The day is being co-ordinated by London-based umbrella organisation Alzheimer's Disease International (ADI), which is calling for countries' health ministers to give greater priority to the care offered to dementia sufferers.
Events are planned in countries from Argentina and Armenia to Venezuela and Zimbabwe.
ADI provides country organisations with advice on how to bag coverage and offers them a press release template.
World Alzheimer's Day launched 11 years ago with the support of the World Health Organisation. It was used to raise global awareness of dementia and the activities of Alzheimer's associations.
Last year the ADI used the day to point out that the number of people across the world with dementia is set to nearly double in the next 20 years.
The Alzheimer's Society, which held its own awareness week across England and Wales in July, is holding 'memory walks' across the country.
Next year is likely to see deeper collaboration and a larger PR campaign as 2006 marks 100 years since Alois Alzheimer first described the disease.
The ADI does not receive backing specifically for World Alzheimer's Day from pharmaceutical companies, it said.