Motor neuron disease group accompanied by inclusions of unidentified protein signaled by ubiquitin.

Peculiar tau-negative, ubiquitin-positive inclusions appear in dementia with ALS (ALS-D), the majority of lobar atrophy (Pick's disease) without Pick body and a small portion of ALS. Another common neuropathological lesion in these diseases is the motor neuron involvement with the degenerative processes. The lower motor neuron is predominantly involved in ALS and ALS-D the upper motor neuron is predominantly involved, but in varying degrees in a considerable number of patients with lobar atrophy that lack Pick bodies. There are, however, some points that have yet to be elucidated. The boundary between these diseases is not always clear and a significant number of cases are considered to be the transitional form. Lobar atrophy without Pick body seems to be a heterogeneous disease group. The nature of ubiquitin inclusions also needs to be clarified. Nevertheless, we postulate that these diseases are grouped with the concept of motor neuron disease-inclusion dementia.