As the World's population ages, the number of people experiencing cognitive decline and dementia will continue to increase. Currently available estimates suggest that over 24 million people worldwide had dementia in 2005, with this number expected to reach 50 million by 2025 
. The direct and indirect costs associated with dementia will also continue to rise, and conditions such as Alzheimer's disease are expected to become leading causes of health expenditure in developed and developing countries 
. Such considerations have stimulated the search for factors that might delay or prevent the progression of cognitive decline in older adults at risk, with promising results being reported for physical activity 
, adequate management of diabetes and hypertension 
, and participation in cognitively stimulating activities 
. Data from the Bronx Aging Study showed that the hazard of dementia over 5 years was decreased amongst older adults involved in cognitively stimulating activities, with the lowest risk observed for the most active participants 
. A subsequent randomized trial of cognitive training for adults aged 65–94 years (ACTIVE trial) found that the 10-week intervention was associated with specific cognitive gains over 2 years 
, whereas reasoning training led to less pronounced decline in self-reported instrumental activities of daily living over 5 years 
. Although the ACTIVE trial was unable to establish if the intervention decreased the onset of dementia amongst participants, its results are consistent with the hypothesis that regular involvement in mentally demanding activities improves function and may reduce the risk of dementia.
In this context, the increasing ease of access to personal computers that has occurred over the past 20 years offers hope that the growing exposure of older adults to this technology will enhance their participation in mentally stimulating activities and contribute to maintain cognitive function and reduce the prevalence of dementia in the community. In Australia, 47% of the population over the age of 60 years used computers in 2009, compared with only 29% in 2003 
. In Western Australia, 66% of older adults reported having a computer at home in 2009, and 58% had access to the internet 
. Over 80% of those with access to the internet used email and chat sites or conducted general browsing. About 50% used the internet to pay bills, manage their finances or to access government services. Over 1/3 purchased goods and about 10% used the internet to manage their shares 
. However, the health effects of computer use and internet access remains uncertain.
As the use of computers has previously been associated with improved cognitive function in adulthood and old age 
and participation in cognitively stimulating activities reduces the long-term risk of dementia 
, we hypothesized that older computer users would have lower risk of developing dementia than non-users over a follow up period of up to 8 years. We conducted this study to test this hypothesis.