612 Neurocognitive Disorders
For mild neurocognitive disorder due to Alzheimer’s disease, code 331.83 (G31.84).
(Note:  Do not  use the additional code for Alzheimer’s disease. Behavioral disturbance
cannot be coded but should still be indicated in writing.)
Diagnostic Features 
Beyond the neurocognitive disorder (NCD) syndro me (Criterion A), the core features of ma-
jor or mild NCD due to Alzheimer’s disease include an insidious onset and gradual pro-
gression of cognitive and beha vioral symptoms (Criterion B) . The typical presentation is
amnestic (i.e., with impairment in memory  and learning). Unusual nonamnestic presen-
tations, particularly visuospa tial and logopenic aphasic vari ants, also exist. At the mild
NCD phase, Alzheimer’s disease manifests typically with impairment in memory and learn-
ing, sometimes accompanied by deficits in executive function. At the major NCD phase,
visuoconstructional/perceptual -motor ability and language w ill also be impaired, partic-
ularly when the NCD is moderate to severe. Social cognition tends to be preserved until
late in the course of the disease. 
A level of diagnostic certainty must be sp ecified denoting Alzheimer’s disease as the
“probable” or “possible” etiology (Criterion C). Probable Alzheimer’s disease  is diagnosed in
both major and mild NCD if there is evidence  of a causative Alzheimer’s disease gene, ei-
ther from genetic testing or from an autosomal dominant family history coupled with au-
topsy confirmation or a genetic test in an affected family member. For major NCD, a
typical clinical picture, without extended plat eaus or evidence of mixed etiology, can also