Loss of memory and other brain function can start as early as age 45, posing a big challenge to scientists looking for new ways to keep off dementia (痴呆症), researchers said Thursday.
The finding from a 10-year study of more than 7,000 British government workers contradicts previous notions that cognitive decline does not begin before 60 years of age, and it could have far-reaching implications for dementia research.
Making sure the age at which memory, reasoning and comprehension skills start to worsen is important because drugs are most likely to work if given when people first start to experience mental damage.
A handful of novel medicines for Alzheimer's disease, the most common form of dementia, are currently in clinical trials, but expectations are low and some experts fear the new drugs are being tested in patients who may be too old to show a benefit.
The research team led by Archana Singh-Manoux from the Center for Research in Epidemiology and Population Health in France and University College London found a modest decline in mental reasoning in men and women aged 45-49 years.
"We were expecting to see no decline, based on past research," Singh-Manoux said in a telephone interview.
Among older subjects in the study, the average decline in cognitive function was greater, and there was a wide variation at all ages, with a third of individuals aged 45-70 showing no degradation over the period.
"It doesn't suddenly happen when you get old. That variability exists much earlier on," Singh-Manoux said. "The next step is going to tease that apart and look for links to risk factors."
Participants were assessed three times during the study, using tests for memory, vocabulary, and aural and visual comprehension skills.
Over the 10-year period, there was a 3.6 percent decline in mental reasoning in both men and women aged 45-49 at the start of the study, while the decline for men aged 65-70 was 9.6 percent and 7.4 percent for women.
Since the youngest individuals at the start of the study were 45, it is possible that the decline in cognition might have commenced even earlier.
Singh-Manoux said the results may also have underestimated the cognitive decline in the broader population, since the office workers in the study enjoyed a relatively privileged and healthy lifestyle.
Factors affecting vascular (心血管的) function such as obesity, high blood pressure, highcholesterol (胆固醇) and smoking—are believed to impact the development of Alzheimer's andvascular (心血管的) dementia through effects on brain blood vessels and brain cells.
Most research into dementia has focused on people aged 65 and over. In future, scientists will need to devise long-term clinical studies that include much younger age groups and may have to enroll tens of thousands of participants, she said.
6. People used to think that loss of memory and other brain function _______.
A) can start at the age of 45
B) do not start before age 60
C) are symbols of dementia
D) pose a big challenge to scientists
7. Why is it important to make sure when people's cognitive skills begin to decline?
A) It can help scientists find out the causes of dementia.
B) It is a breakthrough to keep off dementia.
C) The treatment may have better effects.
D) People can take precaution measures before that age.
8. What does the study reveal?
A) There is no variation of cognitive decline at all ages.
B) Cognitive decline is likely to occur earlier than age 45.
C) British government workers are especially vulnerable to dementia.
D) Cognitive decline suddenly happens if people don't do exercises.
9. Singh-Manoux would agree that _______.
A) the tests for memory, vocabulary and comprehension skills are incomplete.
B) there is no decline in mental reasoning based on previous researches.
C) the results of the study may exaggerate the cognitive decline.
D) the objects' lifestyle may influence the results of cognitive decline.
10. What should the scientists do in order to get more accurate results in future studies?
A) Cover much younger age groups and more participants.
B) Attach more importance to people aged 65 and above.
C) Apply various comprehension skills in more tests.
D) Get younger patients to test the new drugs.
Keys: 6-10 BCBDA