To report prominent auditory hallucinations in the context of behavioral variant frontotemporal dementia (bvFTD).

Hallucinations are rare in sporadic and familial FTD, and when present, these are almost always associated with the C9orf72 hexanucleotide expansion and not mutations in MAPT.

The patient is a right-handed woman who had a mutation in MAPT identified clinically when she was asymptomatic.  She has numerous relatives with bvFTD but none experienced hallucinations of any kind. Mild executive and language dysfunction began in her late 40s along with recurrent auditory hallucinations. She perceived three distinct external voices who made threats against her and her family, often stating that they or others will cause harm to her children or grandchildren. She was fearful of leaving her home, stopped working, and had difficulty sleeping and trouble interacting with others in social situations. She did not have any other delusions, paranoid thoughts or mood changes, and maintained insight about the hallucinations. Olanzapine initially improved her symptoms dramatically, but was changed to quetiapine and risperidone. She has been maintained on these two antipsychotic agents over 2 years. The voices continue to be perceived almost daily but are minimally threatening. She is now dependent on others for complex ADLs, has apathy, disinhibition and ritualistic behavior, and is impaired on several neuropsychologic measures. Serial MRI of the brain shows progressive bilateral frontal and temporal atrophy with significant atrophy bilaterally in the insula. FDG-PET scan of the brain shows mild patchy hypometabolism in the bilateral frontal and temporal lobes, with severe bilateral caudate hypometabolism.

Recurrent and persistent auditory hallucinations can occur in bvFTD. The underlying substrate for this feature is likely related to frontosubcortical neural network dysfunction, but considering that this topography is present in most bvFTD patients, the precise mechanism for auditory hallucinations in this patient is unclear.