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Dementia is a loss of brain function over weeks, months, or years that occurs with certain diseases.  

Dementia due to metabolic causes is a loss of brain function that can occur with diabetes, thyroid disease, and other metabolic disorders. The term "metabolic" refers to the physical and chemical processes in the body.

Metabolic causes of dementia include:

• Endocrine disorders, such as Addison's disease or Cushing's disease
• Heavy metal exposure, such as to lead, arsenic, mercury, or manganese
• Repeat episodes of low blood sugar (hypoglycemia), most often seen in people with diabetes who use insulin
• Hyperparathyroidism, which is very high levels of calcium in the blood
• Hypothyroidism (low levels of thyroid hormone) or thyrotoxicosis (very high levels of thyroid hormone in the body)
• Liver cirrhosis
• Porphyria
• Nutritional disorders, such as vitamin B1 deficiency, vitamin B12 deficiency, pellagra, or protein-calorie malnutrition

Dementia that occurs with metabolic disorders may cause confusion and changes in thinking or reasoning. These changes may be short-term or lasting. Dementia symptoms can be different for everyone. They depend on the health condition causing the dementia.

The early symptoms of dementia can include:

• Difficulty performing tasks that used to come easily, such as balancing a checkbook, playing games (such as bridge), and learning new information or routines
• Getting lost on familiar routes
• Language problems, such as having trouble finding the name of familiar objects
• Losing interest in things you previously enjoyed, flat mood
• Misplacing items
• Personality changes and loss of social skills

As the dementia get worse, symptoms are more obvious and interfere with the ability to take care of yourself:

• Changing sleep patterns, often waking up at night
• Forgetting details about current events, forgetting events in one's life history
• Having difficulty doing basic tasks, such as preparing meals, choosing proper clothing, or driving
• Having hallucinations, arguments, striking out, and behaving violently
• Having more difficulty reading or writing
• Using poor judgment and losing the ability to recognize danger
• Using the wrong word, not pronouncing words correctly, speaking in confusing sentences
• Withdrawing from social contact

Note: The person may also have symptoms from the disorder that caused dementia.

An examination of the nervous system (neurologic examination) can show different problems, depending on the cause. Abnormal reflexes may be present.

Tests to diagnose a medical condition causing the dementia may include:

• Ammonia level in the blood
• Blood chemistry, electrolytes
• Blood glucose level
• BUN, creatinine to check kidney function
• Liver function tests
• Lumbar puncture (spinal tap)
• Nutritional assessment
• Thyroid function tests
• Urinalysis
• Vitamin B12 level

To rule out certain brain disorders, a head CT scan or head MRI scan is usually done.

Treatment focuses on managing the disorder and controlling symptoms.

Medications used to treat Alzheimer's disease have not been shown to work for this type of dementia. However, sometimes these drugs are used anyway, when other treatments are unable to control the underlying problems.

See: Dementia - home care for information about taking care of a loved one with dementia.

The outcome varies depending on the cause of the dementia and the amount of damage to the brain.

Complications may include the following:

• Loss of ability to function or care for self
• Loss of ability to interact
• Pneumonia, urinary tract infections, and skin infections
• Pressure sores
• Symptoms of the underlying problem (such as loss of sensation due to a nerve injury in vitamin B12 deficiency)

Call for an appointment if symptoms get worse or continue. Go to the emergency room or call the local emergency number (such as 911) if there is a sudden change in mental status or a life-threatening emergency.

Treating the metabolic disorder may reduce the risk of developing this type of dementia.

DeKosky ST, Kaufer DI, Hamilton RL, Wolk DA, Lopez OL. The dementias. In: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth-Heinemann; 2008:chap 70.

Brewer JB, Gabrieli JDE, Preston AR, Vaidya CJ, Rosen AC. Memory. In: Goetz CG, ed. Textbook of Clinical Neurology. 3rd ed. Philadelphia, Pa: Saunders;2007: chap 5.

Metabolic Syndrome and Risk of Dementia in Older Adults. Journal of the American Geriatrics Society 2010; 58(3):487-492.