Alzheimer’s Disease (AD) is a chronic, irreversible disease affecting the brain, leading to progressive memory loss and difficulty in functioning independently. It is the most common type of dementia. In dementia, a person develops difficulty with memory, language, ability to think and organise themselves, leading to functional dependence.
About 10% of individuals over the age of 70 have some form of memory loss and half of these patients tend to have AD. It is estimated that more than 5.5 million Americans are likely suffering from AD leading to significant morbidity and financial burden. The cost of care for a patient with advanced AD is greater than $50,000 per year.
AD is caused by the accumulation of plaques made of amyloid protein and tangles made of tau protein. These can be observed by examining the brain under a microscope.
Risk Factors for Alzheimer’s Disease
- Old Age, especially over 70 years
- Family History of AD: Several genetic forms exist with earlier onset of AD
- Down’s Syndrome: The extra chromosome causing Down’s also bears the gene for the amyloid protein leading to its excess. Down’s patients surviving over the age of 40 commonly develop AD.
Signs and symptoms of Alzheimer’s Disease
Early disease is characterised by memory loss, referred to as mild cognitive impairment (MCI). About 50% of individuals with MCI will progress to full blown AD in approximately 4 years.
- Memory Loss: This begins with mild difficulty remembering names or words, which progresses to inability to remember life events and failure to recognize friends and family.
- Visuo-spatial deficits: This refers to difficulty in navigating through the neighbourhood and their homes. They tend to to lose their way and driving becomes dangerous.
- Difficulty planning and organising daily tasks: Paying bills and handling money becomes a problem. Longer time is spent on day to day activities like cooking and cleaning.
- Impaired judgement, reasoning and ability to make decisions.
- Personality changes: The person may also show changes in behaviour and personality, including anger or frustration when they realise their deficits and also due to other overlapping dementias characterised by altered personality.
- Depression: In early stages, awareness of one’s own deficits can lead to low mood and depression. (Depression by itself can also lead to perceived memory loss which may not be AD.)
- Functional disability: In late stages, even simple tasks like bathing, eating and using the toilet require assistance.
Diagnosis of Alzheimer’s Disease
The only definitive test to diagnose AD is by examining brain tissue obtained through a biopsy to look for amyloid plaques and tau protein tangles. However, as this is an invasive test with potential for additional damage to the brain, a clinical diagnosis is routinely made based on history of progressive memory loss and functional impairment occurring over several years. Additional tests are done to further characterise the disease severity and to rule out other diseases.
- Mini Mental State Exam: This involves a series of questions to gauge the cognitive function of the person. It can be used to monitor a person’s cognitive ability over time.
- Neurological Exam: This is done to rule out any structural damage to the brain in the form of a stroke and to look for signs of other neurological diseases like Parkinson’s disease.
- Blood Investigations: Complete blood count, electrolytes, thyroid function and vitamin B12 levels are measured as derangements can cause conditions which mimic AD.
- Imaging of the Head: Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) are recommended to look for any structural changes in the brain.
Management of Alzheimer’s Disease
There is no cure for AD. A few drugs have been approved for use and have shown moderate benefits in slowing cognitive decline. For the most part, however, the management of a patient with AD involves supportive care. Caregivers also require counseling and psychological support to prevent burn out as caring for a patient with AD can be physically and emotionally demanding.
- Cholinesterase inhibitors: these drugs prevent breakdown of acetylcholine in the brain which is shown to improve memory. E.g.: donepezil, rivastigmine, galantamine
- NMDA receptor blocker: Memantine is a drug which blocks the N-methyl-D-aspartate channels which is found to be beneficial.
- Antidepressants: These help with depression encountered in early disease
- Antipsychotics: These medications may be required in case of significant agitation. However, they have numerous side effects in the elderly and should be taken with caution.
Functional Aids and Precautions
- Notes and daily reminders of tasks to be completed can help the patient
- Signs indicating different rooms around the house can help with navigation
- Bracelets with the patient’s name and address should be worn in case he or she wanders out and loses the way home.
- Driving should be stopped.
- Bathrooms, kitchens, and bedrooms must be made safe to prevent falls, fires, and other accidents.
- In late stages, a full-time caregiver may be needed to assist with all activities and nursing home placement should be considered.
Counseling and Support for Caregivers
Prognosis of Alzheimers’s Disease
The disease progresses gradually over many years, typically over 8 to 10 years but can take anywhere from 1 to 25 years. There is no cure and eventually, patients will become, bed-ridden and mute, requiring assistance with the simplest tasks like eating, dressing, and using the toilet. The most common cause of death is from aspiration of food or saliva into the lungs with subsequent infection. Malnutrition falls, pulmonary embolism (from clots in the legs developing from immobility) and heart disease are other causes of death.