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
Hypokinesia
vs.
Bradykinesia
Parkinsonism
- Hypokinesia: Decreased of movement
- Bradykinesia: Paucity/Slowness in initiating movement
Cogwheel Rigidity
Parkinsonism
- Rigidity + Tremor
- Jerky resistance to passive movement, as muscles tense and relax
- not velocity dependent
Parkinsonism
- the main motor symptoms of Parkinson’s disease
- i.e., TRAP
- Tremor: resting, asymmetric
- Rigidity: cogwheel; not velocity dependent
- Akinesia/Bradykinesia
- Postural Instability
Festinating
Parkinsonism
- Gait that consists of short, shuffling steps that change in speed (slow, then quick steps)
- are difficult to start and stop
- stride length and walking speed are reduced
Hypomimia
Parkinsonism
- Slow facial movements
- “mask-like” expressionless face
Hypophonia
Parkinsonism
- soft speech due to lack of coordination of facial muscles
Retropulsion
Parkinsonism
Involuntary backwards walking or running
Propulsion
Parkinsonism
- Tendency to fall forward
- patient looks like they are being pulled forward
Reemergent resting tremor
Parkinsonism
- when hands are raised up in front, there will be a pause in the tremor, then it will start up again
(vs. action tremor: immediate tremor when raising hands)
Non-motor Features of Parkinson’s Disease
Sensory:
- Pain: long-standing, often shoulder pain
- Olfactory disturbance: Loss of sense of smell
GI:
- Constipation: earliest symptoms
- Dribbling of saliva: loos of normal swallowing reflex function (not hypersalivation)
Sleep (very common): REM sleep behavior disorder; supposed to be atonic during REM sleep, but in Parkinson’s, the switch isn’t flipped
Autonomic dysfunction:
- Orthostatic hypotension
- Bladder dysfunction (urgency, frequency, nocturia)
Neuropsychiatric symptoms: depression (very common, but very treatable)
- Dopaminergic drug-induced disorder: impulse control disorders (hypersexuality, gambling, obsessions)
Lewy Body Dementia
- Similar to Parkinson’s disease, except with EARLY ONSET DEMENTIA
- Characterized by dementia, hallucinations and parkinsonian features
- Caused by accumulation of intranuclear Lewy Bodies (eosinophilic; made of alpha-synuclein) in the CORTEX
Alzheimer’s Disease
- Most common dementia
–Widespread neuronal loss and gliosis affecting the Cerebral cortex, brainstem, basal ganglia, resulting in Decrease in brain weight and volume, and Increase in ventricular volume (hydrocephalus ex vacuo) - Symptoms: slow-onset memory loss and progressive loss of everyday function; affects the activities of daily living
- will see loss of Ach (cholinergic) neurons in the nucleus basalis of Meynert
Morphologic Features:
- Cerebral atrophy
- Neuritic Plaques (ABeta Amyloid), particularly involving HIPPOCAMPUS (memory) and AMYGDALA (behavioral changes)
- Neurofibrillary Tangles (hyperphosphorylated Taue protein)
MILD COGNITIVE IMPAIRMENT (MCI)
- Defined: Acquired memory impairment beyond that which is expected for patient’s age
- Objective impairment of one or more cognitive domains of insufficient severity to interfere with ADLs
- Possible transitional state between normal aging and Dementia of Alzheimer Type (DAT)
- Annual conversion rate to DAT approximately 10-20% per year (compared to 1-2% in general population)
NEUROQUANT
- Goal: takes brain size and allows comparison to age adjusted normative range
- takes high resolution 3D T-1 weighted sagittal MRI scans as input.
- Returns full volume spatially corrected and anatomically labeled dataset with printable reports containing absolute and relative volumes of hippocampus, temporal horn and other gray matter structures.
- Fully automated segmentation highly consistent and reproducable and allows development of age adjusted normative range
In AD Patient, will see shrunken hippocampus; enlarged lateral ventricles
NeuroQUARC
) involves serial image analysis for accurate measuring of VOLUMETRIC CHANGE
- Compared to baseline imaging:
- Red/Yellow shows volume increase
- Blue shows volume loss
Predisposing Factors for Alzheimer’s Disease
Sporadic AD Predisposing Factors:
- Age
- ApoE4
Early Onset Predisposing Factors:
- Presenilin 1
- Down Syndrome (Trisomy 21)
- APP on Chromosome 21
ApoE2 is protective
Donepezil
- Only available treatment for AD
- Acetylcholinesterase inhibitor
- Facilitate more Acetylcholine at synaptic cleft
- Increase functional activity in remaining neurons
