Diagnosis
According to DSM-IV diagnosis is mainly clinical including changed behaviors, changes in language and others, using also image exams and neuropsychological tests.
Structural MRI scans often reveal frontal lobe and/or anterior temporal lobe atrophy but in early cases the scan may seem normal. Atrophy is often asymmetric. Registration of images at different time points (e.g. one year apart) can show evidence of atrophy in two cross-sectional images that may be reported as normal. This is a useful diagnostic technique. However, many research groups are currently looking at ways of making an early diagnosis of FTD using other techniques (magnetic resonance spectroscopy, functional imaging, cortical thickness measurements etc.). FDG-PET scans classically show frontal and/or anterior temporal hypometabolism, which helps differentiate from Alzheimer's disease. The PET scan in Alzheimer's disease classically shows biparietal hypometabolism. Meta-analyses based on imaging methods have shown that frontotemporal dementia mainly affects a frontomedian network discussed in the context of social cognition or 'theory of mind'. This is entirely in keeping with the notion that, on the basis of cognitive neuropsychological evidence, the ventromedial prefrontal cortex is a major locus of dysfunction early on in the course of the behavioural variant of frontotemporal degeneration. The language subtypes of frontotemporal lobar degeneration (semantic dementia and progressive nonfluent aphasia) can be regionally dissociated by imaging approaches in vivo.
Read more about this topic: Frontotemporal Dementia