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.

	Created by Matthew Coulson about 8 years ago

One overarching Dementia factfile