Frontotemporal dementia with motor neuron disease

Frontotemporal dementia with motor neuron disease (FTD-MND), also known as frontotemporal dementia with amyotrophic lateral sclerosis (FTD-ALS), is a devastating neurodegenerative condition in which features of frontotemporal dementia and motor neuron disease (typically amyotrophic lateral sclerosis) co-occur in the same individual. The disease primarily affects the brain's frontal and temporal lobes, leading to progressive changes in behavior, personality, and language, while simultaneously damaging upper and lower motor neurons in the brain and spinal cord, causing progressive muscle weakness, wasting, fasciculations, and eventually respiratory failure. Key clinical features include behavioral changes such as disinhibition, apathy, loss of empathy, compulsive behaviors, and executive dysfunction, alongside motor neuron signs including limb weakness, muscle atrophy, spasticity, dysphagia (difficulty swallowing), and dysarthria (difficulty speaking). The combination of cognitive and motor symptoms leads to rapid functional decline, and the prognosis is generally poorer than for either condition alone, with a median survival of approximately 2–3 years from symptom onset. A significant proportion of cases are linked to a hexanucleotide repeat expansion in the C9orf72 gene, which is the most common genetic cause of both familial FTD and familial ALS. Other associated genes include GRN, TARDBP, FUS, and VCP. Both familial and sporadic forms exist. The underlying pathology most commonly involves TDP-43 protein inclusions in affected neurons. There is currently no cure or disease-modifying treatment. Management is supportive and multidisciplinary, including symptomatic treatment for behavioral symptoms (such as selective serotonin reuptake inhibitors), speech and physical therapy, nutritional support, and respiratory management. Riluzole, used in ALS, may be considered for the motor neuron component, though its benefit in FTD-MND specifically is uncertain.

Common questions about Frontotemporal dementia with motor neuron disease