Epidemiology of Alzheimer

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Epidemiology ofAlzheimers Disease
Carla Falkenstein, MS
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Course Content

• Description of the disease process.
• Possible etiology based on population studies.
• Global prevalence.

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What is Alzheimers Disease?

• Neurodegenerative disease.
• Most common form of dementia.
• Causes impaired cognitive functioning.
• No known cure.

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Diagnosis of AD

• Because it is a progressive disease with one of
  the earliest symptoms being memory loss,
  diagnosis is difficult.

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Common Symptoms

• Forgetting names and objects.
• Not recognizing family friends.
• Forgetting ones own phone number or address.
• Difficulty finding a familiar place.
• Noticeable language intellectual decline.

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Common Symptoms (contd)

• Forgetting to eat or maintain ones hygiene.
• Poor judgment, inability to follow simple
  instructions.
• Progressive sense of distrust.
• Unusual agitation and irritability.

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Age is a Primary Risk Factor
Ages Prevalence 65-74 3 75-84 18.7 85
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Stages of AD
SEVERE 1-3 Years
MODERATE 2-10 Years
MILD 2-4 Years
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Disease Process
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Disease Process (contd)

• 1st destroys neurons in parts of the brain that
  control memory.
• Later attacks cerebral cortex - areas responsible
  for language and reasoning.
• Eventually nearly the entire brain is atrophied.

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Cause of Nerve Cell Death

• Amyloid Plaques?
• Neurofibrillary Tangles?

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Amyloid Plaques

• Insoluble deposits of beta-amyloid
• Plaques found in the spaces between the brains
  nerve cells
• Plaques may be a cause or a by-product of AD

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Neurofibrillary Tangles

• Twisted threads of a protein called tau.
• Tau is a protein found inside nerve cells.
• In AD, Tau changes so that it becomes 2 threads
  wound around each other.

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Other Genetic Factors
APOE ?4 allele of the APOE gene is a major risk
factor for late-onset AD. However, much work is
being done to sort out all the potential genetic
factors involved in AD.
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AD and Other Disorders

• AD has similarities with other neurodegenerative
  diseases
• Prion, Parkinsons and Huntingtons diseases all
  cause dementia.
• All involve deposits of abnormal proteins in the
  brain.

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Early Diagnosis

• The earlier a correct diagnosis can be made, the
  greater the gain in managing symptoms through
  pharmaceuticals.
• MRI
• PET
• SPECT

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Causal vs. Associative Agents

• Advanced age
• Female gender
• Head Injury
• Cerebrovascular disease
• Low education levels
• Rural Residence
• Blood cholesterol
• Low blood levels of folic acid
• Inflammation

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A Chain of Events Leads to
Disability and Death
GENES
LIFESTYLE ENVIRONMENT
BRAIN DEVELOPMENT RESERVE
ALZHEIMERS SEVERITY IN BRAIN
NEURO- DEGENERATION
OTHER DISEASES
AGE AT ONSET OF SYMPTOMS
SEVERITY OF SYMPTOMS
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Global Prevalence of AD

• United States
• Most common cause of AD
• Current cases 4 million
• Prevalence doubles every 5 years beyond age 65
• Nearly 50 of those aged 85 have AD

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Global Prevalence of AD

• African Americans in Indianapolis are twice as
  likely as Africans in Ibadan, Nigeria to develop
  dementia AD.
• Higher rates of AD in Japanese men who emigrated
  to US compared with those who remained in Japan.

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Global Prevalence of AD
Europe There are currently an estimated 5.5
million people with dementia in Europe.
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Global Prevalence of AD
Developing Countries Currently, 18 million
people in the world have dementia. 66 of
people with dementia live in developing countries.
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Current Research

• Continued search for causative agents and
  etiology.
• Disease prevalence worldwide with close attention
  to cultural variations.
• Animal and population studies that confirm
  causation and lead to preventive or curative
  measures.

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Review Questions (Developed by the Supercourse
team)

• What are the major risk factors for Alzheimers
  disease?
• What can be done if one has APOE e4?