Symptoms of memory loss are caused by a range of cognitive abilities or a general cognitive decline, and not just memory. Clinicians can diagnose the syndromes of dementia (major neurocognitive disorder) and mild cognitive impairment (mild neurocognitive disorder) based on history, examination, and appropriate objective assessments, using standard criteria such as Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. They can then diagnose the causal subtypes of these syndromes using standard criteria for each of them. Brain imaging and biomarkers are making progress in the differential diagnoses among the different disorders. Treatments are still mostly symptomatic. Copyright © 2014 Elsevier Inc. All rights reserved.