Reader Response: Phenotypic Variability in ALS-FTD and Effect on Survival

I read the article by Ahmed et al.1 and generally agree with their comments. However, I offer some insights. First, Yuasa2 reported a case of amyotrophic lateral sclerosis (ALS) with dementia who presented impairment of personality, forgetfulness, and forced grasp before presenting muscle weakness. The patient showed brain atrophy in the frontal lobe. Following reports—including autopsies and neuroimages that supported ALS with dementia or motor neuron disease (MND) with dementia—showed atrophy, reduced blood flow, or hypometabolism characterized demonstrated in the central region and in the frontal lobe. The authors suggested that emotion processing and behavior disturbance had been considered core deficits in behavioral variant frontotemporal dementia (bvFTD) and believed to be less prominent in ALS-FTD. However, other studies including Yuasa’s suggested behavioral changes in patients with ALS-FTD in their early stages. To elucidate these differences, the morphological study does not have enough power, but functional imaging studies may hold advantages.3 We studied patients with ALS with dementia by using SPECT and concluded ALS and ALS with dementia made a wide spectrum of a disease.4 The authors’ indication of atrophy in the dorsolateral prefrontal cortex (DLPFC) might be a key for differential diagnoses of variant types of ALS-FTD. I recently had a patient with ALS-FTD who showed dominant bulbar palsy with forgetfulness but preserved personality. His SPECT showed reduced uptake in the central and prefrontal cortex not in the DLPFC. I agree that further studies of ALS, ALS-FTD, and bvFTD are needed, but I suggest that function studies should be included in future projects.

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