Key points from article :
Being socially active in 50s and 60s protects against dementia risk in later life.
Using the brain for memory and language during social contact can build cognitive reserve.
This research involved more than 10,000 participants from 1985 to 2013.
Needs community level and policy level work to make it easier for older people to stay socially active.
Study by University College London in UK, published in the journal PLOS Medicine.
