Being socially active in your 50s and 60s may help lower the risk of developing dementia（痴呆）in later life，a study has found.
Researchers studied data that tracked more than 10,000 people from 1985 to 2013.The participants answered a questionnaire（调查问卷）every five years about the frequency of their social contact with friends and relatives.They were also subject to cognitive testing,and electronic health records were searched for dementia diagnoses.
The results published in the joumnal PLoS showed that seeing friends almost daily at age 60 was associated with a 12% lower likelihood of developing dementia in later life,compared with those who saw only one or two friends every few months.Seeing relatives, on the other hand,did not show the same beneficial association.
The authors suggest that practising using the brain for memory and language during social contact can build so-called cognitive reserve.
Tara Spires-Jones,a professor at the University of Edinburgh who was not involved in the work,explained:"Learning new things builds connections between brain cells,and so does social contact. The biology underlying this study is that the people who are socially active keep their brains better connected. If you have a better connected network in your brain, it can resist pathology（病状）for longer.＂
Clive Ballard, a professor of age-related disorders at the University of Exeter,who was also not involved in the work, said:"There are plenty of other studies that have foundthat social isolation is a risk factor. The strength of this work is the large population studied,and that the assessment of social contact was done so long before the cognitive assessment.It makes the direction of cause-and-effect much stronger."
The authors note that the data does not include detail on the quality of social contact,and that dementia cases may have been missed if participants did not present themselves to their doctors.
There may also be overlapping factors at play:“It is known that depression is a significant risk factor, and our work has shown that hearing loss is also a significant risk factor.Both of those might lead to social isolation. Ir's likely to be a cluster of things which are not totally independent,"said Ballard.
The work contributes to growing evidence that social activities could protect people from dementia in the long run, in addition to treating hearing loss and maintaining a healthy lifestyle.
Which of the following is missing from the data?
A、The number of participants.
B、The electronic health records.
C、The frequency of social contact.
D、The detail on the quality of social contact.
【正确答案】：D
