Diagnostic criteria for dementia

Diagnostic Criteria for Dementia

DSM-5: Neurocognitive Disorder

Dementia is the umbrella term for a number of neurological conditions, of which the major symptom is the decline in brain function due to physical changes in the brain. It is distinct from mental illness.

New diagnostic criteria for dementia were developed and released in 2013.

Dementia is categorised as a Neurocognitive Disorder (NCD) in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The NCD category is then further subdivided into Minor NCD and Major NCD. The term “cognitive” refers to thinking and related processes, and the term “neurocognitive” has been applied to these disorders to emphasise that brain disease and disrupted brain function lead to symptoms of NCD.

The NCD category encompasses the group of disorders that the primary clinical deficit is in cognitive function, which is acquired rather than developmental. Impairment may occur in attention, planning, inhibition, learning, memory, language, visual perception, spatial skills, social skills or other cognitive functions.

In DSM-5, a minor neurocognitive disorder is also medically referred to as Prodromal Disease or Mild Cognitive Disorder (MCI) and is defined by the following criteria:

  • There is evidence of modest cognitive decline from a previous level of performance in one or more of the domains listed below, based on the concerns of the individual, a knowledgeable informant or the clinician; and a decline in neurocognitive performance, typically involving test performance in the range of one and two standard deviations below appropriate norms (i.e. between the third and sixteenth percentiles) on formal testing or equivalent clinical evaluation.
     
  • The cognitive deficits are insufficient to interfere with independence (for example instrumental activities of daily living such as complex tasks such as paying bills or managing medications, are preserved), but greater effort, compensatory strategies, or accommodation may be required to maintain independence.
     
  • The cognitive deficits do not occur exclusively in the context of a delirium.
     
  • The cognitive deficits are not primarily attributable to another mental disorder (for example major depressive disorder and schizophrenia).

For more information: Mild Cognitive Impairment

In DSM-5, a major neurocognitive disorder is defined by the following:

  • There is evidence of substantial cognitive decline from a previous level of performance in one or more of the domains listed below, based on the concerns of the individual, a knowledgeable informant, or the clinician; and a decline in neurocognitive performance, typically involving test performance in the range of two or more standard deviations below appropriate norms (i.e. below the third percentile) on formal testing or equivalent clinical evaluation.
     
  • The cognitive deficits are sufficient to interfere with independence (i.e. requiring minimal assistance with instrumental activities of daily living).
     
  • The cognitive deficits do not occur exclusively in the context of a delirium.
     
  • The cognitive deficits are not primarily attributable to another mental disorder (for example major depressive disorder and schizophrenia).

The DSM-5 details six cognitive domains which may be affected in both Minor and Major NCD.  These cognitive domains (and their associated warning signs/red flags) include:

  • Complex attention - involves sustained attention, divided attention, selective attention and information processing speed
    Warning signs - Patient has increased difficulty in environments with multiple stimuli (TV, radio, conversation). Has difficulty holding new information in mind (recalling phone numbers or addresses just given or reporting what was just said)
  • Executive ability - involves planning, decision making, working memory, responding to feedback, error correction, overriding habits and mental flexibility
    Warning signs - Patient is unable to perform both familiar and complex tasks and projects (at work and at home).  Needs to rely on others to plan instrumental activities of daily living or make decisions. Has problems with abstract thinking, displays loss of initiative as well as poor/decreased judgement
  • Learning and memory - involves immediate memory, recent memory (free recall, cued recall and recognition memory) and long term memory
    Warning signs - Patient repeats self in conversation, often with the same conversation. Cannot keep track of short list of items when shopping or of plans for the day. Requires frequent reminders to orient task at hand, confusion about time and place, and repetitive behaviour
  • Language - involves expressive language (naming, fluency, grammar and syntax) and receptive language
    Warning signs - Patient has significant difficulties with expressive or receptive language. Often uses general terms such as 'that thing' and 'you know what I mean'.  With severe impairment may not recall names of closer friends and family
  • Perceptual - Motor - Visual perception, praxis- involves picking up the telephone, handwriting, using a fork/spoon
    Warning signs - Patient has significant difficulties with previously familiar activities (using tools or, driving a motor vehicle) and navigating in familiar environments
  • Social cognition - involves recognition of emotions and behavioural regulation, social appropriateness in terms of dress, grooming and topics of conversation
    Warning signs - Patient may have changes in behaviour (shows insensitivity to social standards, or make decisions without regard to safety).  Patient usually has little insight into these changes. Becomes socially withdrawn or isolated

    Reference
    American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision. Washington, DC, American Psychiatric Association, 2000.

ICD-10 - Coding for Dementia

The International Classification of Diseases (ICD) is the standard diagnostic tool for epidemiology, health management and clinical purposes.

The ICD is currently under revision through an ongoing Revision Process, and the release date for ICD-11 is 2018.

It is recommended that the ICD-10 be used for dementia until 2018. 

For more information:

WHO International

WHO International Classifications