Dementia

Matthew Coulson
Note by Matthew Coulson, updated more than 1 year ago
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Description

One overarching Dementia factfile

Resource summary

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Definition: An acquired and persistent generalised disturbance of higher mental functions in an otherwise fully alert person.   Types of Dementia Primary Dementias: Arise in their own right          E.g. Alzheimer's Disease, Lewy Body Dementia & Frontotemporal                 Dementia Secondary Dementias: Arise due to an underlying condition:          E.g. Vascular Dementia Secondary dementias also include transient dementias caused by such things as infections, trauma, drugs and vitamin deficiencies (e.g. Vitamin B1).   Prevalence  The most common types of Dementia, in order: Alzheimer's Disease (60-75%) Vascular Dementia (20%) Lewy Body Dementia (10-15%) Frontotemporal Dementia (<2%)      

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Alzheimer's Disease Prevalence Alzheimer's Disease is the most common cause of dementia in the elderly, with a 40%+ prevalence in those over 85. Females:Male ratio is 2:1 Alzheimer's Disease is more likely to occur in Down's Syndrome patients, the gene encoding Amyloid Precursor Protein that is cleaved to former Beta Amyloid is found on the 21st chromosome - having three of these thus makes Alzheimer's more likely.   Pathology - Macroscopic Widening of sulci and narrowing of gyri occurs typically in the frontal, temporal and parietal lobes. The occipital lobe is typically preserved with no cortical changes observed in Alzheimer's. Ventricles tend to be dilated due to cortical atrophy. Pathology - Microscopic Gliosis: Cortical scarring - proliferation of glial cells (mainly astrocytes) Occurs in the brain due to CNS damage. Neurofibrillary Tangles: Aggregates of the Tau protein Occurs typically in the hippocampus and temporal lobe Specific indicator of Alzheimer's Disease Neuritic Plaques: Aggregates of Beta Amyloid (formed va cleavage of amyloid precursor protein) Amyloid tends to surround glial cells (mainly astrocytes and microglia)  Occurs primarily in the brain's grey matter Amyloid Angiopathy: Extracellular accumulation of eosinophils due to beta amyloid Beta amyloid stains with Congo Red stain Disrupts the blood brain barrier   Signs & Symptoms Cognition: Gradually progressive memory loss Irreversible (no day-to-day variation) Usually presents early in the disease process Challenges in solving problems Can become disorientated in terms of place, time and date Agnosia (inability to recognise objects) can occur Physical Movement: Physical deterioration does not usually occur until late in the disease process Behaviour: Doesn't tend to occur early in the disease, however facial expressions become reduced as it progresses Hallucinations: No hallucinations occur in Alzheimer's Disease patients Sleep: Tends to be unaffected in Alzheimer's Disease   Diagnosis Mini Mental State Exam: Score of ≥ 24/30 = normal cognition Score of 19-23 = mild dementia Score of 10-18 = moderate dementia Score of ≤9 = severe dementia Collaborative History is essential in deciding whether a patient shows significant cognitive and/or behavioural changes. Following this, a CT scan is first line scanning modality although this is typically normal in early dementia, CT however can show cortical atrophy (frontal, temporal and parietal lobes) in established dementia.   Treatment Currently, there are no cures for Alzheimer's Disease. There are however treatments available for those with moderate-severe Alzheimer's. Despite this, treatment via other services such as music/art therapy should be considered before pharmacological treatment, in the interest of avoiding polypharmacy in elderly patients. Cholinesterase Inhibitors (which increase the levels of acetylcholine in the brain) can be used to transiently relieve symptoms. Examples of Cholinesterase inhibitors are: Donepezil Rivastigmine Galantamine These medications slow the cognitive decline typically seen as part of Alzheimer's Disease. Side effects include nausea and diarrhoea (most common), headaches and bradycardia. They also typically worsen COPD/Asthma and peptic ulcers. Patients who does not tolerate cholinesterase inhibitors are given a medication called Memantine, which reduces the amount of glutamate in the brain. This medication also slows cognitive decline.   Other Facts A diagnosis of Alzheimer's Disease must be reported to the DVLA. The doctor will decide if the patient is allowed to drive while investigations are ongoing. The DVLA will request a report from the doctor. Basically, an Alzheimer's patient is still allowed to drive until a doctor deems them unsafe to do so.    

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Vascular Dementia Vascular dementia is a dementia caused by problems with the blood supply to the brain. Typically occurring as a series of minor strokes, it causes a step-wise decline in the cognitive ability of an individual.   Prevalence Vascular dementia is the second most common type of dementia It typically affects individuals over the age of 65; vascular dementia under the age of 65 is rather rare   Pathology Typically occurs either due to an extreme cardiovascular event (such as stroke or TIA) or a build up over atherosclerotic plaques over time, leading to ischaemia of the cortical tissues. For example, a history of stroke increases the risk of vascular dementia by 70%, and recent stroke increases the risk by 120%.  Risk factors for vascular dementia include: Age (over 65) Hypertension Hyperlipidaemia (cholesterol) Smoking Obesity Diabetes  Cardiovascular and/or cerebrovascular disease Cerebral amyloid angiopathy can also occur, leading to Alzheimer's Disease occurring alongside vascular dementia.   Signs & Symptoms Cognition: Typically, cortical function drops drastically and suddenly due to a cardiovascular event (Stroke, etc). This is described as a step wise cognitive decline as between events the cognitive function typically stays fairly constant (i.e. between the first stroke and the second the cognitive function remains constant) Dysphasia, dyscalculia, frontal lobe symptoms and affective symptoms more common than in Alzheimer's Symptoms such as memory loss, difficulty with problems solving, disorientation, etc are similar to Alzheimer's disease. The main point for vascular compared to Alzheimer's is that vascular progresses step-wise whereas Alzheimer's is a progressive cognitive decline Physical Movement: Depending on what sort of cardiovascular event a patient suffers, the physical detriment will vary. E.g. a stroke might cause weakness across one side of the body, whereas a TIA may have less major affects Physical decline tends to occur at the same time as the cognitive decline due to the likelihood that the dementia is caused by a cardiovascular event If cardiovascular event damages Wernicke's/Broca's areas then there may be some communication impediment Behaviour: Frontal lobe symptoms such as behavioural abnormalities are more common in vascular dementia patients Affect tends to be abnormal in vascular dementia patients Hallucinations: No hallucinations occur in vascular dementia patients Sleep: Tends to be unaffected in vascular dementia   Diagnosis MMSE used to assess cognitive function CT/MRI used to look for small vessel disease/infarction/haemorrhage SPECT can be useful although is used more for Frontotemporal Dementias   Treatment  Lifestyle changes to prevent further cardiovascular events eating healthy cutting down on smoking/alcohol exercising more frequently  reducing salt in diet Steps will also be taken to treat the underlying cause e.g. an individual with high cholesterol may be prescribed Atorvastatin. AHPs are also typically useful: Occupational therapists may make changes around the patient's house to make daily living easier  Physiotherapists may help with physical movement difficulties Speech and Language therapists may help with communication and/or swallowing problems Cholinesterase inhibitors are not typically used in vascular dementia, but may be useful when the disease occurs alongside Alzheimer's disease      

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Dementia with Lewy Bodies (DLB) Prevalence  Common: 10-15% of dementias DLB more commonly affects men than women   Pathology DLB is characterised by abnormal aggregations of alpha-synuclein protein inside nerve cells. The collections are known as Lewy Bodies. When alpha-synuclein builds up inside these neurons, they perform sub-optimally and eventually die. Loss of acetylcholine-producing neurons leads to memory decline and the loss of dopamine-producing neurons leads to problems of behaviour, sleep, movement and mood. DLB causes degeneration of the substantia nigra (as seen in Parkinson's Disease) leading to a pallor of this structure.   Signs & Symptoms Cognition: Main difference to Alzheimer's = Memory doesn't tend to be affected early on in Dementia with Lewy Bodies Memory tends to fluctuate; one day a patient may not remember their son's birthday, however they might remember it the next day. Alzheimer's on the other hand does not fluctuate, it is a progressive and irreversible decline Physical Movement: Difficulty walking, frequent falling and a decrease in balance are some of the earliest symptoms seen in dementia with lewy bodies Dementia with Lewy Bodies is one of the Parkinson Plus syndromes, and thus DLB patients typically develop Parkinsons-like symptoms as described above Behaviour: Flattened affect is a common symptom of DLB, this perhaps overlapping with the Parkinsonism Hallucinations: Visual hallucinations are common in Dementia with Lewy Body patients Sleep: REM Sleep Behaviour Disorder is common in DLB patients. This is when a patient acts out their dreams; they can thrash their arms around in bed, or even get up and sleep walk. Thus, always ask a patient with memory problems if they have had sleep disturbance and make sure to get a collateral history from a partner if possible.   Diagnosis Dementia with Lewy Bodies has the following diagnostic criteria: At least 2 of the following: Visual hallucinations Fluctuating cognition (delirium-like) REM sleep behaviour disorder Parkinsonism (not more than 1 year prior to onset of dementia) Positive DAT scan DAT Scan: Loflupane injected into patient followed by a SPECT scan in order to look for dopamine active transporters (DATs) in the brain.   Treatment  Only palliative care can be offered as there are no medications which will modify the course of the disease. One important thing to note is that DLB patients have seriously high risks of adverse side effects if antipsychotics are given to them. Also, anticholinergics can induce psychosis in DLB patients

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Frontotemporal Dementia Actually an umbrella term for 6 types of dementia, Frontotemporal Dementia is a progressive dementia typically commencing in middle life (usually between 50 and 60 years) characterised by progressive changes in character and social deterioration leading on to impairment of intellect, memory and language. Formerly known as Pick's disease; Pick disease is now a term used to describe one of the 6 frontotemporal dementias.   Prevalence Typical onset is between 50 and 60 years old, earlier than all of the other 3 dementias discussed here.   Pathology The general cause of frontotemporal dementia is unknown, although it is thought to be caused by accumulation of Pick Bodies (aggregates of Tau protein in nerve cells of the frontal and temporal lobes, causing them to necrose. Frontotemporal dementia is a rapidly progressive dementia which causes extreme atrophy of cerebral cortex in frontal and later in temporal lobes.   Signs & Symptoms Cognition: Memory loss does not tend to occur early on in frontotemporal dementia. If memory loss does occur, it is much later on in the disease. This is unlike Alzheimer's disease in which memory loss is the first and main symptom. Physical Movement: Not typically affected  Behaviour:             Behavioural problems are typically the hallmark of frontotemporal dementia, and occur early on in the disease. These include... Socially inappropriate behaviours Disinhibition Speech problems (very common) - non-fluent speech, articulatory errors, loss of words, etc Changes in eating habits Repetitive compulsive behavior Inability to concentrate or plan Hypersexual conversations or actions Abrupt mood changes Hallucinations: Do not occur in frontotemporal dementia Sleep: Not typically affected by frontotemporal dementia   Diagnosis Important to gain collateral history to establish behavioural change CT/MRI used to look for frontal lobe atrophy (frontal lobe atrophies before temporal lobe, typically) SPECT scan most useful in frontotemporal dementia; reduction in tracer uptake in the frontal and temporal lobes   Treatment FTD is a rapidly degenerative, incurable disease. Survival rate post diagnosis is typically 6-8 years. Treatment is purely symptomatic. Clinicians typically use antidepressants and/or antipsychotics to challenge behavioural problems. Patients also usually benefit from speech therapy in order to improve the speech impediment that usually afflicts FTD patients.

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