Cognitive disorders Flashcards
Definition and current prevalence rates of dementia?
An acquired syndrome consisting of a decline in memory and other cognitive functions
6-8% if older than 65
30% if older than 80
Diagnosis of dementia?
Memory impairment AND one of the following:
aphashia, apraxia, agnosia, or impaired executive functioning
Deficits cause significant impairment in social or occupational functioning
Aphasia
Characterized initially by a fluent aphasia
- Able to initiate and maintain a conversation
- Impaired comprehension
- Intact grammar and syntax however the speech is vague with paraphasias, circumlocutions, tangential, and other using nonspecific phrases (“the thing”)
Later language can be severely impaired with mutism, echolalia
Apraxia
Inability to carry out motor activities despite intact motor function
- Contributes to loss of ADLs
Agnosia
The inability to recognize or identify objects despite intact sensory function
- Typically occurs later in the course of illness
- Can be visual or tactile
Impaired executive function
Difficulty with planning, initiating, sequencing, monitoring or stopping complex behaviors
- Occurs early to midcourse
- Contributes to loss of instrumental activities of ADLs such as shopping, meal preparation, driving and managing finances
Dementia subtypes?
- Early onset: before age 60
- Less than 5% of all cases of Alzheimer’s
- Strong genetic link
- Progresses more rapidly
- Late onset: after age 60
- Majority of cases
Instrumental Activities of Daily Living (IADL’s) vs. Activities of Daily Living (ADL’s)
IADL’s are one step up from ADL’s in terms of complexity (e.g. using phone, traveling, shopping for oneself, preparing meals, taking medications, handling money)
ADL’s rudimentary tasks (e.g. bathing, dressing, grooming, toileting)
Mini-Mental Status Exam
Orientation, Registration, Attention and Calculation, Recall, Language, Visuospatial (30 pts.) = if score less than 25, consider dementia
25 is the appropriate cutoff for an 80 y/o with a high school education, so score alone does NOT determine whether individual meets criteria for diagnosis or not
MMSe pros and cons?
Pros:
- Widely used and therefore can track cognition over time and between clinicians
- 5-10 minutes
Cons:
- False positives: those with little education
- False negatives: those with high premorbid intellectual functioning
- Psychologically stressful–makes people angry!
Clock Drawing Test (CDT)
Tests planning, visuospatial abilities, but NOT memory
Less stressful, less culture-bound
Mini-Cog
Clock-Drawing Test + 3-item memory test
- More sensitive than CDT
- Same advantages as CDT
- Not as commonly used as MMSE, but fast and still quite sensitive
- Involves visuospatial, executive and planning, and memory functions
What is a “positive” Mini-Cog?
2 word recall and/or abnormal clock
Potentially reversible dementias?
Most attention given to normal pressure hydrocephalus, mass lesions, thyroid abnormalities, syphilis, and vitamin deficiencies
- Fewer than 13% of all dementia cases are reversible
- Most people do NOT return to normal or baseline cognitive functioning
- “Treatable” is more appropriate term
Labs for dementia?
Electrolytes CBC Liver enzymes TSH B12 level Syphilis?
Neuroimaging for dementia?
CT is usually adequate
MRI if vascular dementia suspected
- “Small areas of white matter ischemic changes” commonly seen in VD, but also in normals
Functional imaging not in initial workup
Alzheimer’s Disease prevalence
Most common form of dementia
Incidence age-related: 8% per year by 85 y/o
1/2 - 2/3 of all dementia is estimated to be AD
Ultimate AD diagnosis?
Autopsy:
Extracellular senile plaques surrounding beta-amyloid core throughout cortex
Intracellular neurofibrillary tangles found within neurons composed of abnormally phosphorylated Tau proteins
ACh in AD
AD is biochemically characterized by deficiency of ACh (cerebral cortex, amygdala, hippocampus)
Basal nucleus of Meynert (basal forebrain) depleted of ACh-containing neurons that project elsewhere
Genetics of AD
Minority of cases there is autosomal dominant inheritance linked to chromosome 1, 14, or 21 (associated with early onset)
Presence of allele E4 on chromosome 19 increases risk, especially if homozygous
- 34-65% of those with the allele eventually get AD
AD is probably a common manifestation of multiple underlying disorders
Course of AD
Insidious onset and progressive course with typical loss of 3 points on MMSE each year and death occurring 8-12 years after diagnosis
- Mild: MMSE 20-24, 2-3 yrs after diagnosis, primarily memory and visuospatial deficits, mild difficulty with executive functioning
- Moderate: MMSE 11-20, 3-6 yrs after diagnosis, aphasia and apraxia more pronounced, loss of IADLs and increased assistance with ADLs, start showing neuropsych symptoms (esp. paranoia)
- Severe: 6-10 yrs after diagnosis, severe language disturbances (mutism, echolalia, repetitive vocalizations), pronounced neuropsych manifestations (agitation, aggression), very late in course can see muscle rigidity, gait disturbances, incontinence, dysphagia
Vascular Dementia prevalence
Second most common form of dementia
10-40% of all dementia cases
Most common type of dementia including subtypes?
Azheimer’s Disease + Vascular Dementia
10-15% of AD cases are “mixed”
Etiology of vascular dementia?
Caused by one or more strokes
- Diagnosis reserved for patients with clear evidence of stroke on imaging or physical exam
Global vascular changes in brain
Also called “multi-infarct dementia”
