This cohort study aims to determine if a blood test can aid with diagnosing dementia in anyone presenting with cognitive complaints to a single healthcare network. The investigators will measure levels of a brain protein, Neurofilament light chain (Nfl), and assess changes in language using speech tests. Participants will have a single blood test and speech test, and will be followed up at 12-months to complete questionnaires and cognitive scales over the phone. The speech test will also be completed again at 12-months. Individuals at risk of a Fronto-temporal dementia syndrome will be eligible to complete optional genetic testing involving an 'at home' saliva sample.