Reasons for misdiagnosis of frontotemporal dementia

Psychiatrist Dr Joshua Flavell working with cognitive neurologist Professor Peter Nestor at the Mater Hospital Memory and Cognitive Disorders clinic and UQ's Queensland Brain Institute, analysed data from 100 patients suspected of having frontotemporal dementia who had been referred by specialist physicians like neurologists, psychiatrists or geriatricians.

"Of the 100 patients, 34 were true-positive, and 66 were false-positive for frontotemporal dementia," Dr Flavell said.

"We found that misinterpretation of brain scans, particularly nuclear imaging, led to 32 patients being incorrectly diagnosed.

"Likewise cognitive testing, such as tests of executive function, also contributed to misdiagnoses in 20 patients."

The study compared the initial referral information with the final clinical diagnoses to determine patterns in diagnostic accuracy.

Frontotemporal dementia is one of the most common forms of dementia in people aged under 65.

Unlike Alzheimer's, which is characterised by memory problems, frontotemporal dementia involves degeneration of the frontal and temporal lobes of the brain, affecting personality and behaviour.

Dr Flavell said the study highlighted the need for careful interpretation of diagnostic tests in patients suspected of having the disease.

"We found patients with prior psychiatric histories were more likely to be misdiagnosed," he said.

"Misinterpretation of brain scans and cognitive testing, particularly formal neuropsychological testing, significantly contributed to inaccurate diagnoses."

Professor Nestor said physicians should be cautious not to over-interpret neuroimaging and neuropsychology results and be hesitant to label behavioural change as frontotemporal dementia in patients with prior psychiatric histories.

"More emphasis should be placed on directly observing behaviours associated with frontotemporal dementia and physical neurological signs in the clinic, rather than relying solely on second-hand reports of symptoms," he said.

"The team compared the initial referral diagnosis of suspected frontotemporal dementia to long-term outcome, following people for as long as five years to be confident of the diagnosis.

"By raising awareness of these pitfalls in the diagnostic process, we feel that diagnostic accuracy for frontotemporal dementia can be improved."

The research was published in the European Journal of Neurology.