Screening

Genetic testing

Genetic testing for dementia is not available widely in clinical settings. Genetic testing for screening purposes is indicated when it could contribute to decisions about pregnancy or be used to evaluate risk in family members of a person with frontotemporal dementia (FTD). Testing (for MAPT, GRN, and C9orf72) is generally reserved for patients with a 3-generation pedigree of inheritance.[117][141]​​​​ It may also be reasonable when the evidence for familial transmission is strong in a shorter or less complete pedigree. The family structure should be established and family members who wish to be better informed should be invited to a clinical review with assurances of confidentiality and consent of the FTD patient’s next of kin. When molecular genetic tests are available and the case appears familial, family members are advised to undergo tests provided that facilities for follow-up psychologic support are in place. Pre- and post-test counselling is recommended. Genetic counselling assesses family history, and advises on genetic testing and its impact. It helps individuals and families understand the potential risks and implications of FTD, particularly familial types, and facilitates decisions about genetic testing and management of the condition. Following testing, counselling helps with interpreting results, and provides support and information about inheritance patterns and potential risks for other family members.[118][119]

Fluid biomarkers

Neurofilament light chain (NfL) protein, which reflects neuronal degeneration, can be used as a screening tool for early neurodegenerative processes in genetic cases but also in those not linked to a genetic cause.[75]​​​[142]​​​​​ Levels can be studied in cerebrospinal fluid (CSF) and blood. Although not specific for FTD, NfL levels tend to be higher in FTD than in other dementias and primary psychiatric conditions.[129][137]​​​​ The levels inversely correlate with survival time.[143] ​NfL can also be elevated in the pre-symptomatic stage.[144]​ Phosphorylated neurofilament heavy chain (pNfH) increases closer to clinical onset, suggesting it can help stratify patients according to disease severity.[145]

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