Dementia is a gradual, overall decline in the mental functions of a previously competent person resulting in the loss of ability to perform activities of daily living (ADL). Reasoning, judgment, memory, and decision-making become impaired.

The essential feature of the etiology of dementia is a direct pathophysiological consequence of a general medical or neurologic condition. Major classifications of causes of the disease are neurologic and general medical conditions.

• Neurologic Causes

  • Parkinson's Disease has an unknown cause, and dementia appears in 22 to 60% of cases.

  • Huntington's Disease is an inherited degenerative disorder transmitted by a single autosomal dominant gene. It is usually diagnosed in the patient's late 30s to early 40s. It may present with changes in behavior such as irritability, and depression followed by motor activities of choreoathetosis.

  • Pick's Disease is a less common form of dementia that affects the frontal or temporal lobe. Patients display noticeable apathy and poor personal hygiene. The condition is seen more commonly in women, usually manifesting itself between the ages of 50 and 60. Patients may display a change in personality, deterioration in social skills, decreased intensity of emotional expression, removal of inhibitions, and prominent language abnormalities. There may be either apathy or extreme agitation.

• General Medical Conditions

  • Endocrine Dementia is caused by a hyposecretion (under secretion) or a hypersecretion of a hormone. Some examples are hypothyroidism, hypercalcemia, and hypoglycemia. Nutritional deficiencies of Vitamin B12, thiamine, and niacin may influence the development of dementia. Structural lesions, such as brain tumors, are capable of causing dementia.

  • Substance-Induced Dementia is caused by the ingestion of drugs, alcohol, etc., and symptoms of dementia last beyond the normal duration of the intoxification or withdrawal.

The diagnostic criteria for all types of dementia are as follows:

• Multiple cognitive deficits manifested by both:

  • Memory impairment (inability to learn new information or recall what was previously learned)

  • one (or more) of the following cognitive disturbances:

    • aphasia

    • apraxia

    • agnosia

    • disturbance in executive functioning (i.e., planning, organizing, sequencing, abstracting)

• The cognitive deficits must cause significant impairment in social functioning and represent a change from previous functioning.

• The deficits do not occur during a delirium.

• There is evidence from the history, physical examination, or laboratory findings that the deficits are caused by the effects of either neurologic, general medical conditions (endocrine, metabolic, Pick's disease, brain tumor) or are substance induced.

One or more of the following tests may be indicated to evaluate the underlying etiology:

• Mental status test.

• Brain-computed tomography (CT)

• Magnetic resonance imaging (MRI)

• Complete blood count (CBC)

• Erythrocyte sedimentation rate (ESR)

• Test for syphilis (VDRL)

• Metabolic screen (SMA 12)

• Serum thyroid-stimulating hormone level (TSH)

• Vitamin B12 level

• Human immunodeficiency virus (HIV) testing

• Tests for substance abuse, alcohol or poison

• Electroencephalogram (EEG)

• Chest x-ray (CXR)

• Cerebrospinal fluid analysis (CSF)

Primary dementia treatment is symptomatic and supportive (see Diagnostic Code: 9310 Dementia of unknown etiology). For some secondary causes of dementia, i.e., brain tumor, subdural hematoma, removing the cause may restore function or prevent further loss of function. Inappropriate or excessive use of medications is one of the treatable types of dementia. The use of alcohol and some drugs can mimic Alzheimer's disease in the elderly. Depression is called pseudodementia and it can be treated. Some endocrine and metabolic diseases, such as hypothyroidism and Vitamin B12 deficiency, may cause dementia and are usually correctable. Other dementias, caused by chronic lung disease, chronic liver disease, or uremia, can be reversed when the primary condition is corrected.

In primary dementia, a cure is not available and care falls on the family. Legal, financial, and final wishes should be clarified before the patient is incapacitated.