According to research published in The Journal of Prevention of Alzheimer's Disease, confusion over cash could be linked to the level of protein deposits built up in the brain.
Interestingly, these changes can happen even in adults who are cognitively healthy.
The findings were based on 243 adults aged between 55 to 99 who were tested on their financial skills. Brain scans were also given to help identify protein build-up of beta-amyloid plaques.
The study also included adults with mild memory impairment and people diagnosed with Alzheimer's - a form of dementia.
“There has been a misperception that financial difficulty may occur only in the late stages of dementia, but this can happen early and the changes can be subtle,” study senior author Professor Murali Doraiswamy, of Duke University in the US, said.
“The more we can understand adults' financial decision-making capacity and how that may change with ageing, the better we can inform society about those issues.”
READ MORE: What are the risk factors for dementia?
Tests revealed that financial skills decline with age and at the earliest stages of mild memory impairment - a drop similar in both men and women.
After taking into consideration the individual’s education and other demographics, the research team discovered that the more extensive the amyloid plaques were, the worse the person's ability to understand and apply basic financial concepts.
Although it is likely for cognitively healthy people to develop protein plaques as they age, they may appear more prematurely in those at risk of Alzheimer's due to family history of the illness or memory impairment.
But more testing for early dementia is needed, according to the research team.
A financial capacity assessment for instance, like the one used in this study, could be a tool used by doctors to help track a person’s cognitive function over time.
“Doctors could consider proactively counselling their patients using this scale, but it's not widely in use,” lead author Sierra Tolbert, said. “If someone's scores are declining, that could be a warning sign.”
There are over 850,000 people living with dementia in the UK with numbers set to rise to over one million by 2025.
An estimated 225,000 people will develop dementia this year, the equivalent of one every three minutes.
Symptoms of dementia can include memory loss, depression, anxiety, hallucinations and changes in behaviour.
For further information, help and support please visit the Alzheimer’s Society website.