Dementia Flashcards
What is dementia?
Dementia is a syndrome of generalised decline of memory, intellect and personality, without impairment of consciousness and leading to functional impairment.
What are the different types of dementia?
Briefly describe the pathophysiology and aetiology of dementia
In Alzheimer’s disease there is degeneration of cholinergic neurons in the nucleus basalis of Meynert leading to a deficiency of medulla oblongata pons acetylcholine. Other pathophysiological changes can be divided into microscopic and macroscopic:
Microscopic → Neurofibrillary tangles (intracellularly) and β-amyloid plaque formation (extracellularly).
Macroscopic → Cortical atrophy (commonly hippocampal), widened sulci and enlarged ventricles.
Give examples of irreversible causes of dementia
Neurodegenerative: Alzheimer’s disease, fronto-temporal dementia, Pick’s disease, dementia with Lewy bodies (DLB), Parkinson’s disease with dementia and Huntington’s disease.
Infections: HIV, encephalitis, syphilis and CJD.
Toxins: alcohol, barbiturates and benzodiazepines.
Vascular: vascular dementia, multi-infarct dementia and CVD.
Traumatic head injury.
Give examples of reversible causes of dementia
Neurological: normal pressure hydrocephalus, intracranial tumours and chronic subdural haematoma.
Vitamin deficiencies: B12 , folic acid, thiamine and nicotinic acid (pellagra).
Endocrine: Cushing’s syndrome and hypothyroidism.
What are the reversible and preventable causes of dementia?
Note: ‘DEMENTIA’
- Drugs (e.g. barbiturates)
- Eyes and ears (visual/hearing impairment may be confused with dementia)
- Metabolic (Cushing’s, hypothyroidism)
- Emotional (depression can present as a pseudodementia),
- Nutritional deficiencies / normal pressure hydrocephalus
- Tumours / trauma
- Infections (e.g. encephalitis)
- Alcoholism / atherosclerosis (vascular)
Briefly describe the pathophysiology and aetiology of vascular dementia (VaD)
Vascular dementia (VaD) occurs as a result of cerebrovascular disease , either due to stroke, multi-infarcts (multiple smaller unrecognized strokes) or chronic changes (arteriosclerosis) in the small vessels.
Briefly describe the pathophysiology and aetiology of Lewy body dementia (DLB)
In Lewy body dementia (DLB), there is abnormal deposition of a protein (Lewy body) within the neurons of the brainstem, substantia nigra and neocortex. Outside the brainstem LBs are associated with more profound cholinergic loss than in AD. Within the brainstem, they are associated with dopaminergic loss and parkinsonian-like symptoms.
Briefly describe the pathophysiology and artiology of frontotemporal dementia
In fronto-temporal dementia there is specific degeneration (atrophy) of the frontal and temporal lobes of the brain. One type of fronto-temporal dementia is Pick’s disease, where protein tangles (Pick’s bodies) are seen histologically.
Dementias can be divided on the basis of predominance of cortical, subcortical or mixed dysfunction.
Differentiate the location of:
- Alzheimer’s disease
- Fronto-temporal
- Lewy body dementia
- Vascular dementia
Cortical dementias include AD and fronto-temporal dementia.
Subcortical dementias include DLB.
Vascular dementia is mixed.
Briefly differentiate between cortical and subcortical dementia
Note: memory loss, mood, speech and language, personality, coordination, praxis and motor speed
How common is dementia?
There are currently 800 000 people with dementia in the UK and it is estimated that there will be over one million by 2021.
How does increasing age affect the likelihood of dementia?
Dementia increases with age (rare if <55 years; 5– 10% if >65 years; and 20% if >80 years ).
Is dementia more common in men or women?
Overall prevalence is similar in ♂ and ♀, but AD is more common in ♀, whereas vascular and mixed dementias are more common in ♂.
What are the risk factors for AD?
- Advancing age
- The incidence of AD increases with advancing age
- Family history
- The lifetime risk of AD in first degree relatives of those affected is 25– 50%
- Genetics
- Down’s syndrome
- The mutations in trisomy 21 are associated with the Down’s syndrome development of pre-senile AD
- Low IQ
- Lower educational attainment and lower IQ scores are associated with higher risks of developing dementia
- Cerebrovascular disease
- Strong risk factor for vascular dementia which can co-exist with AD
- Vascular risk factors
- E.g. Past stroke/MI, smoking, hypertension, diabetes and high cholesterol are risk factors for both AD and vascular dementia
What genes are asscociated with dementia?
There are several genes which play a role in Alzheimer’s disease:
Presenilin 1 (chromosome 14), Presenilin 2 (chromosome 2) and amyloid precursor protein (chromosome 21) are genes associated with early onset AD.
ApoE-4 (chromosome 19) is a susceptibility gene that contributes to late onset AD. The ApoE-2 variant is thought to be protective.
Briefly describe the ICD-10 Classification of dementia
A. Evidence of the following:
- A decline in memory, which is most evident in the learning of new information, although in more severe cases, the recall of previously learned information may also be affected.
- A decline in other cognitive abilities, characterised by deterioration in judgement and thinking, such as planning and organising, and in the general processing of information.
B. Preserved awareness of the environment for a period of time long enough to demonstrate (A).
C. A decline in emotional control or motivation, or a change in social behaviour, manifested by one of the following: (1) Emotional lability; (2) Irritability; (3) Apathy; (4) Coarsening of social behaviour.
D. For a confident diagnosis (A) must have been present for at least 6 months .
Briefly describe the symptomatic progression of AD
Note: early stages, disease progression and later stages
Early stages: memory lapses, difficulty finding words and forgetting names of people/places.
Disease progression: apraxia, confusion, language problems and difficulty with executive thinking.
Later stages: disorientation to time and place, wandering, apathy, incontinence, eating problems, depression and agitation.
Briefly differentiate between early and late onset AD
AD can be classified into early onset or pre-senile (<65 yrs, familial) and late onset or senile (>65 yrs, sporadic), but it usually occurs after the age of 65. It has an insidious onset over years.
What are the clinical features of AD?
Loss of memory is the commonest presenting symptom. Initially there is inability to recall new information, and remote memory (long-term memory) declines with disease progress.
Disorientation to time and place is closely related to memory impairment.
Impairment of cognitive and executive functions:
- Executive functions
- Visuospatial abilities
- Language disturbances (dysphasia)
- Apraxia
- Agnosia
Non-cognitive symptoms:
- Perception (hallucinations)
- Thought content (delusions)
- Emotion (depression, apathy)
- Behaviour (wandering, aggression, restlessness)
Briefly describe how executive functions are affected in AD
Problem solving, abstract thinking, reasoning, decision making, judgement, planning, organization and processing.
Briefly describe how visuospatial abilities are affected in AD
Getting lost, impaired driving and copying figures.
Briefly describe how language is affected in AD
Note: known as dysphagia
Word finding difficulties, decreased vocabulary, perseveration (uncontrollable repetition of a particular response, such as a word, phrase, or gesture) and global aphasia (impairment of language, affecting the production or comprehension of speech and the ability to read or write).
What is apraxia?
Note: a feature of AD
Inability to carry out previously learned purposeful movements despite normal coordination and strength e.g. dressing, unbuttoning shirt.
What is agnosia?
Note: a feature of AD
Impaired recognition of sensory stimuli not attributed to sensory loss or language disturbance e.g. object agnosia, auditory agnosia.
Briefly describe the ICD-10 Criteria of early onset AD
A. The general criteria for dementia A– D must be met.
B. No evidence for any other possible cause of dementia or systemic disorder.
Early onset Alzheimer’s disease
A. General criteria for Alzheimer’s met and age of onset is <65.
B. At least one of the following must be met:
- Relatively rapid onset and progression;
- In addition to memory impairment there is aphasia, agraphia ( ↓ ability to communicate through writing), alexia ( ↓ ability to read), acalculia ( ↓ ability to perform mathematical tasks) or apraxia .
Briefly describe the ICD-10 Criteria for late onset AD
A. The general criteria for dementia A– D must be met.
B. No evidence for any other possible cause of dementia or systemic disorder.
Late onset Alzheimer’s disease
A. General criteria for Alzheimer’s met and age of onset is >65.
B. At least one of the following must be met:
- Slow, gradual onset and progression;
- Predominance of memory impairment over intellectual impairment.
Briefly describe how vascular dementia presents
Usually presents in the late sixties or early seventies.
Stepwise rather than continuous deterioration i.e. stepwise increases in severity of symptoms.
Memory loss.
Emotional (depression, apathy) and personality changes (earlier than memory loss).
Confusion is common.
Neurological symptoms or signs (e.g. unilateral spastic weakness of the limbs or increased tendon reflexes, an extensor plantar response or pseudobulbar palsy).
On examination there may be focal neurology (often upper motor neurone signs) and signs of cardiovascular disease elsewhere.
