Apathy — a lack of interest or motivation — observed in patients could help doctors to predict the onset of some dementia forms years before the symptoms begin.
Very early signs of dementia
Led by Professor James Rowe at the University of Cambridge, a team of scientists highlighted apathy as a symptom of frontotemporal dementia that presents itself years before other behavioral symptoms — such as impulsivity and repetitive compulsive behavior.
Frontotemporal dementia is often diagnosed between the ages of 45 and 65. It is caused by a shrinkage in special parts at the front of the brain. A common feature of frontotemporal dementia is apathy.
The problem is that this sudden onset of apathy is often misdiagnosed as depression, as it can begin decades before other symptoms.
"Apathy is one of the most common symptoms in patients with frontotemporal dementia. It is linked to functional decline, decreased quality of life, loss of independence, and poorer survival," Maura Malpetti, a cognitive scientist at the Department of Clinical Neurosciences, University of Cambridge, explained in a press release.
"The more we discover about the earliest effects of frontotemporal dementia, when people still feel well in themselves, the better we can treat symptoms and delay or even prevent the dementia," she continued.
The new discovery comes thanks to the Genetic Frontotemporal dementia Initiative (GENFI), a collaboration between scientists across Europe and Canada.
Over 1,000 people, selected from families where there is a genetic cause of frontotemporal dementia, are taking part in GENFI.
Subtle changes revealed through observation
The University of Cambridge study involved the observation of 304 healthy people carrying a faulty gene that causes frontotemporal dementia and 296 of their relatives who have normal genes.
None of the participants had dementia, and most people taking part in the study did not know whether they carried a dementia-prone gene or not. The researchers looked out specifically for changes in apathy, as well as changes observed in memory tests and MRI scans of the brain.
"By studying people over time, rather than just taking a snapshot, we revealed how even subtle changes in apathy predicted a change in cognition, but not the other way around," explained Malpetti, the study's first author.
"We also saw local brain shrinkage in areas that support motivation and initiative, many years before the expected onset of symptoms."
The observations showed that people with genetic mutations had more apathy than other members of their family. What's more, the apathy predicted cognitive decline, which accelerated as the participants approached the estimated age of onset of symptoms.
Professor Rowe said the study highlights the importance of investigating why someone is feeling apathetic: "There are many reasons why someone feels apathetic. It may well be an easy to treat medical condition, such as low levels of thyroid hormone, or a psychiatric illness such as depression."
"But doctors need to keep in mind the possibility of apathy heralding a dementia, and increasing the chance of dementia if left unaddressed, particularly if someone has a family history of dementia," he continued.
"Treating dementia is a challenge, but the sooner we can diagnose the disease, the greater our window of opportunity to try and intervene and slow or stop its progress."
The researchers say that their new findings could herald a new method for testing patients showing early signs of dementia. As well as bolstering new treatments for the disease, it could potentially prevent the unfortunate misdiagnosis of many patients worldwide.