Is mild cognitive impairment (MCI) caused by Alzheimer's disease? What are its signs?

Supervised by Atsushi Iwata, Associate Professor, Department of Neurology, Graduate School of Medicine, University of Tokyo

Mild cognitive impairment caused by Alzheimer's disease (MCI-AD) can be improved by recognizing its signs early and taking appropriate measures. However, MCI-AD is often overlooked because the changes in the condition are not as pronounced as those in the stage of dementia. To detect MCI-AD early, it is very helpful to know the changes and signs seen in the early stage of MCI-AD and dementia.

MCI is difficult to identify

MCI (mild cognitive impairment) is a condition characterized by impairment of some cognitive functions, but no significant impairment of the activities of daily living. On the other hand, dementia makes one forget the experience itself and, therefore, interferes with the activities of daily living. For example, people with dementia have trouble interacting with other people, and have difficulty handling money during shopping, etc. Therefore, people around the person can more easily notice the changes and suspect dementia. However, since people with MCI are able to carry out the basic activities of daily living without any problems, the changes are more likely to remain unnoticed for relatively long periods of time. It is considered that MCI-AD, if left unattended, would eventually lead to the onset of Alzheimer-type dementia in a few years, although there are individual differences. To detect the signs of MCI-AD as early as possible, it is important to have a good awareness of the signs of MCI-AD.

Signs of MCI in daily life

It is important to know the characteristics of MCI-AD, so as not to overlook the signs of MCI.

Clinical definition of MCI-AD

  • The person or his/her family has memory complaints.
  • There is objective evidence of at least one or more cognitive functions (memory, orientation, etc.).
  • Normal activities of daily living
  • No dementia

This section introduces examples of cognitive decline in daily living, not limited to memory disturbance.

Signs seen when going out

People with MCI and dementia experience reduced interest and motivation in things around them due to deteriorated brain function. As a result, some changes occur, such as not paying attention to wearing appropriate clothing when going out and not wanting to go outside.

Signs seen through conversation

In MCI-AD, memory declines over time. For example, people with MCI-AD remember recent news events and events taking place during a trip they made a few weeks ago, but cannot recall details of these events, such as “when” and “where.” Frequent occurrence of these conditions can be taken as a sign of MCI.

Signs seen when cooking

One of the cognitive functions is executive function. As this function declines, it becomes difficult to execute sequenced tasks, such as performing two tasks at the same time, and also difficult to execute actions spontaneously. This leads to the following signs associated with cooking: often burning the pan, leaving the tap water running, or being unable to cook elaborate dishes.

Signs seen at work

As the memory and executive functions decline, the person begins to make more mistakes at work. By asking the same questions over and over, he/she may frustrate the people around. In addition, due to reduced motivation, he/she tends not to learn to use new machinery or work.

Consult an expert if you suspect MCI.

It is believed that MCI-AD will progress to Alzheimer-type dementia if left unattended. However, it remains possible that the onset of dementia can be delayed by early detection and early institution of countermeasures. If MCI is suspected, first consult a specialist or a medical institution, which can also avoid the possibility of its being left unnoticed for a long time.

Posted jointly with “Dementia-NET.”