Epidemiology of Alzheimer’s Disease

1. Epidemiology ofAlzheimer’s Disease Carla Falkenstein, MS

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

3. What is Alzheimer’s Disease? • Neurodegenerative disease. • Most common form of dementia. • Causes impaired cognitive functioning. • No known cure.

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

5. Common Symptoms • Forgetting names and objects. • Not recognizing family & friends. • Forgetting one’s own phone number or address. • Difficulty finding a familiar place. • Noticeable language & intellectual decline.

6. Common Symptoms (cont’d) • Forgetting to eat or maintain one’s hygiene. • Poor judgment, inability to follow simple instructions. • Progressive sense of distrust. • Unusual agitation and irritability.

7. Age is a Primary Risk Factor Ages Prevalence 65-74 = 3% 75-84 = 18.7% 85+ = 47%

8. Stages of AD SEVERE 1-3 Years MODERATE 2-10 Years MILD 2-4 Years

9. Disease Process

10. Disease Process (cont’d) • 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.

11. Cause of Nerve Cell Death Amyloid Plaques? Neurofibrillary Tangles?

12. Amyloid Plaques • Insoluble deposits of beta-amyloid • Plaques found in the spaces between the brain’s nerve cells • Plaques may be a cause or a by-product of AD

13. 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.

14. Other Genetic Factors APOE є4 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.

15. AD and Other Disorders • AD has similarities with other neurodegenerative diseases: • Prion, Parkinson’s and Huntington’s diseases all cause dementia. • All involve deposits of abnormal proteins in the brain.

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

17. 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

18. A Chain of Events Leads to Disability and Death GENES LIFESTYLE & ENVIRONMENT BRAIN DEVELOPMENT & RESERVE ALZHEIMER’S SEVERITY IN BRAIN NEURO- DEGENERATION OTHER DISEASES AGE AT ONSET OF SYMPTOMS SEVERITY OF SYMPTOMS

19. 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

20. 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.

21. Global Prevalence of AD Europe There are currently an estimated 5.5 million people with dementia in Europe.

22. Global Prevalence of AD Developing Countries Currently, ~18 million people in the world have dementia. 66% of people with dementia live in developing countries.

23. 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.

24. Review Questions (Developed by the Supercourse team) • What are the major risk factors for Alzheimer’s disease? • What can be done if one has APOE e4?