As stated above, a behavioural change may occur before the appearance of any atrophy in the brain in the course of the disease. Because of that, image scanning such as MRI can be insensitive to the early degeneration and it is difficult to detect early-stage bvFTD.In neuropsychology, there is an increasing interest in using neuropsychological tests such as the Iowa gambling task or Faux Pas Recognition test as an alternative to imaging for the diagnosis of bvFTD. Both the Iowa gambling task and the Faux Pas test are known to be sensitive to dysfunction of the orbitofrontal cortex.Faux Pas Recognition test is intended to measure ones ability to detect faux pas types of social blunders (accidentally make a statement or an action that offends others). It is suggested that people with orbitofrontal cortex dysfunction show a tendency to make social blunders due to a deficit in self-monitoring. Self-monitoring is the ability of individuals to evaluate their behaviour to make sure that their behaviour is appropriate in particular situations. The impairment in self-monitoring leads to a lack of social emotion signals. The social emotions such as embarrassment are important in the way that they signal the individual to adapt social behaviour in an appropriate manner to maintain relationships with others.
These include CYLD, OPTN, SQSTM1 and TBK1. These genes have been implicated in the autophagy pathway. No genetic causes of FUS pathology in FTD have yet been reported. Pathology
There are three main histological subtypes found at post-mortem: FTLD-tau, FTLD-TDP, and FTLD-FUS. In rare cases, patients with clinical FTD were found to have changes consistent with Alzheimers disease on autopsy. The most severe brain atrophy appears to be associated with behavioral variant FTD, and corticobasal degeneration.With regard to the genetic defects that have been found, repeat expansion in the C9orf72 gene is considered a major contribution to frontotemporal lobar degeneration, although defects in the GRN and MAPT genes are also associated with it. Diagnosis
FTD is traditionally difficult to diagnose owing to the diverse nature of the associated symptoms. Signs and symptoms are classified into three groups based on the affected functions of the frontal and temporal lobes: These are behavioural variant frontotemporal dementia, semantic dementia, and progressive nonfluent aphasia. An overlap between symptoms can occur as the disease progresses and spreads through the brain regions. Structural MRI scans often reveal frontal lobe and/or anterior temporal lobe atrophy but in early cases the scan may seem normal. Atrophy can be either bilateral or asymmetric. Registration of images at different points of time (e.g., one year apart) can show evidence of atrophy that otherwise (at individual time points) may be reported as normal.