Alzheimer disease

Alzheimer or Dementia: Noninvasive Test May Help Differentiate

Transcranial magnetic stimulation (TMS) could be used to differentiate patients with Alzheimer disease (AD) from those with frontotemporal dementia (FTD), according to the findings of a recent study.

The study included a total of 175 participants, of whom 79 were diagnosed with AD, 64 were diagnosed with FTD, and 32 were healthy controls. All participants underwent paired-pulse TMS, which was used to measure the activity of different intracortical circuits. The sensitivity and specificity of TMS measures were assessed as the primary outcomes.
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The researchers found that patients with AD had a specific impairment of short-latency afferent inhibition, and that FTD was associated with a “remarkable dysfunction” of short-interval intracortical inhibition and facilitation intracortical circuits.

Overall, TMS differentiated FTD and AD with a sensitivity of 91.8% and specificity of 88.6%, and differentiated AD from health controls with a sensitivity of 84.8% and specificity of 90.6%. TMS differentiated FTD from health controls with a sensitivity of 90.2% and specificity of 78.1%. These results were confirmed in patients with mild forms of AD and FTD.

“TMS is a noninvasive procedure that reliably distinguishes AD from FTD and [healthy controls] and, if these findings are replicated in larger studies, could represent a useful additional diagnostic tool for clinical practice,” the researchers concluded.”

—Melissa Weiss

Reference:

Benussi A, Di Lorenzo F, Dell’Era V, et al. Transcranial magnetic stimulation distinguishes Alzheimer disease from frontotemporal dementia [published online before print July 26, 2017]. Neurology.  http:/​/​dx.​doi.​org/​10.​1212/​WNL.​0000000000004232.