A new study finds people who are apathetic, but not depressed when they're older may be developing dementia.

"This may be an early symptom for damage to the brain due to either diseases like Alzheimer's disease, or stroke, or perhaps both," said Cleveland Clinic Dementia expert Dr. James Leverenz.

Researchers with the National Institutes of Health studied nearly 4,400 people without dementia whose average age was 76. Participants underwent MRI scans and were asked questions that measure apathy symptoms, which include things like lack of interest, lack of emotion, and dropping activities.

Results show people with 2 or more apathy symptoms had smaller gray matter and white matter volumes in their brains. Gray matter is where learning takes place and memories are stored in the brain. White matter acts as the communication cables that connect different parts of the brain. Researchers say identifying apathy earlier may be a way to target people who may be at-risk of developing dementia. Leverenz agrees.

"I think it is something to pay attention to. If you start to notice someone who is normally very active and is now not getting out as much, not interested in activities as much, it's worth exploring," said Leverenz.