Dementias Flashcards
What is the definition of dementia?
Clinical syndrome caused by a number of brain disorders which cause memory loss, decline in some other aspects of cognition, and difficulties with activities of living.
What are some types of dementia?
Alzheimer’s disease (50-70%)
Vascular dementia (25%)
Dementia with Lewy bodies (15%)
Frontotemporal dementia (<5%)
Potentially treatable dementias (<5%)
Huntington’s disease (rare)
Parkinson’s dementia (rare)
CJD (rare)
What are some potentially treatable dementias?
Metabolic (eg uraemia)
Toxic (eg alcohol)
Vitamin deficiency (B12 and thiamine)
Traumatic
Intracranial lesions
Infections (eg HIV)
Endocrine (eg hypothyroidism)
Psychiatric (pseudodementia)
What is the pathophysiology of Alzheimer’s disease?
Loss of cortical neurones
Neurofibrillary tangles
Senile plaques (extracellular protein deposits containing beta amyloid)
What genes are involved in Alzheimer’s disease?
E4 allele of apolipoprotein E gene
Point mutations in APP gene
Mutations in presenilin 1 and 2
What is the pathophysiology of Huntington’s disease?
CAG repeat encoding poly-glutamine that has toxic effect on cells, resulting in neuronal loss
Caudate atrophy with loss of cells from basal ganglia and cerebral cortex
What genetic phenomenon does Huntington’s have?
Anticipation - number of repeats increases over generations, so symptoms will develop sooner in each successive generation
What is the pathophysiology of dementia with Lewy bodies?
Accumulation of Lewy bodies (inclusions composed of protein alpha-synuclein, a cytoplasmic protein associated with synaptic vesicles)
What are the clinical features of Alzheimer’s disease?
Gradual onset decline of short-term memory
Autobiographical and political memory often well preserved
Poor concentration, poor sleep, low mood
End stages - hallucinations, poor dentition, skin ulcers, loss of verbal communication
Atypical presentations - visuospatial disturbance, progressive primary aphasia
What are some clinical features of vascular dementia?
Dysphasia, dyscalculia, frontal lobe symptoms and affective symptoms
Focal neurological signs
Vascular risk factors
Step wise decline
What are some clinical features of frontotemporal dementia?
Behavioural variant (behavioural changes, executive dysfunction, disinhibition, loss of social skills, apathy, obsessions, change in diet)
Primary progressive aphasia (effortful non-fluent speech, articulatory errors, lack of grammar/words)
Semantic dementia (impaired understanding of meaning of words, fluent but empty speech, difficulty retrieving names)
What are some clinical features of dementia with Lewy bodies?
Visual hallucinations
Fluctuating cognition (delirium like)
REM sleep behaviour disorder
Extrapyramidal features (Parkinsonism) - not more than 1 year prior to onset of dementia
Positive DAT scan
What are some clinical features of dementia in Parkinson’s disease?
80% after 15-20 years of Parkinson’s disease
Must have Parkinsonism for at least 1 year prior to onset of dementia
Clinical presentation similar to DLB
What are some clinical features of Huntington’s disease?
Involuntary movements
Dementia
Decline in executive function
Short and long term memory deficits
Anxiety, psychosis, compulsions, suicidality, aggression, blunted affect
Late signs: rigidity, bradykinesia, serious weight loss, inability to walk or speak, swallowing problems
What are some investigations for dementia?
Cognitive testing with history (ACE-III, MoCA)
CT (current standard)
MRI (if young, fast progression or atypical)
SPECT (useful for frontotemporal and clarifying Alzheimer’s diagnosis)
DAT (suspected DLB/DPD when patient doesn’t have enough supporting features for diagnostic certainty)
