The University of Tasmania's free online course Understanding Dementia has been named one of the top 50 online courses of all time.

It was also rated most popular in the health and medical category in the list compiled by massive open online course (MOOC) aggregator Class Central.

The nine-week course has attracted more than 70,000 people from 170 countries since it began in 2013 and was developed by the University’s Wicking Dementia Research and Education Centre.

Co-director James Vickers (pictured) said the course had a completion rate of 38 per cent, which is very high for a free online course.

He credits its popularity to providing a forum for people to discuss issues related to dementia with others involved in treating it or dealing with it in their own families.

The Centre has now launched a second online course called Preventing Dementia, which drew 11,000 participants to its first intake and will run again in 2017.