Although the presentation is sometimes clear and easy to discern, dementia is the primary diagnostic uncertainty when comparing depression to depression. Thus, both conditions can present with loss of interest and enthusiasm, changes from previous personality traits, memory lapses, and disturbances in sleep and appetite. Differentiating between them requires a comprehensive evaluation, which often involves additional tests and very likely a longitudinal assessment.

It's also worth highlighting the complexity of the issue given how frequently both conditions co-occur. For example, half of all people with dementia experience depressive symptoms, and sometimes the first symptoms of dementia are depressive in nature. Therefore, differentiating between the two is far from easy and requires the expertise of a specialist.