Alzheimer's Disease Subtype of Major and Minor Neurocognitive Disorders

A. Major: Meets criteria for Major Neurocognitive Disorder, with memory being one of the impaired domains.

Minor: Meets criteria for Minor Neurocognitive Disorder with memory impairment AND there is clear supporting evidence for the Alzheimer etiology (e.g., a positive test for a known mutation in an Alzheimer’s disease associated gene), or with evolving research, documentation based on biomarkers or imaging.

B. Early and prominent impairment in the Memory domain (rarely, other domains such as visuoconstructive perceptual domain may be prominently affected, but Alzheimer’s disease would not be diagnosed without clear supporting imaging, biomarker or genetic evidence).

Major: Deficits are observed in at least one other domain, often Executive Ability, and as the disease progresses, in additional domains.

Minor: Only Memory may be affected, but deficits in Executive Abilities are common.

C. The course is characterized by gradual onset and continuing cognitive decline

D. Evidence from history, examination, and investigations that deficits are not wholly or primarily attributable to other disorders. However, other such disorders may coexist.

For a complete rationale, please see the Neurocognitive Disorders Proposal for DSM-5.

{Criteria for the Alzheimer’s disease subtype of Major or Minor Neurocognitive Disorder are offered as a sample of how specific etiologies would be coded.} 

Alzheimer's disease is a neurodegenerative disorder, typically seen in late life, but can occur earlier. It is marked by insidious onset, gradual decline, and typically an early prominent memory loss. For Major Neurocognitive Disorder this typical clinical picture has excellent predictive value for the Alzheimer subtype and is all that is required for a diagnosis of the Alzheimer subtype, although additional evidence adds to the certainty of diagnosis. For less typical clinical profiles such as posterior coritical atrophy or visual variant of AD, additional supportive evidence such as typical neuroimaging patterns of atrophy is required. For Minor Neurocognitive Disorder, because of the modest predictive value of the clinical picture alone and the significant social consequences of an Alzheimer diagnosis, the Alzheimer’s disease subtype is not commonly diagnosed. However, such a diagnosis is possible if there is sufficient information available (e.g., a positive genetic test for dominantly inherited AD, or as the field develops, evidence that certain imaging markers, atrophy of medial temporal lobe structures on MRI, temporoparietal hypometabolism on FDG PET, amyloid deposition on PET scanning or markers for tau and abeta in the CSF are sufficiently predictive of an underlying AD pathology).

While patients in memory disorders clinics who meet current research criteria for Mild Cognitive Impairment (similar to Minor Neurocognitive Disorder with impaired memory) progress to dementia of the Alzheimer type at the rate of 12-15% per year and have neuropathological evidence of both neurodegeneration and cerebrovascular disease, population-based studies show a much lower rate of progression with some individuals improving. Research is ongoing into what specific features of MCI might reliably indicate the presence of prodromal Alzheimer’s disease. Until those features can be identified, the Neurocognitive Disorders Work Group does not feel that the predictive value of Minor Neurocognitive Disorder (minor NCD) with memory impairment is sufficient for a diagnosis of Alzheimer’s disease. However, such a diagnosis might be made in an individual with an autosomal dominant family history or positive test for a mutation in an autosomal dominant "AD gene", or, after further research, with clearly predictive biomarkers or imaging studies.

• This is an area in which knowledge is evolving rapidly; the procedures described above are increasingly used in clinical practice at tertiary care centers and outside the US. It is possible some of them will enter standard use in the near future.
• Previous terminology was revised to recognize the clinical and pathological evidence that comorbidity is the norm in the population at large, that having cerebrovascular disease does not preclude also having Alzheimer’s disease and vice versa, and in the presence of both, it is not useful to arbitrarily assign causality to one or the other.
• There is little scientific rationale for retaining the distinction between early and late onset, as the underlying pathology is the same, and the threshold of age 65 is arbitrary at best.

NOTE: Alzheimer’s disease (AD) is often associated with psychotic features including delusions and visual and auditory hallucinations, with depression, and with other behavioral disturbances. Criteria have been proposed for Psychosis and for Depression of Alzheimer’s Disease. There is ongoing discussion of how psychosis, depression, and other behavioral disturbances in Alzheimer’s disease (and more broadly in other Neurocognitive Disorders) will be coded. One option is to use fifth digit specifiers for presence or absence of specific behavioral symptoms across Major and Minor Neurocognitive Disorders – i.e., psychosis, depression, agitation, aggression, apathy, wandering,etc). Another is to tailor them to specific disorders. It has also been proposed that separate criteria be provided for Psychosis and Depression of AD along the lines of those below. Comments regarding this issue are welcome.

Criteria for Psychosis of AD:

A. Characteristics symptoms: Delusions or auditory or visual hallucinations

B. Primary diagnosis: AD: Chronology of onset of symptoms of dementia prior to onset of psychotic symptoms

C. Duration: >1 month, although the delusions and hallucinations may be intermittent; symptoms cause clinically significant distress or functional disruption

D. Symptoms not exclusively during delirium

E. Symptoms not due to direct physiological effects of a substance and cannot be better accounted for schizophrenia or other psychotic disorder

Rationale

(1) Public health importance: High prevalence & incidence

(2) Associated with:  More agitation, aggression, More rapid cognitive decline, Greater caregiver distress, earlier institutionalization, and higher cost of care

(3) Persistence or recurrence common

(4) Aggregates in families

(5) Clinical differences between AD + Psychosis and both AD without psychosis and Psychosis without AD

(6) Specific treatment considerations

Criteria for Depression of AD:

A. 3 (or more) of 10 listed symptoms under Major Depressive Disorder

B. Primary diagnosis: AD

C. Duration: > 2 weeks; Symptoms cause clinically significant distress or functional disruption

D. Symptoms not exclusively during delirium

E. Symptoms not due to direct physiological effects of a substance and cannot be better accounted for by another disorder

Rationale

(1) Public health importance: High prevalence and incidence

(2) Associated with: Higher mortality and Higher cost of care

(3) Persistence or recurrence common

(4) Clinical differences between AD + depression and both AD without depression and Depression without AD

(5) Specific treatment considerations

References:

(1) Bacanu S-A et al., Am J Geriat Psychiatry 2005

(2) Devanand D, et al., Arch Gen Psychiatry 1997

(3) Jeste and Finkel, Am J Geriat Psychiat 2000

(4) Olin et al., Am J Geriat Psychiatry, 2002

(5) Paulsen et al,  Neurology. 2000;54:1965 (6) Ropacki S, et al, Am J Psychiatry 2005

(7) Sweet R, et al., Brain, 2009

(8) Watson LC, et al., Am J Geriat Psychiatry, 2009

Recommendations for severity criteria for this disorder are forthcoming.  We encourage you to check our Web site regularly for updates.