The Prevalence and Incidence of Dementia: a Systematic Review and Meta-analysis.
Introduction Dementia is a common neurological condition affecting many older individuals that leads to a loss of independence, diminished quality of life, premature mortality, caregiver burden and high levels of healthcare utilization and cost. This is an updated systematic review and meta-analysis of the worldwide prevalence and incidence of dementia.


METHODS
The MEDLINE and EMBASE databases were searched for relevant studies published between 2000 (1985 for Canadian papers) and July of 2012. Papers selected for full-text review were included in the systematic review if they provided an original population-based estimate for the incidence and/or prevalence of dementia. The reference lists of included articles were also searched for additional studies. Two individuals independently performed abstract and full-text review, data extraction, and quality assessment of the papers. Random-effects models and/or meta-regression were used to generate pooled estimates by age, sex, setting (i.e., community, institution, both), diagnostic criteria utilized, location (i.e., continent) and year of data collection.


RESULTS
Of 16,066 abstracts screened, 707 articles were selected for full-text review. A total of 160 studies met the inclusion criteria. Among individuals 60 and over residing in the community, the pooled point and annual period prevalence estimates of dementia were 48.62 (CI95%: 41.98-56.32) and 69.07 (CI95%: 52.36-91.11) per 1000 persons, respectively. The respective pooled incidence rate (same age and setting) was 17.18 (CI95%: 13.90-21.23) per 1000 person-years, while the annual incidence proportion was 52.85 (CI95%: 33.08-84.42) per 1,000 persons. Increasing participant age was associated with a higher dementia prevalence and incidence. Annual period prevalence was higher in North America than in South America, Europe and Asia (in order of decreasing period prevalence) and higher in institutional compared to community and combined settings. Sex, diagnostic criteria (except for incidence proportion) and year of data collection were not associated with statistically significant different estimates of prevalence or incidence, though estimates were consistently higher for females than males.


CONCLUSIONS
Dementia is a common neurological condition in older individuals. Significant gaps in knowledge about its epidemiology were identified, particularly with regard to the incidence of dementia in low- and middle-income countries. Accurate estimates of prevalence and incidence of dementia are needed to plan for the health and social services that will be required to deal with an aging population.
1Department of Clinical Neurosciences,University of Calgary,Calgary,Alberta,Canada.
Kirsten M
KM
Fiest
1Department of Clinical Neurosciences,University of Calgary,Calgary,Alberta,Canada.
Nathalie
N
Jetté
1Department of Clinical Neurosciences,University of Calgary,Calgary,Alberta,Canada.
Jodie I
JI
Roberts
2Department of Community Health Sciences,University of Calgary,Calgary,Alberta,Canada.
Colleen J
CJ
Maxwell
1Department of Clinical Neurosciences,University of Calgary,Calgary,Alberta,Canada.
Eric E
EE
Smith
7Department of Medicine (Neurology),Sunnybrook Health Sciences Centre,University of Toronto,Toronto,Ontario,Canada.
Sandra E
SE
Black
1Department of Clinical Neurosciences,University of Calgary,Calgary,Alberta,Canada.
Laura
L
Blaikie
8Department of Medicine,Cumming School of Medicine,Brenda Stafford Chair in Geriatric Medicine,University of Calgary,Calgary,Alberta,Canada.
Adrienne
A
Cohen
1Department of Clinical Neurosciences,University of Calgary,Calgary,Alberta,Canada.
Lundy
L
Day
2Department of Community Health Sciences,University of Calgary,Calgary,Alberta,Canada.
Jayna
J
Holroyd-Leduc
9Department of Medicine,University of Saskatchewan,Saskatoon,Saskatchewan,Canada.
Andrew
A
Kirk
1Department of Clinical Neurosciences,University of Calgary,Calgary,Alberta,Canada.
Dawn
D
Pearson
1Department of Clinical Neurosciences,University of Calgary,Calgary,Alberta,Canada.
Tamara
T
Pringsheim
1Department of Clinical Neurosciences,University of Calgary,Calgary,Alberta,Canada.
Andres
A
Venegas-Torres
3Hotchkiss Brain Institute,University of Calgary,Calgary,Alberta,Canada.
David B
DB
Hogan
D000367:Age Factors; D016206:Databases, Bibliographic / Q000706:statistics & numerical data; D003704:Dementia / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D015995:Prevalence
dementia; meta-analysis; systematic review