Epidemiology of Dementias Gerald van Belle Biostatistics and ADRC University of Washington

Outline Definition of dementia, AD Prevalence and incidence Risk factors (including protective) Assessing disease progression Why is AD research so hard? Summary

Definitions Dementia: original meaning madness Current meaning: “…global, non-reversible impairment of cerebral function with preservation of clear consciousness. It usually results in loss of memory…executive function…changes in personality.” (BMJ/CE).

Definitions Alzheimer’s disease “…insidious onset...slow deterioration…may be diagnosed after other systemic and neurological causes of dementia have been excluded clinically and by laboratory investigation.” (BMJ/CE).

Prevalence of AD South Carolina Study (Laditka et al, 2004) Rate per 1000 Age 55-64 65-84 85+ Men 3 43 338 Women 3 33 299 Eur. Am. 2 33 293 Afr. Am. 6 65 436

Prevalence of Dementia— Jorm Model Rate per 1000 person years Age Model 65-69 14 70-74 28 75-79 56 80-84 105 85-89 208 90+ 386

Incidence of Dementia Kukull et al (2002) Rate per 1000 person years Age Dementia AD 65-69 5 4 70-74 10 6 75-79 14 9 80-84 38 30 85-89 59 46 90+ 89 61

Incidence of Dementia— Jorm-like Model Rate per 1000 person years Age Model 65-69 5 70-74 8 75-79 15 80-84 28 85-89 51 90+ 93

“Risk” Factors for AD Genetic/familial Environmental Cultural Medical Other categories? Subject of lots of research

Assessing Disease Progression Activity of daily living Cognitive assessment Clinical/caregiver setting (ADL is key) Research setting (Cognitive enters) Clinical trials Disease modeling Risk factor assessment

Why is AD Research so Hard? Diagnosis by exclusion Gold standard (neuropath) is tarnished Treatments are palliative Cognitive tests are biased Slow disease progression Inability of subject to contribute detailed information Competing risks

Summary Prevalence of dementia doubles every five years. Rate at age 65 about 1 per 100 Approximately 70% of dementia is AD Very few disease-specific risk factors Disease progression research focuses on cognition AD has unique aspects