Dementias Flashcards
What is Vascular (multi-infarct) dementia?
Loss of cognitive functioning due to disruption of blood supply to the brain, e.g., a series of small ‘strokes’.
What are the causes of Vascular (multi-infarct) dementia?
Strokes deprive the brain of oxygen and nutrients. Cells die, leading to areas of cell loss (‘lesions’ or ‘infarcts’). Neurones die, ‘holes’ develop in the brain
Each small stroke causes a further deterioration.
Risk factors in Vascular dementia and how to prevent it
Many patients have a history of hypertension (high blood pressure).
Other risk factors include smoking, diabetes and high cholesterol.
Symptoms can appear suddenly (e.g., after a mini-stroke) and then show “stepped” progression
Progression can be slowed by improving cardiovascular function
What are the symptoms of Vascular (multi-infarct) dementia?
Problems with concentration and acute confusion
Problems with organising complex thought and behaviour
Behavioural symptoms: apathy, restlessness
Physical weakness/paralysis (symptoms associated with frontal stroke)
What is a stroke?
A disruption to the supply of blood to the brain caused by: blocked artery (e.g. a blood clot: thrombosis) or bleed into the brain from a burst artery (haemorrhage)
What are focal dementias?
When damage is restricted to limited parts of the cortex before eventually becoming more widespread
In Alzheimer’s, pathology and atrophy is usually widespread, affecting temporal, parietal and frontal lobes.
What is frontotemporal dementia? (FTD)
Rare overall but more common in younger people; typically diagnosed between 45 and 65 years of age
Different pathology from AD – No amyloid plaques. Sometimes there are “Pick bodies” inside cells (clumps of tau protein).
Different forms, depending on where the atrophy is:
Frontal variant (in 70% of cases): atrophy in frontal lobes
Semantic dementia: Atrophy in anterior temporal lobes
Often a mixture of symptoms; start out different but become similar over time
What is frontal variant FTD and what are the symptoms?
(Form of frontotemporal dementia)
Frontal degeneration in frontotemporal dementia (FTD) causes:
Personality changes: rudeness, apathy, impatience.
Lack of inhibition; inappropriate language and behaviour.
Loss of empathy.
Compulsive/ritualised behaviour – obsessions with time/numbers; hoarding.
Overeating; preference for sweet foods.
What are the symptoms of Semantic dementia and where is the atrophy found?
(Form of frontotemporal dementia)
Produces problems with semantic memory
Atrophy in the anterior temporal lobes
Progressive loss of conceptual knowledge, accessed from both words and pictures
Still have good language skills and memory of recent events
Good non-verbal reasoning
Atrophy not on hippocampus
What is posterior cortical atrophy?
AD like pathology
Affects posterior parietal cortex
What are the symptoms of posterior cortical atrophy?
blurred vision; light sensitivity.
progressive inability to recognise faces and objects (“agnosia”).
problems with spatial skills such as dressing or driving.
impaired reading and writing.
memory, spoken language and thinking preserved until late stages
What are subcortical dementias? + 2 examples
Basal ganglia: subcortical structures involved in starting and stopping movements (and thoughts). Subcortical dementias that impair the functioning of these structures affect movement (and cognitive) control.
Huntington’s disease – excessive movement (inhibitory failure)
Parkinson’s disease – problems initiating movements
Huntingtons disease
Rare (0.01%) genetic disorder causing loss of neurons in subcortical areas
Results from mutation of a single gene on chromosome 4. Dominant, therefore 50% chance of inheritance.
Prominent early changes in basal ganglia, then cortical atrophy
First symptoms usually occur at age 30 - 45.
Restlessness of the face, fingers and feet.
Clumsiness
Involuntary and excessive movement (hyperkinesia): especially chorea – uncontrollable jerky, writhing movements.
Cognitive changes: poor concentration, working memory, executive functions
Emotional changes: aggression; anti-social behaviour; low or changeable mood; irritability; lack of emotion
Eventually problems eating, swallowing and speaking
Basal ganglia inhibits thalamus-to-cortex connections. HD causes breakdown in this inhibitory pathway, affecting motor, cognitive and emotional control
Woody Guthrie (1912-1967) - Began to show symptoms in the 1940s. Diagnosed
as “alcoholism” and “schizophrenia”. Correct diagnosis only in 1952. Increased awareness following his death.
Huntington’s disease – insufficient inhibition within thalamo-cortical circuits
Parkinsons disease
Affects around 1% of 60-year-olds and > 2% of 85-year-olds.
Causes are not known. Less heritable than many other dementias.
Degeneration in a part of the basal ganglia (substantia nigra) causes deficit in neuromodulator dopamine.
Dopamine normally suppresses inhibitory loop – it releases movement.
Dopamine deficit in PD makes it hard to initiate movement.
Symptoms develop slowly. No clinical symptoms until dopamine levels have dropped by 80% (compensation by remaining cells).
Treatment with levodopa is aimed at boosting dopamine levels, over time it gets harder to get dosage correct
Parkinson’s disease – loss of dopamine: Loss of control of inhibition
Negative symptoms of subcortical dementias
Loss of spontaneous movement (akinesia).
Unable to generate movements voluntarily (including facial expressions - ‘mask face’). Are able to respond to external visual stimuli.
Slowness in movement (bradykinesia).
Marked slowing of repetitive movements, including tapping or clapping.
Disturbed speech. Bradykinesia affects speech which can be slow, and difficult to understand.
