Cognitive deficit

Cognitive deficit is an inclusive term to describe any characteristic that acts as a barrier to the cognition process. 
The term may describe
Cause.
It usually refers to a durable characteristic, as opposed to altered level of consciousness, which may be acute and reversible. Cognitive deficits may be inborn or caused by environmental factors such as brain injuries, neurological disorders, or mental illness.
Screening.
Screening for cognitive impairment in those over the age of 65 without symptoms is of unclear benefit versus harm as of 2020.
Treatment.
Older people with cognitive impairment appear to improve somewhat with light therapy.
Other findings.
Although one would expect cognitive decline to have major effects on job performance, it seems that there is little to no correlation of health with job performance. With the exception of cognitive-dependent jobs such as air-traffic controller, professional athlete, or other elite jobs, age does not seem to impact one’s job performance. This obviously conflicts with cognitive tests given, so the matter has been researched further.
One possible reason for this conclusion is the rare need for a person to perform at their maximum. There is a difference between typical functioning, that is – the normal level of functioning for daily life, and maximal functioning, that is – what cognitive tests observe as our maximum level of functioning. As the maximum cognitive ability that we are able to achieve decreases, it may not actually affect our daily lives, which only require the normal level.
Some studies have indicated that childhood hunger might have a protective effect on cognitive decline. One possible explanation is that the onset of age-related changes in the body can be delayed by calorie restriction. Another possible explanation is the selective survival effect, as the study participants who had a childhood with hunger tend to be the healthiest of their era.