Dementia

Dementia: Excerpt from The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter

Anne Cather Cutlip

Dementia is characterized by a progressive cognitive decline leading to social or occupational disability occurring in a state of clear consciousness. It has an age-dependent epidemiology, occurring in 8% of patients aged 65 years and older in the United States, progressing from 1% to 2% in patients aged 65 to 70 years to approximately 30% in patients aged 80 years and older (1).

Approach.

A common way to think about the dementias is to consider whether the dementia is either irreversible (90%) or reversible (10%). Among all dementias, Alzheimer’s dementia (AD) is by far the most common (50% to 60%). It has been well characterized by the insidious onset of memory loss followed by a decline of other cognitive functions. Personality is preserved.

The vascular dementias (VD), which include multiinfarct dementia and small vessel disease (lacunae), account for 20%. Patients with VD typically have a sudden onset and stepwise deterioration in the presence of cerebrovascular disease (by neurologic examination or imaging). The disease presents with gait disturbances, frequent falls, and personality or mood changes, often in patients with diabetes mellitus, hypertension, or hyperlipidemia. Another 15% of dementias have a coexistence of VD with AD.

 A. Irreversible causes include AD, VD, intracranial tumor, Pick’s disease (PD), Parkinson’s disease (30% develop dementia), alcoholism, Lewy body dementia (LBD), Huntington’s disease (HD), progressive supranuclear palsy (PSP), Creutzfeldt–Jakob disease (CJD), acquired immunodeficiency syndrome (AIDS), and some metabolic diseases (Gaucher’s disease, Niemann-Pick disease, metachromatic leukodystrophy). PD is characterized by socially inappropriate behavior, disinhibition with relatively preserved memory. LBD has features of parkinsonism, hallucinations and fluctuations in alertness and cognition. HD is an autosomal dominant disorder with depression, choreiform movements and dementia. PSP is a parkinsonlike syndrome with gaze paresis. CJD is a fatal viral infection with progressive mental deterioration, myoclonic jerks, blindness, and gait disturbance.

 B. Reversible causes. About half the cases are caused by depression or drugs and have a fair chance of total recovery. Metabolic disorders, the third most common category of reversible dementia, have less chance of a full recovery. Normal pressure hydrocephalus is the fourth most common cause (2). It should be suspected in the elderly who have dementia, gait disorder, and urinary incontinence. Other diagnoses to consider include psychiatric diagnoses (schizophrenia, malingering), drugs or toxins (alcohol, mercury, lead, lithium), and metabolic conditions (renal disease, hypo- or hyperglycemia, hypo- or hyperthyroidism, hepatic encephalopathy, hyperparathyroidism, Cushing’s disease, Wilson’s disease, and acute intermittent porphyria). Other common causes include infection (urinary tract infection, pneumonia), anoxia (congestive heart failure, chronic obstructive pulmonary disease, anemia), vitamin deficiency (B ₁₂, folic acid, thiamine, niacin), trauma (subdural hematoma, concussion), vascular (ischemic or hemorrhagic stroke), and central nervous system (CNS) infection (syphilis, abscess, chronic meningitis) (3).

History.

A concerned family member will often bring patients into the office when obvious memory impairment occurs. The deficit will be sufficiently obvious to interfere with daily living, work, or social activities. When questioning the reliable historian, ask about the specific cognitive changes (language, judgment, abstract thinking, praxis, visual recognition, and constructional ability). Ask about the duration of symptoms, the mode of onset (insidious or abrupt), and the progression (slow or rapid, gradual or stepwise). Check on general risk factors (e.g., increasing age, atherosclerosis, head trauma, CNS infection), and family history. Specific risk factors for AD include increasing age, lower intelligence, small head size, history of head trauma (4), and Down’s syndrome.

Physical examination.

The patient should undergo a thorough general and neurologic examination and Mini-Mental Status Examination (MMSE). Look for focal neurologic deficits and assess cognitive function (memory, language, perception, praxis, attention, judgment, calculation and visuospatial function). Other neuropsychiatric testing is available.

Testing

 A. Clinical laboratory tests. The major value in laboratory tests is to look for potentially treatable causes of dementia. Basic tests should include complete blood count, electrolytes, basic chemistry (glucose, calcium, lipid panel), liver and thyroid function tests, vitamin B₁₂, folate, urinalysis, erythrocyte sedimentation rate, and serologic test for syphilis. In addition, if the history indicates, consider human immunodeficieny virus (HIV) testing as well as heavy metals and toxic screens.

 B. Diagnostic imaging. Computerized tomography is usually sufficient to rule out surgical (subdural hematoma, normal pressure hydrocephalus, tumor) and most cerebrovascular causes of dementia. Although more expensive, magnetic resonance imaging is superior to visualize small lacunae and temporal lobe atrophy (2). Positive emission tomography scanning is very expensive and seems to have greater resolution and sensitivity, but for now seems to be more of a research tool.

C. Other testing. Electroencephalography generally shows nonspecific changes except in cases of seizures, CJD, and hepatic encephalopathy. The MMSE, which is a widely used, simple tool that requires less than 10 minutes to perform, enables assessment of cognitive function (Chapter 4.5). Expected results somewhat depend on the patient’s educational level.

Diagnostic assessment.

The differential diagnosis in dementia most commonly includes age-associated memory impairment (AAMI), delirium, depression, schizophrenia, chronic alcoholism, and mental retardation. AAMI is a normal aging process with gradual memory loss in absence of dementia or medical conditions. Delirium has a subacute onset with hallucinations, delusions, and psychomotor agitation (Chapter 4.3). Common causes include infection (urinary tract infection, pneumonia), electrolyte imbalance, hypoglycemia, hepatic or renal dysfunction, endocrine abnormalities (thyroid), and medications or toxins (anticholinergics, benzodiazepines, narcotics).

References

1. Richards SS, Hendrie HC. Diagnosis, management, and treatment of Alzheimer dementia. Arch Intern Med 1999;159:789–798.

2. Crevel HV, van Gool WA, Walstra GJM. Early diagnosis of dementia: which tests are indicated? What are their costs? J Neurol 1999;246:73–78.

3. Weiner MF, ed. The dementias, diagnosis, management and research, 2nd ed. Washington, DC: American Psychiatric Press, Inc., 1996.

4. Kaye JA. Diagnostic challenges in dementia. Neurology 1998;51(Suppl):S45–S52.

Book Source Details

• Book Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter
• Author(s): Robert B. Taylor (editor)
• Year of Publication: 2000
• Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2000 Lippincott Williams & Wilkins.

More About Delirium tremens

• Back to disease: Delirium tremens: Introduction
• Next Book Extract About Delirium tremens: Dementia (Field Guide to Bedside Diagnosis)
• More Book Extracts: All Online Books for Delirium tremens

More Medical Textbooks Online about Delirium tremens

Review other book chapters online related to Delirium tremens:

Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter Authors: Robert B. Taylor (editor) Publisher: Lippincott Williams & Wilkins Copyright: 2000 ISBN: 0-78172-094-X

 » Next page: Dementia (Field Guide to Bedside Diagnosis)

Rate This Website

What do you think about the features of this website? Take our user survey and have your say:

Website User Survey

Medical Tools & Articles:

Next articles:

• Dementia (Field Guide to Bedside Diagnosis)
• Delirium/Hallucinations (Field Guide to Bedside Diagnosis)
• Level of consciousness, decreased (Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series)
• Level of consciousness, decreased (Signs & Symptoms: A 2-in-1 Reference for Nurses)
• Agitation (Signs & Symptoms: A 2-in-1 Reference for Nurses)

Tools & Services:

• Bookmark this page
• Symptom Search
• Symptom Checker
• Medical Dictionary
• Give your feedback

Medical Articles:

• Disease & Treatments Search
• Misdiagnosis Center
• Full list of interesting articles

Forums & Message Boards

• Ask or answer a question at the Boards:
• I cannot get a diagnosis. Please help.
• Tell us your medical story.
• Share your misdiagnosis story.
• What is the best treatment for my condition?
• See all the Boards.

Enter your search terms Submit search form
Search The Web Search wrongdiagnosis.com

Common Health Mistakes

Symptom
Checker

Search Specialists by State and City