Define dementia - ANSWER - Dementia is a syndrome and not a single disease entity.
- It refers to progressive impairment of higher cortical functions, including memory, orientation, comprehension, calculation, learning
...
Define dementia - ANSWER - Dementia is a syndrome and not a single disease entity.
- It refers to progressive impairment of higher cortical functions, including memory, orientation, comprehension, calculation, learning capacity, language and judgement.
- The dominant symptoms depend on the brain region most affected by disease.
- Often it is accompanied, or preceded by, deterioration in emotional control, social behaviour or motivation.
- In the initial stages, there are often focal cortical deficits, and as it progresses it is eventually associated with diffuse involvement of both cerebral hemispheres.
Difference between dementia and delirium - ANSWER - The patient is often alert in the early and middle stages of the disease.
- This is in contrast to delirium (acute confusional state), in which alteration of level of consciousness is a defining feature.
Dementia vs. delirum vs. depression - ANSWER
Epidemiology of dementia - ANSWER - The most common causes of dementia are Alzheimer's disease and vascular dementia, and these are predominantly diseases of the elderly.
- 50-70 years old prevalence is 1%
- 90years old prevalence is 50%
What determines rate of decline in dementia? - ANSWER The cause.
• Alzheimer's disease: slowly progressive over years
• Vascular dementia: repeated large vessel occlusion causes stepwise deterioration, whereas small vessel disease causes a progressive decline without steps. Both often coexist
• Prion disease or a CNS vasculitis: progressive over months
• Encephalitis: over days to weeks
• It should be noted that all dementias tend to be accelerated by a change in environment, intercurrent infection or surgical procedures.
Symptoms of dementia - ANSWER - The earliest symptoms correlate with area of the brain first affected
- As disease spreads through the brain, other symptoms develop.
- Therefore, in Alzheimer's disease, recent memory impairment is the most common initial complaint and reflects early degeneration of the hippocampal areas.
- In frontotemporal dementia, changes in personality can often be reported, reflecting early involvement of frontal structures
Ix - ANSWER - Routine bloods: TFT, B12, folate, syphilis
- Special (to screen rarer causes of dementia) metabolic disorders (ex. wilson's), leucodystrophies, HIV ('AIDS dementia' ), vasculitis and inflammatory diseases, limbic encephalitis.
- LP in those under 65 years to exclude treatable causes of dementia
However...
- The CSF levels of tau (increased) and a beta 42 (decreased) can sometimes help with the diagnosis of Alzheimer's disease, but tend to be measured only in specialist centres.
- Similarly, elevated S100 and protein 14-3-3 are supportive of a diagnosis of CJD.
- Neuropsychometry
- EEG: may find widespread delta waves, especially in early alzheimers. Alzheimers also shows loss of responsive alpha rhythm (as opposed to FTLD). Periodic complexes may indicate CJD.
Imaging - ANSWER - Typically, variable degrees of cerebral atrophy with enlarged ventricles are seen with most forms of dementia.
- However, MRI can also be used to allow assessment of signal change and patterns of atrophy consistent with specific forms of dementia. - For example increased T2 signal in the thalami is characteristic of variant Creutzfeldt- Jakob disease (CJD).
- Bilateral hippocampal and temporal lobe atrophy is seen in Alzheimer's disease and asymmetrical anterior hippocampal, amygdala and temporal lobe atrophy is seen in frontotemporal lobar degeneration (FTLD).
- In cerebrovascular disease imaging can demonstrate multiple infarcts or significant small vessel disease.
genetic testing - ANSWER - Huntington mutation: Huntington's chorea
- Alzheimer's disease: amyloid precursor protein (APP), presenilin 1 and 2, and apoliprotein E4 mutations familial
- Creutzfeldt- Jakob disease: prion protein gene mutation
- FTLD: tau, progranulin and C9orf72 mutations.
Epidemiology of Alzheimer's - ANSWER - Alzheimer's disease is the most common cause of dementia in the developed world.
- There are approximately 500 000 cases in the UK at any one time.
- It is rarely seen in persons under the age of 45 years, except in familial cases, and the incidence increases dramatically with age, especially in patients over 70 years. .
Genetics of Alzheimer's - ANSWER - Familial Alzheimer's disease is rare.
- Mutations in the amyloid precursor protein (APP) gene on chromosome 21, presenilin 1 and 2 genes is associated with young onset AD.
- There is also an association of late-onset disease with the apolipoprotein E4 genotype.
- Individuals with Down syndrome develop the full neuropathological and clinical changes of Alzheimer's disease by their fourth to fifth decade of life, probably as a consequence of the excessive APP produced by a 50% increase in gene dosage due to the extra chromosome 21
Pathophysiology of Alzheimer's - ANSWER - presence of extracellular amyloid plaques and intracellular neurofibrillary tangles in the brain.
- The plaques consist of dystrophic neurites clustered round a core of b -amyloid protein, which is derived from the larger precursor protein, APP.
- Amyloid can also be deposited in cerebral blood vessels, leading to amyloid angiopathy.
- Neurofibrillary tangles are derived from the micro-tubule-associated protein tau, which is in an abnormally hyperphosphorylated state and causes protein aggregation.
- The majority of the pathology affects the hippocampus, temporal and parietal lobes.
- Typically, the primary motor and sensory cortex are spared.
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