cingulate cortex (dACC)
problems with sustained attention are linked to inefficient information processing in the
dorsolateral prefrontal cortex (DLPFC).
Hyperactivity may be modulated by the
prefrontal motor cortex
impulsivity may be modulated by the
orbitofrontal cortex (OFC).
. Sustained attention is hypothetically modulated by
a cortico-striato-thalamo-cortical (CSTC) loop
Sustained attention is involves
involves the dorsolateral prefrontal cortex (DLPFC) projecting to the striatal complex
Inefficient activation of this can lead to difficulty following through or finishing tasks, disorganization, and trouble sustaining mental effort?
DLPFC (Dorsolateral prefrontal cortex)
Inefficient activation of this can result in symptoms such as paying little attention to detail, making careless mistakes, not listening, losing things, being distracted, and forgetting things
dACC dorsal anterior cingulate cortex
Impulsivity is associated with?
a cortico-striato-thalamo-cortical (CSTC) loop that involves the orbitofrontal cortex (OFC), the striatal complex, and the thalamus.
These are examples of what ADHD symptom? talking excessively, blurting things out, not waiting one’s turn, and interrupting.
Impulsivity
Motor activity, such as hyperactivity and psychomotor agitation or retardation, can be modulated by
a cortico-striato-thalamo-cortical (CSTC) loop from the prefrontal motor cortex to the putamen (lateral striatum) to the thalamus and back to the prefrontal motor cortex
If stimulation at alpha-2A and D1 receptors is too low, all incoming signals are the same, making
it difficult for a person to focus on one single task (unguided attention).
If stimulation is too high (right side) at alpha-2a and D1, incoming signals get jumbled as additional receptors are recruited, resulting
in the misdirection of attention.
ADHD is an out-of-tune
prefrontal cortex
Alterations within the orbitofrontal cortex (OFC) are hypothesized to lead to
problems with impulsivity or hyperactivity.
Inadequate tuning of the DLPFC or the dACC can respectively lead to
sustained or selective attentive symptoms
aberrations in the dorsolateral cognitive network have been observed in children with problems of
sustained attention.
Salience-provoked phasic firing will lead to bursts of DA release, and when this happens in a controlled manner it can
reinforce learning and reward conditioning, which can provide the motivation to pursue naturally rewarding experiences
When the salience-provoked phasic firing that leads to bursts of DA release is hijacked
reward circuitry can be hijacked, and impulses are followed by the development of uncontrolled compulsions to seek drugs.
What are the two types of agents that will be hypothetically beneficial in patients with ADHD by bringing prefrontal activity back to optimal level.
Agents that can lead to (1) increased release of these two neurotransmitters, or (2) increased tonic firing of these neurons
How does pruning relate to the potential development of ADHD
Incorrect pruning that occurs around 6 or 7 may reduce the development of executive function. This is the age many kids are diagnosed with ADHD.
Parietal lesions can cause a neglect syndrome in which patients
ignore objects, people, and even parts of their body to one side of the center of gaze.
Inconsistencies in performance, responding too fast or too slow, and procrastination are behaviors that may be impaired due to
temporal processing deficits
What tends to have a smaller volume in those with ADHD?
Cerebellum volume
Most stimulants act by enhancing
neuronal excitation
At usual doses Amphetamines
increase wakefulness and alertness, reduce fatigue, elevate mood, and augment self-confidence and initiative. Euphoria, talkativeness, and increased motor activity are likely. Task performance that had been reduced by fatigue or boredom improves.
How do amphetamines affect appetite, respirations, and pain?
decrease appetite, stimulate respirations, suppress pain response
By a mechanism that is not understood, amphetamines can enhance the
analgesic effects of morphine and other opioids
Norepinephrine acts in the heart to
increase heart rate, atrioventricular conduction, and force of contraction.
. Excessive cardiac stimulation
can cause dysrhythmias. In blood vessels, NE promotes constriction. Excessive vasoconstriction can cause hypertension
Adverse effects of stimulants
weight loss, insomnia restlessness, and cardiovascular effects
Excessive amphetamine use can result in
paranoid psychosis, characterized by hallucinations and paranoid delusions. Amphetamine-induced psychosis looks very much like schizophrenia
If withdrawal of amphetamines does not immediately remove psychosis what should be suspected
latent schizophrenia
Acute Toxicity in amphetamines
Overdose produces dizziness, confusion, hallucinations, paranoid delusions, palpitations, dysrhythmias, and hypertension. Death is rare.
Fatal overdose is associated with
convulsions, coma, and cerebral hemorrhage.
In addicts abusing methamphetamines they are finding higher incidences of
Parkinson’s disease
ADHD improvement with stimulants are generally
short term
Amphetamines work by
reuptaken into the DA terminal andpackaged into vesicles, displacing DA
Methylphenidate basically freezes
the transporter in time, preventing DA reuptake and thus leading to increased synaptic availability of DA.
Unlike amphetamine, methylphenidate is
not itself taken up into the DA terminal via the transporter.
Treatment with a selective alpha-2A agonist would lead to
increased signal via direct stimulation of postsynaptic receptors, resulting in increased ability to sit still and focus.
Atomoxetine
Therapeutic effects without abuse potential
NE reuptake blocker in nucleus accumbens
Guanfacine
Prefrontal cortex, not nucleus accumbens
Highly selective for alpha-2A
Clonidine
Prefrontal cortex, not nucleus accumbens
Less alpha-2A selective than guanfacine
More sedation and hypotension
Off label for ADHD
