Older individuals who have apathy - a lack of interest or emotion - are more likely to have smaller brain volumes than people who are not apathetic, according to new research published in the journal Neurology.
The research team, including Lenore J. Launer, PhD, of the National Institute on Aging at the National Institutes of Health (NIH) in Bethesda, MD, says that past research has indicated a relationship between depression later in life and white matter lesions (WML) - small areas of dead cells - on the brain.
In individuals with cognitive impairment and Alzheimer's disease, apathy has been associated with increased WMLs in the frontal lobe of the brain, as well as atrophy - a reduction in brain size.
This prompted the researchers to wonder whether apathy contributes to such brain changes in people without dementia or depression.
"It remains unclear whether apathy is related to atrophy and WMLs in older persons without dementia," the study authors write.
"Because apathy differs in prognosis and pharmacologic treatment and can occur independent of depression, it is important to distinguish apathy from late-life depression."
For their study, the team analyzed 4,354 people without dementia who were an average age of 76 years.
Older individuals who have apathy - a lack of interest or emotion - may have smaller brain volume than those without apathy.
All patients underwent magnetic resonance imaging (MRI) and were required to answer a questionnaire that measured apathy - the 15-item Geriatric Depression Scale (GDS-15).
The questions looked at their lack of interest, lack of emotion, lack of energy, whether they preferred to stay at home and their overall activities and interests.
Apathy alone 'could indicate brain disease'
The investigators found that individuals who had two or more symptoms of apathy had 1.4% less gray matter volume and 1.6% less white matter volume than those who had fewer than two apathy symptoms.
The gray matter regions of the brain are where memories are stored and where learning takes place, while white matter is responsible for communication between different brain regions. Therefore, loss of such matter can have implications for cognitive functions.
When the researchers accounted for individuals who had depression, they found the results remained the same, suggesting that apathy alone may be a risk factor for loss of white and gray matter.
Commenting on the findings, Launer says:
"Just as signs of memory loss may signal brain changes related to brain disease, apathy may indicate underlying changes.
Apathy symptoms are common in older people without dementia. And the fact that participants in our study had apathy without depression should turn our attention to how apathy alone could indicate brain disease."
The researchers note that standard tools to measure depression do not recognize signs of apathy, which is a concern, considering that many older people have such feelings.
Launer points out that if the team's findings are confirmed, developing strategies to identify apathy earlier may be a way of targeting individuals who are at risk of brain disease.
But the researchers say there are some limitations to their study. For example, they note they did not use a formal diagnosis of apathy when assessing participants.
"However," they add, "the GDS-15 apathy subscale has been shown to have a consistent correlation with a formal diagnosis of apathy and has been used as a measure of apathy in other large population-based studies."
Earlier this year, Medical News Today reported on a study from Johns Hopkins University in Baltimore, MD, suggesting that hearing loss in older adults may be linked to faster brain shrinkage.