You've just been introduced to someone at a party and seconds later, as you try to introduce them to your friend, you realize you can't for the life of you remember their name. You walk into the kitchen to find your glasses but as you enter the room you go blank and can't remember why you are there. Maybe you find yourself constantly late, disorganized, forgetful, and overwhelmed by your responsibilities. Or maybe you feel that you can't focus, concentrate, or even think straight and are tired of walking around in a fog and making jokes about "senior moments". Most of us will develop some degree of decline in cognitive capacity as time progresses, but it does not affect all individuals equally; clear associations exist between the rate and severity of cognitive decline and a variety of factors, including oxidative stress and free radical damage, chronic low-level inflammation, declining hormone levels, endothelial dysfunction, excess body weight, suboptimal nutrition, lifestyle choices, social network, and other existing medical conditions. The good news is that many of these factors can be modified to a significant extent and proactive lifestyle changes, cognitive training and nutritional interventions have been shown to decrease and potentially reverse age-related cognitive decline.
Mild cognitive impairment (MCI) is an intermediate stage between the expected cognitive decline of normal aging and the more serious decline of dementia. It can involve problems with memory, language, thinking and judgment that are greater than normal age-related changes. If you have mild cognitive impairment, you may be aware that your memory or mental function has "slipped." Your family and close friends also may notice a change. But generally these changes aren't severe enough to interfere with your day-to-day life and usual activities. Mild cognitive impairment may increase your risk of later progressing to dementia, caused by Alzheimer's disease or other neurological conditions. But some people with mild cognitive impairment never get worse, and a few eventually get better. Cognitive declines usually begin in our early 30s and are primarily observed in four areas:

(1) Attention or the ability to concentrate on one thing despite other things going on around you. As we get older we become more distractible.
(2) Working-memory or the ability to hold information in our mind for a brief period of time in order to perform some task (such as following driving instructions or figuring out how much to tip). As we get older we're more easily confused as information is not always available when we need it.
(3) Long-term memory, especially recollective memory for details such as names, locations, and who told us something. As we get older we become more forgetful.
(4) Information-processing speed or how quickly we perceive, think, and act. As we get older our thoughts and actions get slower.