Pre-Dementia Linked to Ill Health
A large new study is highlighting a link between mild cognitive impairment, physical disability and psychological symptoms such as anxiety.
As populations in low and middle-income countries are aging, rates of dementia are rising, say Dr. Robert Stewart of King’s College London, UK, and colleagues in the journal PLoS Medicine. Currently, more than 35 million people worldwide have dementia, the majority of which is Alzheimer’s disease. More than 115 million people may have dementia by the year 2050, with much of this rise occurring in low- and middle-income countries.
“Mild cognitive impairment is a construct frequently used to define groups of people who may be at risk of developing dementia,” explain Dr. Stewart and colleagues. “It can be seen as an intermediate state between normal cognitive aging and dementia.”
People with mild cognitive impairment have problems that are more severe than those normally seen in people of a similar age, such as misplacing things and forgetting appointments, but they have no other symptoms of dementia and are able to look after themselves. The condition is currently defined as “a syndrome with impairment of memory or another cognitive deficit that does not interfere substantially with personal affairs nor result in inability to live independently.”
Knowing a country’s rates of mild cognitive impairment is crucial for helping governments plan their future health care and social support needs, but the rates in low- and middle-income countries are largely unknown.
The research team analyzed survey findings on 15,376 people ages 65 years or older without dementia living in Cuba, Dominican Republic, Peru, Mexico, Venezuela, Puerto Rico, China, and India.
Mild cognitive impairment was associated with physical disability, anxiety, apathy, and irritability, but not depression. It was not linked to age or education. Men had a slightly higher rate of mild cognitive impairment than women. This finding contrasts with higher reported rates of dementia among women than to men, but could be explained by the exclusion of confirmed dementia cases. Experts from the Mayo Clinic, Rochester, Minn., say that women may move from normal cognition directly to dementia at a later age but more abruptly.
Rates of mild cognitive impairment varied more than five-fold between countries, from 0.8 percent in China to 4.3 percent in India, but the authors think this mainly reflect difference in the diagnostic tests used.