Though the brain is known to shrink with age, people who show evidence of apathy and declining interest and emotion as they get older could be signaling decreased brain volume, according to a new study.
Past research has linked late-life depression and hearing loss to brain shrinkage, and a study published Wednesday in the online issue of Neurology, suggests that symptoms of apathy, without depression, could also be an indicator of brain disease.
The study measured two parts of the brain — gray matter associated with learning and storing memories and white matter, which is basically the communication center connecting the different areas of the brain. Using brain volume, or brain size, as a measure of brain aging, researchers gave MRIs to 4,354 people in their mid-70s and asked questions to measure indications of apathy, which can include lack of interest, lack of emotion, social withdrawal, lack of energy and a preference to stay home.
In the study, people with two or more symptoms of apathy had 1.4% smaller gray matter volume and 1.6% less white matter than those with less than two symptoms of apathy. That's equivalent to what two or three years of aging would look like in an average cognitively stable older person, according to an e-mail statement from Lenore J. Launer, a researcher on the study with the National Institute of Aging.
Apathy, which has similar symptoms to depression, is hard to measure because the symptoms are more subtle and complex, according to Ronald Petersen, the director of the Mayo Alzheimer's Disease Research Center at the Mayo Clinic in Rochester, Minn., who is not associated with the study.
"Someone with apathy probably won't go into the doctor's office and say 'I'm feeling apathetic,' " Petersen said. "These are people who are feeling less involved and might not be as willing to seek help."
Launer's statement suggests apathy may be an indicator of other underlying disease patterns that might be preventable or at least reduced.
Though there is no real way to combat decreased brain volume as people age, Petersen says studies have shown exercise can slow down the effects of brain volume loss. He says the study reinforces the need to be aware of symptoms as people age.
The study notes that researchers are not sure whether apathy is a precursor to brain shrinkage or if brain shrinkage leads to apathy.
"The study doesn't show the cause and effect of apathy — it could be that in some people, it signals a pending developing generative disease or cognitive impairment or even early signs of depression," Petersen says. "It could be any number of things, so the message is don't ignore symptoms."
The study was supported by the National Institutes of Health, the National Institute on Aging, the Icelandic Heart Association and the Icelandic Parliament.