What is frontotemporal lobe dementia with motor neuron disease (FTD/MND)?

Updated: Apr 11, 2017
  • Author: Jasvinder Chawla, MD, MBA; Chief Editor: Jasvinder Chawla, MD, MBA  more...
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Patients with motor neuron disease (MND) are generally free of cognitive impairment, but evidence is growing to support an association between MND and frontal lobe or frontotemporal dementia (FTD).

MND, as the name suggests, is a pure motor disorder without any significant evidence of sensory symptoms, extraocular movement disturbances, bladder and bowel dysfunction, or cognitive impairment. Cognitive impairment in amyotrophic lateral sclerosis (ALS) is correlated with pathologic and radiographic changes in the cerebral cortex beyond the motor regions. Evidence of impairment can clinically be seen in almost half of patients through direct neuropsychological testing, but frank FTD occurs in a limited percentage of patients. [1, 2, 3]

Some propose that frontotemporal lobe dementia with motor neuron disease (FTD/MND) is nosologically distinct; others suggest that it is part of a spectrum of diseases encompassing classic MND at one end and FTD at the other.

The discovery of pathologic transactive response deoxyribonucleic acid (DNA) ̶ binding protein 43 (TDP-43) in ALS and FTD with ubiquitinated inclusions confirms that these are closely related conditions belonging to a new biochemical class of neurodegenerative diseases, the TDP-43 proteinopathies. [4, 5, 6, 7]

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