The neurocognitive disorders discussed in DSM-5 are Delirium, Dementia, and Amnestic and other Cognitive disorders.
The main causes of these disorders are:
• Changes in brain structure: Such changes occur due to brain damage, accidents, violent fights etc. Sometimes internal changes also lead to destruction of brain structure, for e.g. brain tumor leads to destruction of Broca’s area in brain.
• Changes in brain function: Such changes are mainly age related; due to advancing age, the brain function starts deteriorating, for e.g. Alzheimer’s disease in which brain cells start dying.
• Changes in brain chemistry: These changes are also age related.
All these changes lead to destruction of brain tissue in one or the other way.