Behavioral Neurology Flashcards
Types of Intelligence
Used to define age-related neurocognitive changes:
-
Crystalized intelligence
- Refers to skills, ability and knowledge that is overlearned, well-practiced
- Examples – vocabulary, general knowledge
-
Fluid intelligence
- The innate ability to process and deal with new information
- Examples – executive function, memory, processing speed
Age-Related
Neurocognitive Changes
Processing speed starts declining early
Other areas begin to decline ~ age 55
-
Stable Cognitive Areas
- Autobiographical memory
- Recall of well-learned information
- Semantic knowledge (knowledge of meanings)
- Emotional processing
-
Areas of Improvement
- Vocabulary
-
Areas of Decline
- Encoding of new memories
- Working memory
- Processing speed
Age-Related
Brain Changes
-
Decrease in gray matter volume
- Primarily dependent on diminishing connections among neurons
- Partially due to death of neurons
- Some volume decline starts after age 20
-
Decrease in white matter volume
- Primarily due to decline in number of axons
Cognition Evaluation
Neuropsychological Testing
Objective cognition evaluation
- Compare vs normative values based on education level and age
- Evaluates attention, executive function, memory, neurovisual function, language and other aspects of cognition
- Will determine whether persons cognition is aging normally or abnormally
Cognitive Impairment
Classification
- Impaired cognition established
- Then classify if:
- Minor neurocognitive disorder (mild cognitive impairment)
- Major neurocognitive disorder (dementia)
Mild Cognitive Impairment (MCI)
vs
Dementia
Main determinant of dementia vs MCI is whether cognitive deficit(s) interfere with persons abilities to perform their usual activities of daily living and work.
No affect on ADLs ⇒ mild cognitive impairment
Impairment affects ADLs ⇒ dementia
Mild Cognitive Impairment
-
MCI could be a:
-
Transitional state between normal and dementia
- If caused by progressive neurodegenerative condition
- Temporary condition caused by reversible causes
-
Static condition
- e.g. in case of cerebrovascular diseases
-
Transitional state between normal and dementia
- ~ 10% of people with MCI reverse to normal
- ~ 10% - stay stable and do not progress
- ↑ Risk for developing dementia, especially AD
- 10-15% progress to AD annually
- 80% converted to AD over 6 yr period
Major Neurocognitive Impairment (Dementia)
Differential Diagnosis
- MCI
- Depression
- Delirium
- Reversible causes of cognitive impairment
- Ex. nutritional deficiencies or metabolic abnl
- Medications
Depression Mimicking Dementia
Depression frequently has associated cognitive complaints.
Suspect that mood disorder may be the cause of cognitive complains when:
- The pt gives a lot of “I don’t know” answers
- Mismatch between test results and perception
- Pt notes more problems than are perceived by family or friends
- Hx of depression
- Other symptoms of depression are present: impaired sleep, changes in appetite etc
Distinguishing Delirium
- Usually acute-onset
- Impaired attention and alertness – reduced or hypervigilant
- Abnormal sleep pattern
- Attention, alertness fluctuations
- Profound disorientation
- There are metabolic triggers
Cognitive Impairment
Reversible Causes
- Nutrition: vitamin B12, folate deficiency
- Metabolic: TSH, other endocrine abnormalities
-
Trauma, tumor, other CNS disease
- SDH, hydrocephalus
- Infection – syphilis, meningitis, HIV, systemic
- Anemia
- Vasculitis
-
Medications
- Cardiac medications
- Antidepressants & other psychiatric meds
- Anti-epileptic drugs (AEDs)
- Sleep medications
- Bladder medications
Dementia (Major Neurocognitive Impairment)
Overview
- Acquired condition
- Involving more than one cognitive domain
- Severe enough to cause a decline in functioning
- Alzheimer’s disease is the most common type
Dementia Etiologies
- Vascular Cognitive Impairment
- Alzheimer’s Disease
- Dementia with Lewy Bodies
- Frontotemporal dementia (FTD)
- Normal Pressure Hydrocephalus
Vascular Cognitive Impairment (VCI)
Characteristics
- Abrupt-onset
-
Stepwise decline
- Patchy memory loss is usual
- VCI may know day, but not year
- More focal cognitive loses, for example naming
- May improve slightly between episodes
- Slow mental response
- Focal neurological symptoms and signs could be present
- Strokes are seen on imaging studies
- Hachinski scale: 20-point scale
- Score > 7 – vascular
- Score < 4 – degenerative
Alzheimer’s Disease (AD)
Overview
- The most common cause of dementia – about 60% of all the cases
- Insidious onset, slowly progressive
- The first sx in typical cases is usually memory loss
- Behavior problems and neuropsychiatric symptoms are common
Alzheimer’s Disease (AD)
Pathology
- A toxic peptide, beta-amyloid accumulates extracellularly
- Formed from alternate processing of the amyloid precursor protein
- Cognitive deficits do not correlate with plaque burden
-
Oligomer is the most likely culprit
- Attacks on the synapse
- Disrupts communication between neurons
- Intraneuronal hyper-P-tau accumulation
- Associated with neuronal death and development of atrophy and clinical symptoms
Alzheimer’s Disease (AD)
Symptoms
-
Cognitive symptoms
- Memory impairment; in almost all cases disease affects memory
- Orientation
- Visuospatial function
- Language
- Frontal networks
-
Neuropsychiatric
- Behavioral symptoms – aggression, agitation, restlessness, wandering, delusions, hallucinations, etc
The above affect ADLs
Alzheimer’s Disease (AD)
Atypical Signs/Symptoms
- Something other than memory issues as first symptom
- Presence of movement problems, seizures, or tremor early in disease
- Anyone under 35
- Suspected history of stroke
- History of cancer
- HIV risk factors
- Head injury
- Headache or focal symptoms
Alzheimer’s Disease (AD)
Genetics
-
Sporadic – not associated with specific mutation, might carry gene variants which increase the risk of developing the disease
- amyloid is not being cleared well in cases of sporadic disease
-
Genetic – carries specific AD mutations with 100% penetration
- amyloid is overproduced in these cases
Genes associated with AD
-
Autosomal dominant / early onset
- Chromosome 1 – Presenilin 2
- Chromosome 14 – Presenilin 1
- Chromosome 21 – APP
-
Susceptibility genes
- APOE 4 genotype (chromosome 19)
- Chromosome 12, and other
APOE Gene
- APOE E4 allele is a genetic risk factor for developing AD
- There are 3 human alleles – E2, E3 and E4
- APOE E3 allele is the most common form
-
E4 allele (10%) increases the risk of developing AD
- Shifts age of onset from ~75 to late 60’s or early 70’s
- E2 allele (10%) is protective
Alzheimer’s Disease (AD)
Diagnosis
- Clinical assessment
- Neuropsychological testing
- Biomarker studies
- Structural imaging – looking for neurodegeneration
- Functional imaging – looking for functional changes related to neurodegeneration
- Identifying amyloid
Alzheimer’s Disease (AD)
Biomarker Studies
-
Studies evaluating amyloid accumulation
- Amyloid PET scan
- CSF A-beta level measurements
-
Studies evaluating neurodegeneration
- Structural evaluation – MRI, CT
- Functional evaluation (areas of synaptic dysfunction / loss) – FDG-PET
Alzheimer’s Disease (AD)
Treatment
- Cholinergic medications: donepezil, rivastigmine, galantamine
- NMDA modulators: memantine
-
Disease modifying treatments
- ↓ Beta-amyloid
- Preventing accumulation or removing amyloid from the brain
- Immunotherapy is in development for humans
Dementia with Lewy Bodies
- Cognitive impairment with poor attention and relative sparing of memory
- Fluctuation of cognition
- Parkinsonism
- Psychotic symptoms, especially visual hallucinations
- REM sleep behavior disorder
- Autonomic instability
Frontotemporal Dementia (FTD)
Overview
- Variants: behavioral and language variants (Primary progressive aphasia)
-
Behavioral variant FTD initially presents with:
- Changes in personality
- Loss of social decorum
- Impulsivity
- Inappropriate behaviors
- Withdrawal
- Bizarre behaviors
- Primarily dysexecutive cognitive syndrome
-
Language variants (Progressive aphasias) initially presents with:
- Language function disintegration
Frontotemporal Dementia (FTD)
Anatomy of Impairment
Left frontal: expressive language, depression, frustration
Orbitofrontal: disinhibition
DLPF: executive function
Cingulate gyrus: apathy
Right temporal: bizarre, schizophrenic, facial recognition
Right frontal: irritable, disinhibition, euphoric
Left temporal: semantic impairment
Frontotemporal Dementia (FTD)
Genetics
- Tau gene – chromosome 17
- Progranulin gene – chromosome 17, TDP-43
- C9orf72 – chromosome 9
- Many unlinked mutations
Normal Pressure Hydrocephalus
- Classical clinical triad:
- Dementia
- Urinary incontinence
- Magnetic (apraxic gait)
- It can be treatable, and sometimes fully reversible if dx early enough
- Treatment: drainage of CSF fluid (V-P shunt)
- Cognitive impairment is the most resistant sx to improve with tx