# 207 - 6D71 Mild neurocognitive disorder

# 6D71 Mild neurocognitive disorder

Clinical Descriptions and Diagnostic Requirements for ICD-11 Mental, Behavioural or Neurodevelopmental Disorders
Delirium, other specified cause
Essential (required) features
• All diagnostic requirements for delirium are met.
• The delirium is presumed to be attributable to an identified cause that is not adequately 
captured by any of the other available delirium categories.
• This judgement depends on establishing the following:
• The specified cause is known to be capable of producing delirium.
• The course of the delirium (e.g. onset, trajectory of symptoms, response to treatment) is 
consistent with the specified cause.
Note: the ICD-11 diagnosis corresponding to the presumed etiology should also be assigned.
Delirium, unknown or unspecified cause
Mild neurocognitive disorder
Essential (required) features
• The presence of mild impairment in one more or cognitive domains (e.g. attention, 
executive function, language, memory, perceptual-motor abilities, social cognition) 
relative to expectations for age and general premorbid level of neurocognitive functioning 
is required for diagnosis.
• Impairment represents a decline from the individual’s previous level of functioning.
• Neurocognitive impairment is not severe enough to interfere significantly with an 
individual’s ability to perform activities related to personal, family, social, educational and/
or occupational functioning or other important functional areas.
• Evidence of mild neurocognitive impairment is based on:
• information obtained from the individual, an informant or clinical observation;
• objective evidence of impairment as demonstrated by standardized neuropsychological/
cognitive testing or, in its absence, another quantified clinical assessment.
• Neurocognitive impairment is not attributable to normal ageing.
• Neurocognitive impairment may be attributable to an underlying acquired disease of the 
nervous system, a trauma, an infection or other disease process affecting the brain, use 
of specific substances or medications, nutritional deficiency or exposure to toxins, or the 
etiology may be undetermined.
6D70.Y
Neurocognitive disorders | Mild neurocognitive disorder
6D70.Z
6D71

609
Neurocognitive disorders
• The symptoms are not better explained by another neurocognitive disorder, substance 
intoxication or substance withdrawal, or another mental disorder (e.g. attention 
deficit hyperactivity disorder or other neurodevelopmental disorder, schizophrenia or 
another primary psychotic disorder, a mood disorder, post-traumatic stress disorder, a 
dissociative disorder).
Note: cases referred to elsewhere as “mild cognitive impairment” are referred to in ICD-11 
as “mild neurocognitive disorder”. When mild neurocognitive disorder is due to a disease, 
condition or injury classified elsewhere (including disorders due to substance use), the diagnostic 
code corresponding to that disease, condition or injury should assigned in addition to mild 
neurocognitive disorder. When the etiological condition is unknown, the diagnosis 8A2Z 
Disorders with neurocognitive impairment as a major feature, unspecified, may be assigned 
in addition to mild neurocognitive disorder.
Potentially explanatory medical conditions (examples)
Mild neurocognitive disorder may be caused by any of the specified causes of dementia (see 
specific types of dementia, p. 621). In addition, mild neurocognitive disorder may be caused by: 
• anaemias or other erythrocyte disorders;
• certain infectious or parasitic diseases (e.g. meningitis);
• diseases of the circulatory system (e.g. coronary atherosclerosis);
• diseases of the nervous system (e.g. cerebral palsy, epilepsy or seizures, hypertensive 
encephalopathy, hypoxic-ischaemic encephalopathy);
• endocrine diseases (e.g. diabetes mellitus, hypothyroidism);
• intracranial injury;
• metabolic disorders (e.g. hypo-osmolality or hyponatraemia);
• neoplasms of the brain or central nervous system;
• nutritional disorders (e.g. vitamin B12 deficiency).
Additional clinical features
• Mild declines in complex activities may be typically present (e.g. using transportation, meal 
preparation), while basic activities of daily living (e.g. dressing, bathing) are preserved. The 
individual may engage in compensatory strategies to maintain independence in everyday 
functioning.
• Behavioural and psychological symptoms are commonly associated with mild 
neurocognitive disorder (e.g. depressed mood, sleep disturbance, anxiety).
Neurocognitive disorders | Mild neurocognitive disorder

Clinical Descriptions and Diagnostic Requirements for ICD-11 Mental, Behavioural or Neurodevelopmental Disorders
Boundary with normality (threshold)
• Normal ageing is typically associated with some degree of cognitive change. A diagnosis 
of mild neurocognitive disorder does not apply if performance is consistent with 
expectations for the individual’s age, based on age-related norms for performance on 
standardized assessment.
Course features
• The course of neurocognitive impairment in mild neurocognitive disorder may be static 
or progressive, or may resolve or improve depending on the specific etiology and available 
treatment options.
• In some cases, mild neurocognitive disorder may represent an early presentation of an 
underlying disease of the nervous system that may later meet the diagnostic requirements 
for dementia.
Developmental presentations
• Mild neurocognitive disorder can occur at any point across the lifespan, with 
risk and prevalence depending on the underlying etiology. Overall risk of mild 
neurocognitive disorder increases with age because of the increased prevalence of possible 
causal conditions.
Culture-related features
• Performance during clinical assessment may vary according to cultural and/or linguistic 
factors. When assessing impairment in neurocognitive functioning and activities of 
daily living, cultural and linguistic factors should be considered and accounted for when 
possible.
• When standardized neuropsychological/cognitive testing is utilized for determination of 
neurocognitive impairment, performance should be measured with appropriately normed, 
standardized tests. In situations where appropriately normed and standardized tests 
are not available, assessment of neurocognitive functioning requires greater reliance on 
clinical judgement. (See the section on general cultural considerations for neurocognitive 
disorders above for additional information and examples.)
Neurocognitive disorders | Mild neurocognitive disorder

611
Neurocognitive disorders
Boundaries with other disorders and conditions (differential diagnosis)
Boundary with delirium
Delirium is characterized by a disturbance of attention, orientation and awareness, with transient 
symptoms that may fluctuate depending on the underlying causal condition or etiology. Delirium 
typically presents with significant confusion or global neurocognitive impairment, in contrast 
to mild neurocognitive disorder, in which there is mild impairment in one or more cognitive 
domains that does not interfere significantly with functioning.
Boundary with amnestic disorder
Amnestic disorder is characterized by prominent memory impairment relative to expectations 
for age and general premorbid level of neurocognitive functioning that is severe enough to 
result in significant impairment in personal, family, social, educational, occupational or other 
important areas of functioning, in the absence of other significant neurocognitive impairment. 
While specific presentations of mild neurocognitive disorder may primarily affect memory, the 
memory impairment is not severe enough to interfere significantly with functioning in everyday 
skills and tasks.
Boundary with dementia
Dementia is characterized by marked impairment in two or more cognitive domains that is severe 
enough to cause significant impairment in personal, family, social, educational, occupational or 
other important areas of functioning. Neurocognitive deficits in mild neurocognitive disorder 
may be in similar areas, but are not severe enough to cause significant impairment in functioning.
Boundary with mild cognitive symptoms in other mental disorders
Mild cognitive symptoms may be a characteristic or associated feature of a wide range of mental 
disorders (e.g. attention deficit hyperactivity disorder, schizophrenia and other primary psychotic 
disorders, mood disorders, anxiety and fear-related disorders, post-traumatic stress disorder, 
dissociative disorders). If the neurocognitive impairment is better explained by another mental 
disorder, an additional diagnosis of mild neurocognitive disorder should not be assigned.
Boundary with sleep-wake disorders
Memory and other neurocognitive impairment is frequently reported by individuals with sleep 
disturbance or sleep-wake disorders, such as insomnia and sleep apnoea. If the neurocognitive 
impairment is better explained by a sleep-wake disorder, an additional diagnosis of mild 
neurocognitive disorder should not be assigned.
Neurocognitive disorders | Mild neurocognitive disorder