New York: Facing smell loss may be an important early sign marking older adults at higher risk of cognitive decline which leads to dementia, a finding that may help develop new treatments and preventative interventions for the neuro degenerative disease, researchers say.
"Loss of the sense of smell is a strong signal that something has gone wrong and significant damage has been done," said lead author Jayant M. Pinto, Professor at the University of Chicago.
For the study, published in the Journal of the American Geriatrics Society, the team conducted a long-term study of nearly 3,000 adults, aged 57 to 85.
The results showed that participants who could not identify at least four out of five common odours were more than twice as likely as those with a normal sense of smell to develop dementia within five years.
Nearly 80 per cent of those who provided only one or two correct answers also had dementia, with a dose-dependent relationship between degree of smell loss and incidence of dementia.
"These results show that the sense of smell is closely connected with brain function and health," Pinto said.
The olfactory system or sense of smell also has stem cells which self regenerate. Thus, "a decrease in the ability to smell may signal a decrease in the brain's ability to rebuild key components that are declining with age, leading to the pathological changes of many different dementias", noted co-author Martha K. McClintock, Professor at the varsity.
Losing the ability to smell can have a substantial impact on lifestyle and well-being, as smells influence nutrition and mental health.
"Being unable to smell is closely associated with depression as people don't get as much pleasure in life," Pinto said.