Disorders of Executive Function: Dementias, ADHD Flashcards
Dementia of Alzheimer’s Type (DAT)
“Perceptual Integrating” Brain
- Memory, sensory association and interpretation pathways
- Location: Posterior to motor strip
- Regulation: Cholinergic (ACh)
nDAT
“Action brain” (nDAT)
- Executive functions, motor outflow: e.g., attention, planning, sequencing, working memory, initiating action
- WILL HAVE RELATIVE PRESERVATION OF MEMORY
- Location: “Prefontal cortex”
- Regulation: Dopamine (DA), norepinephrine (NE), serotonin (5HT)
Subdivision of PFC for Executive Functions
Dorsolateral Prefrontal Cortex
Subdivision of PFC for appraisal of emotional information
Orbital & Medial Prefrontal Cortex
Subdivision of PFC that Inhibits Responses
Anterior Cingulate Gyrus
Stroop Test
- Name the color, not the word
- Requires inhibition of the incorrect response (anterior cingulate)
- Mistakes related to attentional fatigue
Etiologies of nDAT
- HIV
- Head injury
- “Pseudodementia” (depressive dementia)
- Cancer chemotherapy
- Heavy metals (lead)
- Parkinson disease*
- Huntington disease*
- Normal pressure hydrocephalus
- DM, ASCVD
- Viral (CJD)
- Diagnosed post mortem: Pick’s Disease, Lewy Body Dementia
Pseudodementia
- Symptoms of dementia (loss of memory and concentration) brought on by depression
- common in elderly
Huntington Disease
- Autosomal dominant disorder characterized by expanded trinucleotide repeat (CAG) in the huntingtin gene
- Further expansion of repeats during spermatogenesis leads to ANTICIPATION in future generations
Mech: Degeneration of GABAergic neurons (inhibitory) in the caudate nucleus of the basal ganglia
Presentation: (avg age is 40 yo)
- Chorea (random firing of muscles)
- Dementia: Apathy, slowing, amnesia, anxiety,depression, psychosis, violence
- Suicide is common cause of death
CT: Loss of Caudate nucleus, resulting in “Butterfly Pattern”
Parkinson Disease
Mech: Degenerative loss of dopaminergic neurons in the substantia nigra –> cannot initiate movement
D1: increases stimulation to cortex
D2: decreases inhibition to cortex
Clinical presentation (TRAP):
- Tremor (75% are tremulous; 25% are atremulous)
- Rigidity: not velocity dependent
- Akinesia/bradykinesia
- Postural instability/shuffling gait: is primary; NOT visual, proprioceptive, vestibular, or cerebellar)
Dementia is common feature of late disease
Histology: Lewy body accumulation (intranuclear inclusion composed of alpha-synuclein)
Normal Pressure Hydrocephalus
- There is an increase in subarachnoid space volume due to expansion of the ventricles
- There is NO INCREASE in CSF pressure b/c of the expansion of the ventricles
Clinical triad:
- Urinary incontinence
- Ataxia
- Cognitive dysfunction (Dementia)
Attention Deficit Disorder
- A functional frontal syndrome: disturbance in executive functions, and failure to inhibit
- Overdiagnosed in boys; Underrecognized in girls
Subtypes:
- Impulsive
- Hyperactive
- Inattentive
Clinical:
- Learning problems, often sparing general intelligence, but may include social learning, judgment, assessment of consequences, planning
- Poor social skills
- “Difficult” temperament
- Low self esteem, depression, anxiety and misconduct
- Substance abuse when untreated
Neuroimaging: decreased brain volume; Dysfunction in networks connecting brain areas
Risk factors for ADD
- Family history (highly genetic)
- Maternal smoking/alcohol during pregnancy
- Lead
- NOT SUGAR (some possible reactions to food dyes)
- Rarely allergy, head trauma, cns insult
Attention Deficit Hyperactivity Disorder
- Age inappropriate
- Multiple settings (but not necessarily all the time/everywhere)
- Functional consequences (academic, social, family life)
- Preserved general intelligence
- May persist into adulthood
Pathogenesis of Parkinsonian Tremor
- Triggered when not enough dopamine is going to the PALLIDUM
- Tremor is ASYMMETRIC (may be unilateral or bilateral, but is ALWAYS ASYMMETRIC)
- Pill-rolling
- Resting tremor – muscles completely supported against gravity