Chapter 5 — Mental, Behavioral and Neurodevelopmental Disorders
Documentation-driven coding: the use / abuse / dependence hierarchy, remission, dementia severity, factitious disorder by proxy, and the two pain-with-psychological-factors codes.
Chapter 5 turns on documentation rather than on sequencing. Remission, dementia severity and the pattern of substance use all require the provider's clinical judgement, and all are assigned only on the basis of provider documentation. The substance-use hierarchy — use, abuse, dependence — is the single most frequently misapplied rule in the chapter.
Pain related to psychological factors#
| Code | When | With G89? |
|---|---|---|
F45.41 Pain disorder exclusively related to psychological factors | Pain that is exclusively related to psychological disorders | NEVER No. As the Excludes1 note at category G89 indicates, a code from G89 is not assigned with F45.41 |
F45.42 Pain disorders with related psychological factors | There is documentation of a psychological component for a patient with acute or chronic pain | ALWAYS Yes — use with a code from category G89 |
The substance use, abuse and dependence hierarchy#
When provider documentation refers to use, abuse and dependence of the same substance, only one code is assigned — and dependence always wins. The hierarchy applies within a single substance, not across substances: a patient with alcohol dependence and cannabis use gets one code for each substance.
| Documented for the same substance | Assign only |
|---|---|
| Use and abuse | the code for abuse |
| Abuse and dependence | the code for dependence |
| Use, abuse and dependence | the code for dependence |
| Use and dependence | the code for dependence |
| Situation | Rule |
|---|---|
In remission — categories F10–F19 with -.11, -.21, -.91 | Requires the provider's clinical judgement and is assigned only on the basis of provider documentation, unless the classification instructs otherwise |
| Mild substance use disorder in early or sustained remission | Classified to the appropriate codes for substance abuse in remission |
| Moderate or severe substance use disorder in early or sustained remission | Classified to the appropriate codes for substance dependence in remission |
Unspecified psychoactive substance use — F10.9-, F11.9-, F12.9-, F13.9-, F14.9-, F15.9-, F16.9-, F18.9-, F19.9- | Assigned only on provider documentation, only when the definition of a reportable diagnosis is met (Section III), and only when the use is associated with a substance related disorder or medical condition and that relationship is documented by the provider |
| Medical conditions due to psychoactive substance use, abuse and dependence | Not classified as substance-induced disorders. Assign the code for the medical condition as the Index directs, plus the appropriate use, abuse or dependence code |
| Blood alcohol level | A code from category Y90 may be assigned when the level is documented and the patient's provider has documented a condition classifiable to category F10. The blood alcohol level itself need not be documented by the provider |
Factitious disorder — who gets the diagnosis?#
| Person | Code | Notes |
|---|---|---|
| The patient who falsely reports or causes their own signs or symptoms — Munchausen's syndrome | F68.1- Factitious disorder imposed on self | — |
| The caregiver who falsely reports or causes illness or injury in another person under their care — Munchausen's syndrome by proxy (MSBP) | F68.A Factitious disorder imposed on another | ALWAYS The perpetrator, not the victim, receives this diagnosis. F68.A goes on the perpetrator's record |
| The victim of a patient with MSBP | T74.- Adult and child abuse, neglect and other maltreatment, confirmed, or T76.- suspected | See Section I.C.19.f |
Dementia — etiology and severity#
| Point | Rule |
|---|---|
| Classification basis | Categories F01, F02 and F03 classify dementia on the basis of the etiology and the severity — unspecified, mild, moderate or severe |
| Who decides severity | Selection of the appropriate severity level requires the provider's clinical judgement, and codes are assigned only on the basis of provider documentation, unless the classification instructs otherwise |
| Severity not documented | Assign the appropriate code for unspecified severity |
| Severity progresses during an inpatient stay | If a patient is admitted to an inpatient acute care hospital or other inpatient facility with dementia at one severity level and it progresses to a higher level, assign one code for the highest severity level reported during the stay |
Practice questions#
Q1A progress note documents “alcohol use”, a consultation documents “alcohol abuse”, and the discharge summary documents “alcohol dependence”. How many codes from category F10 are assigned?
- AThree — one for each pattern documented
- BTwo — abuse and dependence
- COne — the code for dependence
- DOne — the code for use, as the earliest documentation
Show answer & rationale
Correct answer: C. One — the code for dependence
Rationale. Guideline I.C.5.b.2 states that when provider documentation refers to use, abuse and dependence of the same substance, only one code should be assigned to identify the pattern of use, following a hierarchy in which dependence outranks abuse and abuse outranks use. With all three documented for the same substance, only the code for dependence is assigned.
Q2A patient is treated for alcohol induced acute pancreatitis. The provider documents alcohol dependence. What is assigned?
- A
F10.288alone, as a combination code - B
K85.2-andF10.20 - C
K85.2-alone - D
F10.20alone
Show answer & rationale
Correct answer: B. K85.2- and F10.20
Rationale. Guideline I.C.5.b.4 states that medical conditions due to substance use, abuse and dependence are not classified as substance-induced disorders, and that the diagnosis code for the medical condition should be assigned as directed by the Alphabetic Index along with the appropriate psychoactive substance use, abuse or dependence code. The guideline uses this exact example and states that it would not be appropriate to assign F10.288.
Q3A caregiver is found to have deliberately caused illness in a child in her care. Who receives code F68.A?
- AThe child
- BThe caregiver
- CBoth
- DNeither — use
T74.-only
Show answer & rationale
Correct answer: B. The caregiver
Rationale. Guideline I.C.5.c states that in Munchausen's syndrome by proxy the perpetrator, not the victim, receives the diagnosis, and that F68.A factitious disorder imposed on another is assigned to the perpetrator's record. For the victim, the appropriate code from category T74 confirmed or T76 suspected abuse, neglect and other maltreatment is assigned.
Q4A patient is admitted with mild dementia. During the stay the dementia is documented as progressing to moderate severity. What is assigned?
- AOne code for mild severity
- BOne code for moderate severity
- CTwo codes — mild and moderate
- DOne code for unspecified severity
Show answer & rationale
Correct answer: B. One code for moderate severity
Rationale. Guideline I.C.5.d states that if a patient is admitted to an inpatient acute care hospital or other inpatient facility setting with dementia at one severity level and it progresses to a higher severity level, assign one code for the highest severity level reported during the stay. This differs from the pressure ulcer rule at I.C.12.a.6, which requires two codes in the analogous situation.
Q5Which code may be assigned with a code from category G89?
- A
F45.41 - B
F45.42 - CBoth
- DNeither
Show answer & rationale
Correct answer: B. F45.42
Rationale. Guideline I.C.5.a directs that F45.41 is assigned for pain exclusively related to psychological disorders and that, as indicated by the Excludes1 note under category G89, a code from category G89 should not be assigned with F45.41. Code F45.42, pain disorders with related psychological factors, should be used with a code from category G89 where there is documentation of a psychological component for a patient with acute or chronic pain.
Scenarios#
A patient is brought to the emergency department after a single-vehicle crash. The laboratory reports a blood alcohol level of 210 mg/100 mL. The attending physician documents “alcohol abuse” and treats a closed fracture of the left clavicle.
Show coded answer & rationale
| Seq | Code | Description |
|---|---|---|
| 1 | S42.022- | Displaced fracture of shaft of left clavicle, with the appropriate 7th character — principal diagnosis |
| 2 | F10.10 | Alcohol abuse, uncomplicated |
| 3 | Y90.6 | Blood alcohol level of 200-239 mg/100 ml — verify the exact code in the Tabular List |
| 4 | External cause | the applicable transport accident code(s), place of occurrence, activity and external cause status per Chapter 20 |
Rationale. Guideline I.C.5.b.5 permits a code from category Y90 when the blood alcohol level is documented and the patient's provider has documented a condition classifiable to category F10, and states that the blood alcohol level itself does not need to be documented by the patient's provider. Section I.B.14 lists blood alcohol level among the items that may be coded from another clinician's documentation and restricts it to a secondary diagnosis. The provider-documented alcohol abuse is what makes the Y90 code assignable.
Guideline: Section I.C.5.b.5, I.B.14
A psychiatry note documents “severe opioid use disorder, in sustained remission” for a patient in a maintenance programme, seen for an unrelated dermatological complaint.
Show coded answer & rationale
| Seq | Code | Description |
|---|---|---|
| 1 | Reason for visit | the dermatological condition, as first-listed diagnosis |
| 2 | F11.21 | Opioid dependence, in remission — verify in the Tabular List |
Rationale. Guideline I.C.5.b.1 states that moderate or severe substance use disorders in early or sustained remission are classified to the appropriate codes for substance dependence in remission, while mild substance use disorders in early or sustained remission are classified to the codes for substance abuse in remission. The guideline also states that remission codes require the provider's clinical judgement and are assigned only on the basis of provider documentation. Note that methadone maintenance for opioid dependence is specifically excluded from category Z79 by Section I.C.21.c.3 — the appropriate code for the drug use, abuse or dependence is assigned instead.
Guideline: Section I.C.5.b.1, I.C.21.c.3
A screening questionnaire in the record records occasional cannabis use. There is no provider documentation linking the cannabis use to any disorder or medical condition, and the encounter is for an unrelated acute condition.
Show coded answer & rationale
| Seq | Code | Description |
|---|---|---|
| 1 | Reason for visit | the acute condition |
| 2 | — | no code from F12.9- is assigned |
Rationale. Guideline I.C.5.b.3 restricts the unspecified psychoactive substance use codes in three ways: they should only be assigned based on provider documentation, only when they meet the definition of a reportable diagnosis under Section III, and only when the psychoactive substance use is associated with a substance related disorder or a medical condition and such a relationship is documented by the provider. None of the three is satisfied here.
Guideline: Section I.C.5.b.3; Section III
Primary sources#
- ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027CMS — the source document for every page on this site (effective 1 Oct 2026)
- NCHS ICD-10-CM files — Tabular List, Index, POA exempt listOfficial code files, addenda and the list of codes exempt from POA reporting
- ICD-10 Coordination and Maintenance CommitteeWhere code proposals are debated; agendas, summaries and meeting materials
- CMS ICD-10 homeCode sets, transition guidance and Medicare coding policy
- AHA Coding ClinicOfficial coding advice from the AHA Central Office — subscription required
- HHS OIG Work PlanActive audit topics — useful for prioritising internal coding audits
- MEDESUN Medical Coding AcademyTraining, credential preparation and audit services by the author