Mild Neurocognitive Disorder / Mild Cognitive Impairment (MCI)

Last edited on December 17, 2021

Mild Neurocognitive Disorder (also known as Mild Cognitive Impairment, or MCI) is a condition in which individuals demonstrate cognitive impairment with minimal impairment of instrumental activities of daily living (IADLs). Although it can be the first cognitive sign of Alzheimer's Disease (AD), it can also be secondary to other disease processes (e.g. - neurologic, other neurodegenerative disorders, systemic, infectious, or psychiatric disorders). When there is interference with independence in everyday activities, a major neurocognitive disorder needs to be considered instead.

Epidemiology

Prevalence is between 10-20% in adults over 65 years.

Prognosis

Anywhere between 3 to 13% of patients with mild neurocognitive disorder will progress to a major neurocognitive disorder (dementia) each year.^[1]
Not all individuals with MCI will go on to develop a dementia!
- This is a highly heterogeneous group with variable rates of conversion to dementia.
- For example, having multiple domain MCI appears to increase the risk of future dementia.

Comorbidity

Neuropsychiatric symptoms will be present in 35-75% of cases.

Risk Factors

Criterion A

Evidence of modest cognitive decline from a previous level of performance in 1 or more cognitive domains (complex attention, executive function, learning and memory, language, perceptual motor, or social cognition) based on:

Concern of the individual, a knowledgeable informant, or the clinician that there has been a significant decline in cognitive function; and
A substantial impairment in cognitive performance, preferably documented by standardized neuropsychological testing or, in its absence, another quantified clinical assessment.

Criterion B

The cognitive deficits do not interfere with capacity for independence in everyday activities (i.e. - complex instrumental activities of daily living such as paying bills or managing medications are preserved, but greater effort, compensatory strategies, or accommodation may be required).

Criterion C

The cognitive deficits do not occur exclusively in the context of a delirium.

Criterion D

The cognitive deficits are not better explained by another mental disorder (e.g., major depressive disorder, schizophrenia).

Etiology Specifier

Major or Mild Neurocognitive Disorder Due to Alzheimer’s Disease
Major or Mild Frontotemporal Neurocognitive Disorder
Major or Mild Neurocognitive Disorder With Lewy Bodies
Major or Mild Vascular Neurocognitive Disorder
Major or Mild Neurocognitive Disorder Due to Traumatic Brain Injury
Substance/Medication-Induced Major or Mild Neurocognitive Disorder
Major or Mild Neurocognitive Disorder Due to HIV Infection
Major or Mild Neurocognitive Disorder Due to Prion Disease
Major or Mild Neurocognitive Disorder Due to Parkinson’s Disease
Major or Mild Neurocognitive Disorder Due to Huntington’s Disease
Major or Mild Neurocognitive Disorder Due to Another Medical Condition
Major or Mild Neurocognitive Disorder Due to Multiple Etiologies
Unspecified Neurocognitive Disorder

Behaviour Specifier

Specify:

Without behavioural disturbance: If the cognitive disturbance is not accompanied by any clinically significant behavioral disturbance.
With behavioural disturbance (specify disturbance): If the cognitive disturbance is accompanied by a clinically significant behavioural disturbance (e.g. - psychotic symptoms, mood disturbance, agitation, apathy, or other behavioural symptoms).

The DSM-5 criteria notably do not provide additional sub-typing of MCI beyond the specifier criteria. Outside of the DSM-5, a total of 4 MCI subtypes have been proposed, depending on whether the presentation is amnestic/non-amnestic, and single/multiple domain:^[2]

Amnestic MCI, Single Domain (a-MCI-sd)
Amnestic MCI, Multiple Domain (a-MCI-md)
Non-Amnestic MCI, Single Domain (na-MCI-sd)
Non-Amnestic MCI, Multiple Domain (na-MCI-md)

Amnestic MCI, Single Domain (a-MCI-sd)

Amnestic MCI, Single Domain (a-MCI-sd) involves primarily memory impairment with no or minimal involvement of the other cognitive domains.

Amnestic MCI, Multiple Domain (a-MCI-md)

Amnestic MCI, Multiple Domain (a-MCI-md) involves memory impairment as the primary domain affected, but other cognitive domains (e.g. - executive function, attention, language, decision-making, judgment, visuospatial) are also impaired.

Non-Amnestic MCI, Single Domain (na-MCI-sd)

Non-Amnestic MCI, Single Domain (na-MCI-sd) involves impairment of a single, non-memory cognitive domain, such executive function, attention, language, or visuospatial skills.

Non-Amnestic MCI, Multiple Domain (na-MCI-md)

Non-Amnestic MCI, Multiple Domain (na-MCI-md) involves impairment of two or more cognitive domains, neither of which involves memory impairment.

See also: Petersen, Ronald C., et al. Practice guideline update summary: Mild cognitive impairment: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology. Neurology 90.3 (2018): 126-135.

Vitamin D

Improvements in cognition and lipid levels are seen in individuals with long-term supplementation of Vitamin D.^[3]

¹⁾ Farias, S. T., Mungas, D., Reed, B. R., Harvey, D., & DeCarli, C. (2009). Progression of mild cognitive impairment to dementia in clinic-vs community-based cohorts. Archives of neurology, 66(9), 1151-1157.

²⁾ Rapp, S. R., Legault, C., Henderson, V. W., Brunner, R. L., Masaki, K., Jones, B., ... & Thal, L. (2010). Subtypes of mild cognitive impairment in older postmenopausal women: the Women’s Health Initiative Memory Study. Alzheimer disease and associated disorders, 24(3), 248.

³⁾ Fujishiro, H. (2018). Vitamin D3 as a potentially modifiable factor in mild cognitive impairment. J Neurol Neurosurg Psychiatry, jnnp-2018.

Mild Neurocognitive Disorder / Mild Cognitive Impairment (MCI)

Table of Contents

Primer