Differences between mild cognitive impairment and dementia

Cognitive impairment is always a progressive problem with a continuous evolution in most cases. For this reason, the differentiation between normality, the loss of cognitive faculties due to age, mild cognitive impairment and dementia is made difficult by having to set boundaries in a continuous classification.

The clinical situations in which there are memory complaints without frank affectation in the activities of daily living have received various names:

• Age-related memory impairment (AMAE): mild subjective memory complaints, with performance above the limit in short cognitive tests and with normality in daily activities.
• Age-related cognitive impairment (DECAE): mild memory and other cognitive function defects, with performance bordering on normal in psychometric tests. Problems or deterioration are observed only in complex or instrumental tasks.

Concern about the possible relationship of these conditions with incipient dementia has led to important efforts by international committees, and recently mild cognitive impairment has been defined as:

• Cognitive complaints from patients or their family.
• Communication by the patient or his family of a decline in cognitive functioning in the last year.
• Evidence of cognitive disorders by clinical evaluation.
• Deterioration without significant repercussions in daily life.
• Absence of dementia.

Although the definition is not entirely precise, the following data are disturbing and lead to an important clinical and investigative effort. In some studies, similar results have been reported on Alzheimer's disease in complementary tests such as brain imaging, neuropathology, neurochemistry, etc.

In the long term, these patients could suffer deterioration and in some studies it has been reported that the passage of these cases to dementia is very considerable: 12% annually and 80% in 6-year follow-ups. Although the figures in our environment are not so high, it seems clear that, in view of the above, the study of "mild" cognitive impairment is of great interest.

In any case, it is important to carry out a good follow-up of patients with mild cognitive impairment due to its possible progression to dementia. In cases where this is the case, detection and treatment will be earlier, which will result in an improvement in the evolution of these patients.