2026 ICD-10-CM Diagnosis Code G31.83Neurocognitive disorder with Lewy bodies

ICD-10-CM Codes›G00–G99›G30-G32›G31

ICD-10-CM G31.83
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G31.83 is a billable ICD-10-CM diagnosis code for neurocognitive disorder with Lewy bodies. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Neurocognitive disorders.

Code Identity

ICD-10-CM Code
G31.83
Billable Status
Yes — Valid for Submission
Code Describes
Neurocognitive disorder with Lewy bodies
Short Description
Neurocognitive disorder with Lewy bodies
Same as the full description in the CMS dataset.
Parent Code
G31.8
Other specified degenerative diseases of nervous system

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG30-G32Other degenerative diseases of the nervous system
CategoryG31Other degenerative diseases of nervous system, not elsewhere classified
This CodeG31.83Neurocognitive disorder with Lewy bodies

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Dementia due to Lewy body disease
  • Dementia with behavioral disturbance
  • Diffuse Lewy body disease with spongiform cortical change
  • Disorder of autonomic nervous system due to senile dementia of Lewy body type
  • Early onset dementia due to Lewy body disease
  • Late onset dementia due to Lewy body disease
  • Lewy body dementia with behavioral disturbance
  • Lewy body disease
  • Parkinsonism with dementia of Guadeloupe

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Lewy body dementia
  • Lewy body disease

Use Additional Code

  • code, if applicable, to identify mild neurocognitive disorders due to known physiological condition F06.7

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Dementia(degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)
      • with
        • Lewy bodies
    • Dementia(degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)
      • with
        • Lewy bodies
          • with behavioral disturbance
    • Dementia(degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)
      • Lewy body
    • Dementia(degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)
      • Lewy body
        • with behavioral disturbance
    • Disease, diseased
      • Lewy body (dementia)
    • Disease, diseased
      • Lewy body (dementia)
        • with behavioral disturbance
    • Disorder(of)
      • neurocognitive
        • with Lewy bodies
    • Lewy body(ies) (disease)

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS011
Neurocognitive disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Lewy Body Disease

    a neurodegenerative disease characterized by dementia, mild parkinsonism, and fluctuations in attention and alertness. the neuropsychiatric manifestations tend to precede the onset of bradykinesia, muscle rigidity, and other extrapyramidal signs. delusions and visual hallucinations are relatively frequent in this condition. histologic examination reveals lewy bodies in the cerebral cortex and brain stem. senile plaques and other pathologic features characteristic of alzheimer disease may also be present. (from neurology 1997;48:376-380; neurology 1996;47:1113-1124)

Patient EducationClinical

Lewy Body Dementia

Lewy body dementia (LBD) is one of the most common types of dementia in older adults. Dementia is a loss of mental functions that is severe enough to affect your daily life and activities. These functions include:

The full article covers:

  • What is Lewy body dementia (LBD)?
  • What are the types of Lewy body dementia (LBD)?
  • What causes Lewy body dementia (LBD)?
  • Who is at risk for Lewy body dementia (LBD)?
  • What are the symptoms of Lewy body dementia (LBD)?
  • How is Lewy body dementia (LBD) diagnosed?
  • What are the treatments for Lewy body dementia (LBD)?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G31.83 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
331.82 Dementia w Lewy bodies
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2022No changes
FY 2023RevisedCode revised
FY 2024–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G31.83Overview

Is G31.83 (Other specified degenerative diseases of nervous system) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report neurocognitive disorder with Lewy bodies on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What is the ICD-9 equivalent of G31.83?

Under the General Equivalence Mappings, neurocognitive disorder with Lewy bodies converts to ICD-9-CM 331.82 (dementia w Lewy bodies). The mapping is a direct match.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.