MT-CO1 and frontotemporal dementia: Three-dimensional stereology was used to assess pyramidal neuron densities and volumes in mPFC layers III and V. Immunohistochemistry evaluated metabolic dysfunction via cytochrome c oxidase subunit 1 (COX1), cytochrome c oxidase subunit 4 (COX4), and 78 kDa glucose-regulated protein expression.<h4>Results</h4>Pyramidal neuron densities were lowered by ≈ 45% and volumes by ≈ 37% within all dementia groups relative to controls, except for FTD densities.