Grandparents is not a synonym for elderly

This headline appeared in the Dominion Post, 19 October 2009:
Surfing's good for grandparents.

First sentence:

Internet use can boost the brain activity of the elderly, potentially slowing or even reversing the age-related declines that can end in dementia, researchers found.

The study was by Gary Small, professor of neuroscience and human behaviour at UCLA,and his colleagues. The results are fascinating, but they have nothing to do with grandparents. Possibly some of the 24 people studied were grandparents, as they were aged between 55 and 78. Possibly not.

The journalist, I'm guessing, was not of grandparenting age. Otherwise he or she would have noticed that:

• not everyone over 55 is a grandparent
• variables among subjects concerned age and internet use, not grandparenting
• the scientists used the terms older people and older adults, not grandparents.

First-time internet users find boost in brain function after just one week
P.S. Tim Jones points out that not all people over 55 are grandparents, either. A friend of his was a grandmother at 34.