Authors :Dr.Praveen Gupta

It affects just over a tenth of people in the over-65 age group in the US. In the over-85s, the proportion goes up to about a third. The Alzheimer's Association says it accounts for between 60% and 80% of all cases of dementia. Vascular dementia, which is caused by stroke not Alzheimer's is the next most common type of dementia.

Cause

Like all types of dementia Alzheimer's is caused by brain cell death.3 It is a neurodegenerative disease, which means there is progressive brain cell death that happens over a course of time. The total brain size shrinks with Alzheimer's - the tissue has progressively fewer nerve cells and connections.

Changes in nerve cells (neurons) in the brain in Alzheimer's : there are microscopic 'plaques' and 'tangles' between and within brain cells. Plaques are found between the dying cells in the brain - from the build-up of a protein called beta-amyloid (you may hear the term "amyloid plaques"). The tangles are within the brain neurons - from a disintegration of another protein, called tau.

Risk factors

Risk factors associated with Alzheimer's disease include:

Unavoidable risk factors
  • Age - the disorder is more likely in older people, and a greater proportion of over-85-year-olds have it than of over-65s.
  • Family history (inheritance of genes) - having Alzheimer's in the family is associated with higher risk. This is the second biggest risk factor after age
  • Having a certain gene (the apolipoprotein E or APOE gene) puts a person, depending on their specific genetics, at three to eight times more risk than a person without the gene. Numerous other genes have been found to be associated with Alzheimer's disease, even recently (see developments below).
  • Being female (more women than men are affected).


Potentially avoidable or modifiable factors

  • Factors that increase blood vessel (vascular) risk - including diabetes, high cholesterol and hypertension .these also increase the risk of stroke, which itself can lead to another type of dementia.)
  • Low educational and occupational attainment.
  • Prior head injury. (While a head injury does not necessarily lead to Alzheimer's, some research links have been drawn, with increasing risk tied to the severity of trauma history.)
  • Sleep disorders (the breathing problem sleep apnea, for example).
  • Hormone replacement therapy


Signs and symptoms

Dementia involves cognitive or behavioral symptoms that show a decline from previous levels of "functioning and performing" and interfere with ability "to function at work or at usual activities."

The cognitive decline is in at least TWO of the five symptom areas listed below

1. Worsened ability to take in and remember new information, for example:

  • "Repetitive questions or conversations
  • Misplacing personal belongings
  • Forgetting events or appointments
  • Getting lost on a familiar route."


2. Impairments to reasoning, complex tasking, exercising judgment:

  • Poor understanding of safety risks
  • Inability to manage finances
  • Poor decision-making ability
  • Inability to plan complex or sequential activities."


3. Impaired visuospatial abilities (but not, for example, due to eye sight problems):

  • "Inability to recognize faces or common objects or to find objects in direct view
  • Inability to operate simple implements, or orient clothing to the body."


4. Impaired speaking, reading and writing:

  • Difficulty thinking of common words while speaking, hesitations
  • Speech, spelling, and writing errors."


5. Changes in personality and behavior, for example:

  • Out-of-character mood changes, including agitation; less interest, motivation or initiative; apathy; social withdrawal Loss of empathy
  • Compulsive, obsessive or socially unacceptable behavior.


Once the number and severity of the above symptoms confirm dementia, the best certainty that they are because of Alzheimer's disease is given by:

  • A gradual onset "over months to years" rather than hours or days (the case with some other problems)
  • A marked worsening of the individual person's normal level of cognition in particular areas.(11)


The most common presentation marking Alzheimer's dementia is where symptoms of memory loss are the most prominent, especially in the area of learning and recalling new information. The initial presentation can also be one of mainly language problems, in which case the greatest symptom is struggling to find the right words.

If visuospatial deficits are most prominent, meanwhile, these would include inability to recognize objects and faces, to comprehend separate parts of a scene at once (simultanagnosia), and a type of difficulty with reading text (alexia). Finally, the most prominent deficits in "executive dysfunction" would be to do with reasoning, judgment and problem-solving.

Stages of Alzheimer's disease
    The progression of Alzheimer's can be broken down into three basic stages:
  • Preclinical (no signs or symptoms yet)
  • Mild cognitive impairment
  • Dementia


The Alzheimer's Association has broken this down further, describing seven stages along a continuum of cognitive decline based on symptom severity - from a state of no impairment, through mild and moderate decline, and eventually reaching "very severe decline."

Tests and diagnosis Alzheimer's disease is not simple to diagnose - there is no single test for it. For this reason, the first thing doctors do is to rule out other problems before confirming whether mental signs and symptoms are severe enough to be a kind of dementia or something else.The tests include tests of blood and urine samples and brain scans (possibly including CT, MRI and EEG). And sometime functional neuroimaging

There must be memory loss and an impairment in one other area of cognition for a diagnosis of dementia such as Alzheimer's to be made. These criteria also need to be progressive (a worsening compared with how the person has been before), and severe enough to affect daily activities.(11)

The mini mental state examination (MMSE) is a common cognitive test to help diagnose Alzheimer's disease. It is also sensitive to the severity of the disorder and helps to indicate when drug treatment could ease symptoms appearing later in the course of the disease(8)

  • ormal cognitive health - score above 26
  • Mild-to-moderate Alzheimer's - below 26
  • Moderate - below 20 but above 10
  • Severe - score under 10.


There is no simple biological test specifically for Alzheimer's disease that can be used by doctors, which is why all the diagnostic options are designed to rule out other explanations for the dementia before confirming Alzheimer's as the cause.

Treatment and prevention

There is no known cure for Alzheimer's disease - the death of brain cells in the dementia cannot be halted or reversed.

Drug therapy

There are no disease-modifying drugs available for Alzheimer's disease but some options may reduce its symptoms and help improve quality of life. There are drugs in a class called cholinesterase inhibitor approved for symptomatic relief like Donepezil and Rivastigmine.A different kind of drug, memantine , an NMDA receptor antagonist, may also be used, alone or in combination with a cholinesterase inhibitor.

Other therapy

A major part of therapy for patients with Alzheimer's comes from the support given by healthcare workers to provide dementia quality-of-life care, which becomes more important as needs increase with declining independence.