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:

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  • Daily Chores And Exercise

    A recent study in the <a href="http://www.neurology.org/content/early/2012/04/18/WNL.0b013e3182535f0e.extract" target="_hplink">journal <em>Neurology</em></a> showed that simple activities like <a href="http://www.huffingtonpost.com/2012/04/20/chores-alzheimers-exercise-_n_1440969.html" target="_hplink">cooking, cleaning and washing the dishes</a> -- as well as good, old-fashioned exercise -- is associated with a decreased Alzheimer's disease risk, even among people who are age 80 and older. <br> <br> Researchers found that the people who were the least active each day -- in the bottom 10th percentile in the study -- were two times more likely to go on to develop Alzheimer's disease, compared with people who were in the top 10th percentile for daily activity. <br> <br> The results were even more marked when evaluating the intensity of physical activity: Those who were in the bottom 10th percentile for physical activity intensity were three times more likely to develop Alzheimer's, compared with those in the top 10th percentile.

  • Speak Two Languages

    Being bilingual could strengthen your brainpower and protect against dementia, according to a recent study published in the <a href="http://www.cell.com/trends/cognitive-sciences/" target="_hplink">journal <em>Trends in Cognitive Sciences</em></a>. <br> <br> HuffPost Canada Living <a href="http://www.huffingtonpost.ca/2012/04/02/benefits-of-being-bilingual_n_1396671.html" target="_hplink">explains why</a>: <br> <br> <blockquote>The anticipation of having to speak one of two language at any given time forces the brain to run continually, and results in an experience that helps avoid a mental conflict between languages.</blockquote> <br> <br> "It is rather like a reserve tank in a car. When you run out of fuel, you can keep going for longer because there is a bit more in the safety tank," study researcher Dr. Ellen Bialystok <a href="http://www.guardian.co.uk/science/2011/feb/18/bilingual-alzheimers-brain-power-multitasking" target="_hplink">told <em>The Guardian</em></a>.

  • Consume Curcumin

    Research in flies suggests that the main compound in turmeric, called curcumin, could have powers against Alzheimer's. <br> <br> <em>The Telegraph</em> reported on a study in the journal <em>PLoS ONE</em>, which suggested that <a href="http://www.telegraph.co.uk/health/healthnews/9084973/Having-a-curry-could-help-ward-off-dementia.html" target="_hplink">curcumin may work</a> by reducing the amount of oligomers, which are the "precursor" forms of amyloid plaques in the brain. <br> <br> A previous study in the journal <em>Annals of Indian Academy of Neurology</em> discussed the possible <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781139/" target="_hplink">effects of curcumin on Alzheimer's</a>. Researchers wrote: <br> <br> <blockquote>Due to various effects of curcumin, such as decreased Beta-amyloid plaques, delayed degradation of neurons, metal-chelation, anti-inflammatory, antioxidant and decreased microglia formation, the overall memory in patients with AD has improved.</blockquote>

  • Do Puzzles

    <a href="http://www.huffingtonpost.co.uk/2011/12/01/puzzles-and-exercise-help-beat-dementia-symptoms_n_1122502.html" target="_hplink">Doing some puzzles</a> and playing games every day could ward off mental decline, according to a recent study in the journal <em>BMC Medicine</em>. <br> <br> Researchers from the University of Erlangen conducted a study in dementia patients in nursing homes, and had the study participants do exercises like bowling and solving puzzles together, the Press Association reported. They also spent some time doing things like woodwork and gardening. <br> <br> The researchers found that all of these activities seemed to have the same effect on the study participants' <a href="http://www.huffingtonpost.co.uk/2011/12/01/puzzles-and-exercise-help-beat-dementia-symptoms_n_1122502.html" target="_hplink">brain functioning</a>, compared with the typical dementia medication, the Press Association reported. <br> <br> Another recent study in the journal <em>Archives of Neurology</em> showed that life-long reading and game-playing could <a href="http://www.medicinenet.com/script/main/art.asp?articlekey=153901" target="_hplink">decrease beta amyloid levels</a> in the brain, which are considered a "hallmark of the condition," MedicineNet reported. <br> <br> "Staying cognitively active over the lifetime may reduce the risk of Alzheimer's by preventing the accumulation of Alzheimer's-related pathology," study researcher Susan Landau, a research scientist at the Helen Wills Neuroscience Institute at the University of California, Berkeley, <a href="http://www.medicinenet.com/script/main/art.asp?articlekey=153901" target="_hplink">told MedicineNet</a>.

  • Walk!

    Elderly people who <a href="http://www.bbc.co.uk/news/health-11537068" target="_hplink">walk six to nine miles a week</a> could decrease their risk of dementia and brain functioning problems, BBC News reported. <br> <br> The 2009 study in <em>Neurology</em> included 299 people whose average age was 78. Researchers found that people who walked the most in the study -- six to nine miles a week -- had a halved risk of developing the brain problems as people who walked the least in the study, according to BBC News. <br> <br> Similarly, a 2007 study that also appeared in the journal <em>Neurology</em> showed that people age 65 and older who regularly exercise have a <a href="http://www.eurekalert.org/pub_releases/2007-12/aaon-wam121107.php" target="_hplink">decreased risk of vascular dementia</a>. That study included 749 people.

  • Eat Your Fish And Nuts

    Researchers from Columbia University Medical Center found that eating a <a href="http://www.huffingtonpost.com/2012/05/06/omega-3-fatty-acids-alzheimers-memory-brain_n_1475806.html" target="_hplink">diet high in omega-3 fatty acids</a> -- such as fish, nuts and chicken -- is linked with lower levels of of beta-amyloid protein, which is linked with Alzheimer's disease. <br> <br> The study, published in the journal Neurology, included 1,219 people age 65 and older who didn't have dementia. The researchers found that the higher their consumption of the omega-3 fatty acids, the lower the beta-amyloid in the blood.

  • Drink Green Tea

    That refreshing green brew could have powers against Alzheimer's disease, according to research from Newcastle University. <br> <br> WebMD reported that when <a href="http://www.webmd.com/alzheimers/news/20110106/green-tea-may-help-prevent-alzheimers-disease" target="_hplink">green tea is digested</a>, the released compounds have protective effects against Alzheimer's. <br> <br> "When green tea is digested by enzymes in the gut, the resulting chemicals are actually more effective against key triggers of Alzheimer's development than the undigested form of the tea," study researcher Ed Okello <a href="http://www.guardian.co.uk/society/2011/jan/06/green-tea-alzheimers-cancer" target="_hplink">told <em>The Guardian</em></a>.

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