International Psychogeriatrics

Research Article

Prevalence of very mild and mild dementia in community-dwelling older Chinese people in Hong Kong

Linda C. W. Lama1 c1, Cindy W. C. Tama1, Victor W. C. Luia1, W. C. Chana2, Sandra S. M. Chana1, Sunny Wonga1, Ada Wonga3, M. K. Thama3, K. S. Hoa3, W. M. Chana3 and Helen F. K. Chiua1

a1 Department of Psychiatry, The Chinese University of Hong Kong, New Territories, Hong Kong SAR, The People's Republic of China

a2 Castle Peak Hospital, Tuen Mum, Hong Kong SAR, The People's Republic of China

a3 Elderly Health Service, Department of Health, Hong Kong SAR, The People's Republic of China


Introduction: In this report, the results of a household survey were used to examine the prevalence of very mild and mild dementia in Chinese older persons in Hong Kong.

Methods: The study adopted a two-phase design. At Phase 1, 6100 subjects were screened using the Cantonese version of the Mini-mental State Examination (MMSE) and a short memory inventory. At Phase 2, 2073 subjects were screened positive and 737 were evaluated by psychiatrists. Clinical Dementia Rating (CDR) and cognitive assessment were used for diagnosis of dementia. Very mild dementia (VMD) was defined as a global CDR of 0.5, with memory and non-memory subscale scores of 0.5 or more. Mild dementia was classified for subjects with a CDR of 1.

Results: The overall prevalence of VMD and mild dementia for persons aged 70 years or above was 8.5% (95%CI: 7.4–9.6) and 8.9% (95%CI: 7.8–10.0) respectively. Among subjects with clinical dementia, 84.6% had mild (CDR1) dementia. Logistic regression analyses revealed that older age, lower educational level and significant cerebrovascular risk factors were risk factors for dementia, while regular physical exercise was a protective factor for dementia.

Conclusions: A sizable proportion of community-living subjects suffered from milder forms of dementia. They represent a high risk for early intervention to reduce potential physical and psychiatric morbidity.

(Received May 09 2007)

(Online publication June 12 2007)

(Revised June 28 2007)

(Accepted June 29 2007)

(Online publication September 25 2007)