Distinguishing Mild from Major Neurocognitive Disorder

Diagnostic Criteria

The American Academy of Neurology suggests that cognitive deficits interfere with independence in everyday activities, specifically requiring assistance with complex instrumental activities of daily living (IADLs) such as paying bills or managing medications, to distinguish between mild and major neurocognitive disorder 1, 2
Cognitive deficits do not interfere with capacity for independence in everyday activities in mild neurocognitive disorder, with complex IADLs preserved, though greater effort, compensatory strategies, or accommodation may be required 1, 2
Daily function is overall maintained despite modest cognitive decline in mild neurocognitive disorder 3, 4
Cognitive deficits do interfere with independence in everyday activities in major neurocognitive disorder, with the patient requiring assistance with complex IADLs such as paying bills or managing medications 7, 8

Mild neurocognitive disorder is characterized by modest impairment, typically 1-2 standard deviations below norms on objective cognitive testing 1, 2, 9, 3
Major neurocognitive disorder is characterized by substantial impairment, typically >2 standard deviations below norms on objective cognitive testing 7, 8, 9, 3

The functional assessment remains the definitive criterion for classification between mild and major neurocognitive disorder, rather than the severity of cognitive test performance 1, 2, 3, 4
A patient may have significant cognitive deficits on testing but still qualify as mild neurocognitive disorder if they maintain independence in daily activities with compensatory strategies 1, 2
Even modest cognitive decline qualifies as major neurocognitive disorder if it results in loss of functional independence 7, 8