Amyotrophic lateral sclerosis with dementia: The clinicopathological spectrum

Amyotrophic lateral sclerosis with dementia (ALS‐D) is a non‐Alzheimer‐type dementia characterized by both frontotemporal degeneration and motor neuron disease and marked by ubiquitin‐positive, tau‐ and α‐synuclein‐negative intraneuronal inclusions and dystrophic neurites. New neuropathological diagnostic criteria for ALS‐D are proposed on the basis of the present investigation of 28 autopsy cases. Clinical features included those of typical ALS‐D, primary lateral sclerosis, atypical ALS with frontotemporal atrophy and atypical Pick's disease without Pick's bodies. Macroscopically anterior frontotemporal atrophy was observed involving or not involving the precentral gyrus. Microscopically non‐specific neuronal loss and gliosis with spongiosis were seen, particularly in superficial layers II and III of the frontotemporal cortices. Diffuse fibrous gliosis was seen in the frontotemporal white matter. The substantia nigra and amygdala showed neuronal loss and gliosis. In all 28 cases, degeneration of both the lower and upper motor neuron systems, consistent with classic sporadic ALS, was present. The distribution and degree of degenerative frontotemporal lesions and motor neuron disturbance were of various patterns. Ubiquitin‐positive and tau‐ and α‐synuclein negative intraneuronal inclusions and dystrophic neurites in extramotor cortices were observed in all cases. Furthermore, ubiquitin‐positive inclusions in lower motor neurons were found in all cases. The distribution pattern and density differed between neuronal inclusions and dystrophic neurites and correlated with clinicopathological phenotypes. Therefore, the ALS‐D spectrum may be broader than that previously recognized, extending to primary lateral sclerosis, atypical ALS and to atypical Pick's disease without Pick bodies. Further investigation is needed to determine the characteristics of the ubiquitinated component in ALS‐D.