05/25/2012 12:29 pm ET

Dementia In 'Middle-Income' Countries May Be Higher Than Thought; Linked With Education Levels

Dementia in "middle-income" countries like Cuba, Mexico and China may be higher than previously thought, and as suggested in other studies, the risk seems linked with education level, a new study suggests.

The research is published in the journal The Lancet, and was conducted by experts at the King's College London's Institute of Psychiatry.

The study included 12,800 people ages 65 and up, who had both the DSM-IV dementia criteria and the 10/66 Dementia Diagnosis applied to them. The researchers aimed to see how certain factors affected their dementia risk, including education levels and literacy. The study participants lived in Cuba, Venezuela, Peru, the Dominican Republic, Mexico and China.

Using a different dementia diagnosis approach -- called the 10/66 Dementia Diagnosis -- the levels of dementia may actually be 1.5 to 2.5 times higher than if using just the Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV, researchers found.

In addition, researchers found that low education, older age and being female were independent factors linked with dementia in the study. People with dementia in the study also had a tripled risk of death.

"Our results provide supportive evidence for the cognitive reserve hypothesis, showing that in middle-income countries as in high-income countries, education, literacy, verbal fluency, and motor sequencing confer substantial protection against the onset of dementia," researchers wrote in the study.

Dementia around the world is increasing -- in 2010, there were 35.6 million people with dementia, but there are estimated to be 115.4 million people in 2050 with the condition, according to Alzheimer's Disease International.

Alzheimer's Disease International explains the possible reason for this expected increase:

Many are now living longer and healthier lives and so the world population has a greater proportion of older people. Dementia mainly affects older people, although there is a growing awareness of cases that start before the age of 65.

For more on the research on Alzheimer's disease prevention, click through the slideshow below:

Habits That Could Lower Alzheimer's Risk