Conquering the Confusion of Dementia Coding

Dementia is a common secondary diagnosis; often coders will quickly assign a “memorized” code for it and move on. However due to its commonality, are we missing something such as a co-morbid or complication code that could influence reimbursement? Or are we over-coding symptoms that are inherent to the dementia disease process?

This casual code assignment is complicated by the fact that, often, documentation related to dementia does not present a clear picture of the neurological symptoms related to dementia or those that are a result of other general medical conditions.

In this article, we will review the different codes listed in ICD-9-CM for dementia and some characteristics of each type of dementia. We will also discuss specific instructional notes associated with the dementia codes and determine when it is necessary to seek physician clarification.

Causes & Symptoms of Dementia

Dementia is not a specific disease but rather a group of symptoms related to a decrease in cognitive and social abilities that eventually interfere with a person’s cognitive efforts in work performance, relationships and social activities. These symptoms are a result of dysfunction in the cerebral cortex or other brain tissue. Dementia usually occurs in people over age 60.

Patients with dementia will develop cognitive impairments in areas of language, reasoning, judgment and problem-solving abilities. Forgetfulness, depression and clumsiness are common in early symptoms of dementia. As the condition progresses, patients often experience agitation triggered by their confusion and frustration, and they may become hostile. In later stages, behavioral disturbances, such as wandering off, physical violence and perversion, may become the most challenging issue for caretakers to handle.

To support a diagnosis of dementia, two or more brain functions must be impaired, according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM IV). Alzheimer’s disease is the most common cause of dementia, but not the only cause. A wide variety of physiological conditions, such as alcohol and substance use, and medication reactions are all known causes leading to dementia.

In instances where dementia exists due to conditions such as traumatic or anoxic brain injury or a history of substance abuse with abstinence, dementia can be a static condition. In other cases where dementia is a manifestation of another disease process (i.e., normal pressure hydrocephalus, diabetes), proper control of the physiological condition may slow or arrest the progression of vascular dementia. Dementia associated with neurodegenerative diseases (i.e., AIDS, Lewy bodies and multiple sclerosis), is progressive and permanent. In some cases, the exact reason some patients develop dementia is not yet understood. One source lists 394 conditions associated with dementia.

Dementia Types & ICD-9 Coding

Now, we will look at how ICD-9 classifies dementia and review some of the associated instructional notes for code selection.

ICD-9-CM classifies dementia into the following subcategories:


Senile dementia, uncomplicated, NOS


Presenile dementia


Senile dementia with delusional or depressive features


Senile dementia with delirium


Vascular dementia


Drug-induced persisting dementia


Dementia in conditions classified elsewhere, with/without behavioral disturbances


Dementia, unspecified, with/without behavioral disturbances


Frontotemporal dementia


Dementia with Lewy bodies

Senile & Presenile Dementia (290.0 – 290.3)

Senile dementia occurs after age 65. A diagnosis of dementia with onset prior to age 65 is presenile dementia. Although some decline in cognition and mental capacity is normal as we age, dementia is not a normal part of aging.

As always, coders should look to physician documentation to determine the type of dementia. Senile and presenile are archaic terms, not often seen in current documentation. If the physician has not stated “senile” dementia, it would be incorrect to select a code for senile dementia, simply because the patient is over age 65.

Vascular Dementia (290.40 – 290.43)

Vascular dementia is the second most common type of dementia. Incidences increase with advancing age. A buildup of plaque (atherosclerosis), amyloid protein and other debris circulating in the blood stream causes damage to the cerebrovascular system leading to vascular dementia. Multi-infarct dementia is one type of vascular dementia and develops because multiple mini-infarctions occur, scattered throughout the brain. As new, undetectable infarcts occur, symptoms of impairment associated with the affected area of the brain may change suddenly.

Ex: An 87-year-old male with a history of atherosclerosis presents with sudden onset of confusion and agitation. Workup reveals no infectious processes, labs WNL. Patient near baseline. Discharge Diagnosis: Multi-infarct dementia due to atherosclerosis, suspected mini stroke.

  • 434.91 Cerebral artery occlusion, unspecified
  • 290.43 Vascular dementia with delirium
  • 437.0 Cerebral atherosclerosis

Review the instructional note under subcategory code 290.4, “use additional code to identify cerebral atherosclerosis (437.0).” This note applies to all codes in subcategory 290.40-290.43. The following excludes note, under the use additional code note, provides direction on what code to assign for vascular dementia with “no clear evidence of arteriosclerosis” (290.9).

Dementia With Lewy bodies (331.82)

Lewy bodies are abnormal microscopic deposits of protein that settle in the brain and destroy nerve cells. Typical Parkinson’s type symptoms develop, such as tremors, muscle rigidity and dementia. These patients may also experience delusions and depression.

Review the instructional note at category 332 Parkinson’s disease, which excludes code 331.82 Parkinson’s with Lewy bodies. Lewy bodies with Parkinsonism is a more specific diagnosis than just Parkinson’s disease, per Coding Guidelines, assign the code for the most specific diagnosis.

When physician documentation lists Lewy bodies with Parkinson’s disease, the ICD-9 codebook instructional note directs coders to assign code 331.82 Dementia with Lewy bodies, plus an additional code to identify with or without behavioral disturbances (294.10-294.11).

Delirium, Delusional & Depressive Features

ICD-9-CM provides combination codes to identify specific types of dementia with delirium, delusional and depressive features. These codes are CCs that may affect the MS-DRG and reimbursement.

Delirium is a sudden on-set transient bout of altered consciousness and change in cognition most often attributed to a direct physiological condition. Delirium is often confused with dementia; however, delirium dissipates when the underlying general medical condition resolves, dementia is typically irreversible.

Seek clarification from the physician if documentation does not identify the type of dementia and clarify the underlying cause of acute delirium. If the cause of the delirium or type of dementia is unknown, code the conditions separately.

Delusional features are present in many psychiatric disorders including Alzheimer’s disease, personality and mood disorders. Delusions are irrational, unwavering beliefs that are clearly false and have no logical or normal basis of reasoning.

ICD-9-CM classifies the diagnosis of delusional disorders to category 297, in the Mood Disorder section. A Delusional disorder is not the same as a delusional feature.

Depressive features and depressive mood. Depression is an inherent part of the dementia disease process.

When documentation lists dementia and depression separately, without further documentation to indicate the depression is related to dementia, code them separately.

Behavioral Disturbances

Simply stated, a behavioral disturbance is any behavior that puts the patient or others at risk.

Not all patients with dementia have behavioral disturbances, but as the individual ages and dementia progresses, the likelihood increases of behavior problems manifesting and becoming the more challenging aspect of patient care.

Noted under many of the dementia codes is the instructional note “use additional code to identify behavioral disturbances.” You will also find listed under the behavioral disturbance codes, subcategory code 294.1x, the instructional note, “code first underlying physical condition.” These two notes provide code sequence instruction, directing the underlying condition to be sequenced before the 294.1x code.


Dementia in conditions classified elsewhere without behavioral disturbances


Dementia in conditions classified elsewhere with behavioral disturbances

Ex: An 87-year-old nursing home patient with Alzheimer’s dementia has repeatedly wandered off.

  • 331.0 Alzheimer’s disease
  • 294.11 Dementia in conditions classified elsewhere with behavioral disturbance
  • V40.31 Wandering in diseases classified elsewhere

Behavior disturbances include a wide array of disruptive behavior. It is the coder’s responsibility to watch for documentation that identifies this type of behavior. Physician documentation may not always specifically state “with behavioral disturbances.” If in doubt, query the physician for clarification.


In this article, we have reviewed the most common types and characteristics of dementia coded in ICD-9 and looked at many of the associated coding conventions. Documentation on dementia as a chronic, pre-existing condition can be vague and disconnected from other neurological traits the patient may have, making it difficult for the coder to select the most accurate code. As always, when documentation is not clear, query the physician for clarification.

Danita Arrowood is anAHIMA -approved ICD-10-CM/PCS trainer and an educator/medical coding educator with Precyse (, which provides services and technologies that capture, organize, secure and analyze healthcare data and transform it into actionable information, supporting the delivery of quality patient care and optimizing operating performance. Danita develops content materials for ICD-9-CM and ICD-10-CM/PCS and provides clinical documentation improvement education. Danita is also adjunct faculty at Phoenix Community College.

Test your knowledge on page 2.


1. When dementia is unspecified, use the code for presenile or senile dementia, depending on the patient’s age at on set.

a. True
b. False

2. A 47-year-old, HIV-positive male patient was admitted following an aggressive outburst at the nursing home. The patient became combative and tried to bite his caregiver. Admitting diagnosis: Decompensated dementia secondary to HIV.

a. 042, 294.10
b. 042, 294.11
c. 042, 294.21
d. 294.21, 042

3. A 79-year-old woman was transfered from a SNF after she became delusional and found to have a low-grade fever. The work-up revealed E. coli-positive urine. She was started on Cipro and transferred back to the SNF. Discharge Dx: UTI with acute delirium, CHF and dementia. The correct codes would be:

a. 599.0, 293.0, 428.0, 294.20, 041.4
b. 599.0, 294.20, 428.0, 780.09, 04.14
c. 780.09, 599.0, 294.21, 428.0, 041.4
d. 599.0, 293.0, 294.20, 428.0, 041.4

4. A Patient presents with a change in mental status and new, onset aphasia with a CT scan finding of a new infarction in the MCA. PMH lists CAD, HTN and vascular dementia. The correct codes would be:

a. 434.91, 290.40, 414.01, 401.9
b. 434.91, 290.40, 437.0, 414.01, 401.9
c. 434.91, 290.40, 437.0, 414.01, 401.9, 784.3
d. 784.3, 434.91, 290.40, 437.0, 414.00, 401.9


1. False. The physician must identify the type of dementia to support a specific type of dementia code assignment.

2. B. Per Coding Guidelines, HIV is sequenced a principal diagnosis with the dementia with behavioral disturbances as secondary code. In the scenario, combativeness and biting identify behavioral disturbances.

3. D. Since the acute delirium was caused by the UTI, assign the acute delirium code as a secondary code. There is no indication of behaviors related to dementia, so assign the dementia without behavioral disturbances code.

4. C. The new onset aphasia and mental status change are due to the MCA infarction. Vascular dementia in the setting of atherosclerosis requires two codes, 290.4x and 437.0. Codes for the other documented conditions are listed as secondary codes.

About The Author