All neurocognitive disorders were at one time classified as "dementia," because they involve similar cognitive impairment and decline, and most often affect the elderly. Although Alzheimer's disease accounts for the majority of cases of neurocognitive disorders, several other conditions can similarly affect memory, thinking, and reasoning, and some can also affect the motor system. In addition to Alzheimer's, these conditions include frontotemporal degeneration, Huntington’s disease, Lewy body disease, traumatic brain injury (TBI), Parkinson’s disease, prion disease, and dementia/neurocognitive issues due to HIV infection. These disorders can be categorized and diagnosed as either major in nature or mild (also known as slight cognitive impairment), depending on the severity of an individual's symptoms. For some, such as TBI and HIV, younger as well as older people can be affected. Major cognitive disorder is estimated to affect 1 to 2 percent of people by age 65 and as much as 30 percent of the population by age 85.
Whether diagnosed as mild or major, the mental and behavioral symptoms of the nine recognized neurocognitive disorders are similar, according to the DSM-5, and typically include a decline in thinking skills. This may present as:
- difficulties with planning
- inability to make decisions
- trouble focusing on tasks
- inability to remember the names of objects and people
- struggling to perform daily tasks
- speaking or behaving in ways that are not socially accepted
When there is only a slight decline in one or more of these functions, the disorder is considered mild. When the decline in one of more of these functions is severe, the disorder is considered major. Where an individual falls on the spectrum of neurocognitive impairment is often determined by the degree to which the condition affects his or her level of independence. For both mild and major neurocognitive disorders, though, the decline is typically enough to attract the attention of loved ones or health-care providers, and can be confirmed through testing.
Neurocognitive disorders are not developmental conditions. They are acquired conditions representing underlying brain pathology that results in a decline in faculties. They are caused by brain damage in areas that affect learning and memory, planning and decision making, the ability to correctly use and understand language, hand-eye coordination, and/or the ability to act within social norms, such as dressing appropriately for the weather or occasion, showing empathy, and performing routine tasks. To be diagnosed as a neurocognitive disorder, one's symptoms must be associated with a medical condition, and not another mental health problem, and there can be no evidence of delirium, which is a separate, temporary disorder with similar symptoms.
When a major or mild neurocognitive disorder is suspected, testing can be performed by a neuropsychologist, and the condition can be diagnosed by a neurologist or geriatric psychiatrist. Antidepressants and medications that treat memory loss and other symptoms are available. Ongoing psychotherapy and psychosocial support for patients and families are usually necessary for clear understanding and proper management of the disorder, to establish an adequate caregiving regimen, and to maintain quality of life.