Biofluid biomarkers in distinguishing young-onset dementia from primary psychiatric disorders

There has been growing interest in the role of biofluid biomarkers to aid the diagnosis of dementia in older people. However, less attention has been given to younger people who have dementia (young-onset dementia), who frequently experience misdiagnoses of primary psychiatric disorders diagnostic delay and challenges accessing appropriate care.

We describe 12 studies from the previous 2 years of which the majority have investigated the role of neurofilament light chain protein (NfL) in blood and cerebrospinal fluid in distinguishing young-onset dementia from primary psychiatric disorders. Synaptic and astrocytic biomarkers were also investigated. Sample sizes ranged from n = 46 to n = 999 and studies were mostly from Australia and the Netherlands.

The major finding from this review was that NfL has very high sensitivity and specificity in differentiating a range of young-onset dementias (Alzheimer's dementia, behavioural-variant frontotemporal dementia) from PPD (schizophrenia, bipolar affective and major depressive disorders). NfL is easily accessible via the blood, so there is significant potential that a blood test could be available to make this dichotomisation. Further research is required to support clinical translation such as changes of NfL with disease progression and standardising analytic techniques.