Cognitive Severity Stages (Normal Aging - Dementia)

The four cognitive severity stages spanning normal aging to dementia are:

No Cognitive Impairment (NCI)

Individuals perceive no decline in cognition and no decline in complex skills that rely on their cognitive abilities. The NCI stage characterizes normal aging individuals, plus those with a cognitively impairing disorder that is not severe enough to produce any change in these abilities. The average duration of NCI is 30 years.

Subjective Cognitive Impairment (SCI)

A perceived or subjective decline in cognitive or functional abilities that does not keep an individual from performing any of their usual or most complex activities. Individuals are aware that there has been a decline in some ability but that they can still compensate to perform it. The SCI stage characterizes normal aging individuals as well as those who are progressively becoming more impaired due to a cognitive disorder. In Alzheimer’s disease, the SCI stage lasts 15 years.

Mild Cognitive Impairment (MCI)

A decline in cognitive abilities such as language, memory reasoning, judgment, or perception that is not due to normal aging. Individuals in the MCI stage of severity can independently drive, shop, cook, pay bills, manage finances, do household chores and other well-learned skills that do not place significant demands upon learning new information. The MCI stage is not seen in normal aging individuals, and is due to one or more cognitive disorders. In Alzheimer’s disease, the MCI stage lasts an average of 7 years.


The level of severity after the MCI stage in most cognitively impairing disorders. Individuals in the dementia stage have declined in ability to perform instrumental activities of daily living, which include well learned skills such as cooking, shopping for groceries, driving to familiar locations, paying bills, doing housework or home repairs, performing well learned hobbies or pastimes. The dementia stage progresses to affect even more well learned skills, called basic activities of daily living, including bathing, dressing, operating a toilet, planning to urinate or defecate so that they get to the toilet on time. Dementia finally progresses to affect walking speech, swallowing and control of the trunk, neck and face. The dementia stage is not seen in normal aging individuals and is due to one or more cognitive disorders. In Alzheimer’s Disease, the dementia stage lasts an average of 7 years.