Neurocognitive Disorders

Neurocognitive disorders are characterized by primary clinical deficits in cognitive functioning that are acquired rather than developmental. Neurocognitive disorders represent a decline from a previously attained level of functioning. Although cognitive deficits are present in many mental disorders (e.g., schizophrenia, bipolar disorders), only disorders whose core features are cognitive are included in the neurocognitive disorders grouping. The four main groupings in this diagnostic category include delirium, amnestic disorder, mild neurocognitive disorder, and the various forms of dementia. Delirium is an acute or subacute neurobehavioral syndrome caused by the transient disruption of normal neuronal activity secondary to systemic disturbances, which might mimic most other psychiatric disorders, given the ability to affect cognition, mood, and perception. By definition, delirium is a syndrome that occurs secondary to a systemic illness process, pharmacological agents used to treat an underlying medical condition, or substances of abuse. Mild neurocognitive disorder (mNCD) is the stage between the expected cognitive decline of normal aging and the more serious decline observed in dementia and is characterized by problems with memory, language, thinking, or judgment. Amnestic disorder is a condition characterized by severe memory impairment relative to the individual’s age and general level of intellectual functioning. In amnestic disorder, recent memory is more impaired than remote memory with usually preserved immediate recall. Of importance the memory impairment is not caused by acute substance intoxication or withdrawal, but rather presumed to be due to an underlying neurological condition. Finally, dementia, also referred as major neurocognitive disorder (MNCD), is an acquired neuropsychiatric disorder, characterized by a clinically significant decline from a previous level of cognitive functioning, where at least two or more cognitive domains (i.e., learning and memory, language, executive functions, attention, psychomotor speed, visuoperceptual or visuospatial abilities, social cognition and judgment) are affected.