(Plus the code for 
the relevant sub-
stance/medication-
induced major neu-
rocognitive disor-
ders if substances 
or medications 
play a role in the 
etiology.)331.83 (G31.84) 
(Plus the code for 
the relevant sub-
stance/medication-
induced mild neuro-
cognitive disor-
ders if substances 
or medications play 
a role in the etiol-
ogy. Do not use ad-
ditional codes for 
the presumed 
etiological medical 
conditions.)
Unspecified neuro-
cognitive disorderNo additional medical 
code799.59 (R41.9) 799.59 (R41.9)
aCode first, before code for major neurocognitive disorder.
bCode fifth character based on symptom specifier: .x0 without behavioral disturbance; .x1 with be-
havioral disturbance (e.g., psychotic symptoms, mo od disturbance, agitatio n, apathy, or other be-
havioral symptoms).
cNote:  Behavioral disturbance specifier cannot be coded but should still be indicated in writing.
dSee “Substance/Medication-Induced Majo r or Mild Neurocognitive Disorder.”Etiological subtypeAssociated etiological 
medical code for major 
neurocognitive disorderaMajor neurocogni-
tive disorder codebMild neurocogni-
tive disorder codec