[citation needed] A neurocognitive deficit is a reduction or impairment of cognitive function in one of these areas, but particularly when physical changes can be seen to have occurred in the brain, such as aging related physiological changes or after neurological illness, mental illness, drug use, or brain injury.
[1][2] A clinical neuropsychologist may specialise in using neuropsychological tests to detect and understand such deficits, and may be involved in the rehabilitation of an affected person.
The discipline that studies neurocognitive deficits to infer normal psychological function is called cognitive neuropsychology.
The term neurocognitive is a recent addition to the nosology of clinical Psychiatry and Psychology.
[4] Adding the prefix "neuro-" to the word "cognitive" is an example of pleonasm because analogous to expressions like "burning fire" and "black darkness", the prefix "neuro-" adds no further useful information to the term "cognitive".