Mental acuity is a measure of the sharpness of the human mind. The measure of mental acuity usually considers focus, memory, concentration and understanding, but does not measure intelligence. This is a way of talking about how well or poorly the brain is functioning, not about its ability to perform complex functions or the amount a person has learned in his or her lifetime.
While there are many tests of mental sharpness available, most people use estimations of mental acuity not as a way of measuring how smart someone is, but as a way to figure out if someone's brain is functioning better or worse than usual due to factors such as distraction, disease, or fatigue.
A decrease or increase in mental abilities is sometimes difficult to measure because a person's mental sharpness is individual. This means that even if brain function could be considered low for a person's age group, that doesn't always imply a loss of brain function. It is important to think about a person's baseline acuity and gauge loss or improvement of function from that standardized degree of sharpness. Often, people themselves recognize a change in mental function before other people begin to notice the effects, and so are able to recognize that change as a symptom better than anyone else.
Some factors affect mental acuity drastically, and often in ways that cannot be changed. Alzheimer's disease is often characterized as causing serious and permanent loss of mental acuity. Other medical problems affecting the brain, such as cancer or encephalitis, can cause a decrease in mental sharpness. Prolonged drug use can also cause permanent damage that will affect the brain's ability to function long after the drugs have left the user's system.
There are also short-term situations that can have a negative effect on mental acuity. Some drugs act on the brain in such a way that mental sharpness is decreased. Other conditions, such as being excessively tired or extremely stressed, can make it difficult for the brain to perform tasks with which it typically has no difficulties. Distractions can also result in an apparent decrease in mental acuity, whether these distractions are internal concerns or external interruptions. Most of these issues are isolated, and acuity is regained after the disturbance is resolved and the brain has had time to adjust itself.
It is also possible to improve mental functions by engaging in activities and strategies that promote these functions. Certain dietary measures are thought to improve mental sharpness, either in the short term or long term. Staying engaged in mental pursuits, such as learning a language or playing a complex game, can also work to improve mental function overall. Exercise is also thought to improve these functions by improving blood flow. Mental acuity can be variable even for the same person and has a lot to do with the body overall, so it is important to take the best possible care of the body in order to achieve the best possible results from the mind.