Clinical factors of frontotemporal dementia misdiagnosis

Almost 70% of suspected frontotemporal dementia patients — a notoriously difficult-to-diagnose disorder — ultimately did not have the condition, an Australian study aimed at identifying clinical factors contributing to misdiagnoses of behavioural variants of frontotemporal dementia by specialist physicians has revealed. One of the most common forms of dementia in people aged under 65, unlike Alzheimer’s, which is characterised by memory problems, it involves degeneration of the frontal and temporal lobes of the brain, affecting behaviour and personality.

Lead author Dr Joshua Flavell, a psychiatrist working with cognitive neurologist Professor Peter Nestor — at the Mater Hospital Memory and Cognitive Disorders Clinic and the University of Queensland’s Queensland Brain Institute — are among the researchers who analysed data from 100 patients suspected of having frontotemporal dementia who had been referred to the Mater clinic by specialist physicians like geriatricians, neurologists or psychiatrists.

Initial referral information was compared with the final clinical diagnoses to determine patterns in diagnostic accuracy. “Of the 100 patients, 34 were true-positive, and 66 were false-positive for frontotemporal dementia,” Flavell said. “We found that misinterpretation of brain scans, particularly nuclear imaging, led to 32 patients being incorrectly diagnosed.” Flavell added, “Likewise, cognitive testing such as tests of executive function also contributed to misdiagnoses in 20 patients.”

“Psychiatric history was regularly downplayed by both patients and informants, making it difficult for physicians to understand how to place particular weight on this part of the diagnostic puzzle,” Flavell said. “Misdiagnosis can result in patients receiving inappropriate treatments, potentially leading to unnecessary medications, delays in proper care, and increased emotional distress for families.”

The study highlights the need for careful interpretation of diagnostic tests in patients suspected of having the condition. “We found patients with prior psychiatric histories were more likely to be misdiagnosed,” Flavell added. “Misinterpretation of brain scans and cognitive testing, particularly formal neuropsychological testing, significantly contributed to inaccurate diagnoses.” Regarding the findings, Nestor said physicians should be cautious not to over-interpret neuroimaging and neuropsychology results.

Nestor also said that physicians should 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,” Nestor said.

Over-interpretation of neuroimaging and neuropsychological assessments was the most common reasons for misdiagnosis. “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,” Nestor said. “By raising awareness of these pitfalls in the diagnostic process, we feel that diagnostic accuracy for frontotemporal dementia can be improved.”

“The behavioural variant of frontotemporal dementia is a challenging diagnosis due to overlapping symptoms with psychiatric and other neurological conditions,” the researchers wrote in the study. “Accordingly, misdiagnosis is common.” The study, titled ‘Factors associated with true-positive and false-positive diagnoses of behavioural variant frontotemporal dementia in 100 consecutive referrals from specialist physicians’, was published open access this year in the European Journal of Neurology.

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