Revised criteria improve early-onset dementia diagnosis

Apr 29 2013

By Peter Sergo, medwireNews Reporter

Updated diagnostic criteria based on the Frontotemporal Dementia Consensus (FTDC) are "encouragingly" sensitive and specific in identifying patients who have early-onset dementia, a study finds.

"The [revised] FTDC criteria… are effective in distinguishing between FTLD [frontotemporal lobar degeneration] and other pathologies during life," explain Matthew Jones (University of Manchester, UK) and co-authors in Neurology.

The study involved a total of 156 patients who predominantly had autopsy-confirmed dementia that was predominantly early-onset , with symptom onset before the age of 65 years.

The updated criteria had a sensitivity of 95% and specificity of 82% when used to rate patients (n=146) for possible behavioral variant frontotemporal dementia (bvFTD) - the second most common form of dementia affecting younger people.

The same assessment had a sensitivity of 85% and specificity of 95% for rating patients for probable bvFTD (n=138).

"Unsurprisingly, there was a tradeoff between sensitivity and specificity for 'possible' and 'probable' bvFTD," the authors comment. "When the more stringent criteria for probable bvFTD were applied, specificity increased but at the expense of sensitivity."

Specifically, "loss of sympathy and empathy" proved to have the highest specificity while "executive/generation deficits with relative sparing of memory and visuospatial functions" had the highest sensitivity.

Although three patients had FTLD pathology they still did not fulfill the criteria for possible bvFTD (false-negative cases). Conversely, 15 patients met the criteria for possible bvFTD but had other pathologies (false-positive cases), which were predominantly presenile Alzheimer's disease.

"This finding exemplifies the point that criteria provide a valuable adjunct to but are not a substitute for clinical experience," the authors write.

"Although frontotemporal changes on neuroimaging increase specificity of diagnosis of FTD, they may not invariably be present in early-stage disease," the research team adds.

The authors say that their findings, in a patient cohort representing a range of FTLD pathologies, also confirm the sensitivity of the updated criteria to bvFTD that is associated with tau, transactive response DNA binding protein 43, and fused in sarcoma pathologies.

Notably, executive deficits were more prominent than other cognitive deficits and proved to be a highly sensitive behavioral feature in bvFTD, which the authors say reflects the importance of neuropsychologic assessment when evaluating patients with FTD.

Altogether, conclude the authors, the revised diagnostic criteria "provide a useful tool both for specialist researchers and general clinicians."

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