Alzheimer’s disease (AD) is an irreversible, progressive brain disease that slowly destroys memory and thinking skills. It is the most common type of dementia, a general term for memory loss and other cognitive abilities to impair with daily life. The patient eventually loose ability to carry out the simplest tasks. AD accounts for 60% to 80% of dementia cases.
AD is not a normal part of ageing brain, though greatest known risk factor of this disease is advancing age. The majority of patients are above 65 years of age. The disease may affect people of relatively younger age group i.e. early onset AD in 4% to 5% cases. The disease is progressive and worsen over time.
The exact cause of AD is still not known, however, it is caused by combination of genetic, lifestyle and environmental factors. In very few patients AD can be due to highly specific genetic changes that almost guarantee a person will develop this disease. The effect of AD on brain is largely known as it damages and destroys the brain cells. As more and more brain cells are destroyed, it leads to shrinkage of brain. There are two types of abnormalities in the brain that are hallmarks of this disease:
- Plaques: Plaques are clumps of protein (beta-amyloid) that damages the brain cells. These plaques are collected on the outside of brain cells.
- Tangles: Another protein called “tau” protein is present inside the brain cells that is responsible for internal support and transport system of cells. In AD these tau protein twist into abnormal shape inside the brain cells (tangles) that hampers the transport system. This failure of transport system is strongly implicated in the death of brain cells.
Patients with AD also have a shortage of some important chemicals in their brain. These chemical messengers help to transmit signals around the brain. Due to deficiency of these chemical, signals are not transmitted effectively.
Initially, mild confusion can be the only symptom in AD. Gradually, there is loss of memory, especially recent memories. Patient may first notice unusual difficulty remembering things that are noticeable to the family members. Patient with AD repeat statements and questions over and over again, forget conversation, routinely misplace common possessions, get lost in familiar places, forget the names of family members and forget words to identify objects.
The patient with AD has difficulty in concentrating and thinking, making judgements and decisions, planning and performing familiar tasks. Further, AD also affect the changes in personalities and behaviour of the patient. Patients with AD may experience depression, apathy, social withdrawal, mood swings, lack of trust, irritability and aggressiveness, sleeping troubles, purposeless wandering, loss of inhibitions, delusions.
Interestingly, many skills are not lost until very late in the disease like reading, singing, craft and hobbies.
AD can be categorized into 4 stages as follows:
- Pre-dementia: Initial symptoms are mistaken with ageing or stress. The early symptoms can affect activities of daily living. There is short term memory loss, shows difficulty in remembering recently learned facts and inability to acquire new information.
- Early Disease: Leads to definitive diagnosis. Decreased vocabulary and decreased word fluency.
- Moderate Disease: Progressive deterioration hinders independence, with patients unable to perform common activities. Speech difficulty become evident. Patient may fail to recognize close relatives and family members. There may be irritability, crying, aggression or resistance to care giving.
- Advanced: The patient is completely dependent on caregivers. Almost complete loss of speech. This stage is potentially serious as patient is vulnerable to infections, pressure ulcers and other complications that may lead to death. Patient may have falls, fractures and malnutrition.
- Age: The rate of dementia doubles every decade after the age of 60. People with rare genetic changes may develop early onset AD as early as their 30s.
- Family history: The risk is higher if parents or any of the sibling has the disease.
- Down syndrome: Many people with Down syndrome develop AD. The disease tend to appear 10-20 years earlier in patients with Down syndrome.
- Sex: Female are more prone to develop AD than males.
- Mild cognitive impairment (MCI): People with mild cognitive dysfunction has greater chance of developing AD in later phase of life.
- Head injury: Persons with past head injury have higher risk of developing AD than people without history of head trauma.
- Cardiac health: Factor that increase the risk of heart diseases also makes person prone for AD. These include lack of exercise, obesity, smoking, high blood pressure, high cholesterol, diabetes, poor diet.
- Lack of education: Low education levels increases the risk of AD
- Poor social engagement: People with isolated living, poor social networks or other engagements are prone to AD.
There is no proven strategy to prevent AD. However, certain factors that reduce the risk of heart disease also decrease the chances of developing AD. The healthy dietary habits with fresh produce, healthy oils, low fats, can lower the risk of AD. People should be advised to remain active physically, mentally and socially till their lives.
No specific test is available that confirms AD. The diagnosis is essentially made by symptoms and clinical evaluation of neurological functions like reflexes, tone, coordination etc. Laboratory tests are done to exclude any other cause of dementia like vitamin deficiency or thyroid disorders.
The patients are assessed by brief mental status test for memory and thinking skills. Brain imaging are done to identify any visible abnormalities like stroke, trauma, tumours etc. These include MRI, CT scan and PET.
Future tools for diagnosis of AD are under investigation and include specific forms of brain imaging, specific biomarkers in blood or cerebrospinal fluid (CSF).
The available drug treatment for AD is aimed to enhance memory function and other cognitive changes. Two types of drugs that are commonly used in AD are:
- Cholinesterase inhibitors: These drugs enhance the communication between the brain cells by providing a neurochemical (acetylcholine). These drugs also help improve the symptoms of agitation and depression in patients with AD.
- NMDA antagonist: This specific drugs blocks a particular site (NMDA) in the brain that help enhance the cell functions. It is used in the treatment of moderate to severe cases of AD and can be combined with cholinesterase inhibitors as well.
There are several biological agents (monoclonal antibodies) targeted against specific protein are under development for the treatment of AD.
Besides these specific drugs for AD, other drugs that are used to alleviate the behavioural symptoms include anti-depressants, anti-anxiety and few sleep medications. An important point to note for all patients with AD is creation of a safe and supportive environment for their quality living. These are keeping all essential valuables at home, carry mobile with patient, use of calendar or diary for notes, remove clutters at home, keep photos and meaningful at home.
Patients with AD should be encouraged to do regular exercise, take adequate nutrition, and engage on various mental and social activities. There are several “brain gyms” to stimulate the brain functions and help in prevention and alleviation of AD.
Various alternative medicines are being used to enhance and promote memory and cognitive functions. There is no strong evidence for these to slow progression of the disease. Some of the treatment that are sometimes used and widely discussed for AD are as follows:
- Omega-3 fatty acid found in fish oil
- Curcumin from turmeric with anti-inflammatory and anti-oxidant actions.
- Ginkgo: Plant extract
- Vitamin E: Mixed results in clinical studies. Dosage as high as 2000 IU daily may delay in progression of the disease.
Support to Caregiver:
Person providing care and support to patients with AD feel usually feel physically and emotionally exhausted. It is very demanding for caregiver taking care round the clock. Caregiver may feel irritated, stressed, discouraged and socially isolated. It can affect the physical health significantly. Some of the tips for caregivers are learning about the disease, involve healthcare persons and social workers in discussion, take break every day, spend some time with your friend, join a support group, and take care of physical health.