Common Major and Mild Neurocognitive Disorders: Alzheimer Disease, Frontotemporal, Lewy Body, and Vascular Types

Abstract

Major and mild neurocognitive disorders are often managed by physicians in multiple specialties including primary practice, psychiatry, geriatric medicine, and neurology. Major and mild neurocognitive disorders are classified according to the known etiological or pathological entities underlying the cognitive impairment. For certain types, the diagnosis depends on the presence of a potentially causative entity, such as Parkinson disease, other parkinsonism, vascular disease, or traumatic brain injury. For other etiologies, such as Alzheimer disease, frontotemporal lobar degeneration, and Lewy body disease, the diagnosis is based primarily on the cognitive, behavioral, and functional symptoms. The differentiation among these multiple types of neurocognitive disorders becomes more evident at the level of major neurocognitive disorder than at the level of mild neurocognitive disorder, but characteristic features can be present at the mild level as well. For many types, international expert groups have developed specialized consensus criteria based on clinicopathological correlation with underlying brain pathology. This section reviews the diagnostic guidelines, clinical presentations, differential diagnosis, and treatment considerations of the four main types: neurocognitive disorder due to Alzheimer disease, frontotemporal neurocognitive disorder, neurocognitive disorder due to Lewy bodies, and vascular neurocognitive disorder.