IMPORTANT NOTE: JAAPA CME activities consist of 2 articles. To obtain credit, you must also read
Attention-deficit/hyperactivity disorder: Helping families to achieve success; the post-test will include questions related to both articles. AAPA Fellow members should complete and submit the post-test on the AAPA Web site by going to
www.aapa.org and searching for keyword
JAAPA post-tests. All others may complete and submit the post-test online at no charge at
www.mycme.com. To obtain 1 hour of AAPA Category I CME credit, PAs must receive a score of 70% or better on each test taken.
KEY POINTS
■ With life expectancy improving and the size of the population older than 65 years increasing, dementia will be a growing public health problem in the United States.
■ The precise frequency of treatable dementia has been difficult to determine; one meta-analysis found that 9% of dementias appear to be potentially reversible. Consequently, a precise diagnosis of the type of dementia and its cause is essential.
■ A reasonable screening battery of tests for the initial evaluation of a demented patient includes CBC, chemistry panel including electrolytes, vitamin B12, thiamine, free T4, thyroid-stimulating hormone, and VDRL synchronous fluorescent treponemal antibody-absorption (FTA-ABS).
■ In addition, patients should have neuroimaging, preferably noncontrast CT or MRI.
According to the
Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR), dementia is defined as multiple cognitive deficits that include memory impairment and at least one of the following cognitive disturbances: aphasia, apraxia, agnosia, or a disturbance in executive functions. The cognitive impairment must be sufficiently severe to cause impairment in occupational or social functioning and must represent a decline from a previously higher level of functioning.
1
Dementia is age related. With life expectancy improving2 and the size of the population older than 65 years increasing from 37 million people in 2006 to an estimated 71.5 million by 2030, dementia will be a growing public health problem in the United States.3 With the increasing number of elderly and the increase in the number of patients with dementia, greater attention to identifying potentially treatable and/or reversible causes is essential.
The precise frequency of treatable dementia has been difficult to determine. A meta-analysis published in 2003 found that 9% of dementias appear to be potentially reversible.4 It is also important to distinguish between delirium and dementia if appropriate interventions are to be initiated. Delirium is characterized by an acute, fluctuating change in mental status. Patients with delirium exhibit a cluster of symptoms, cognitive impairment, disorientation, and reduced ability to focus or maintain attention. Symptoms associated with dementia are insidious.5 This article reviews the etiologies, workup, and treatment of common, recognized reversible dementias.
ETIOLOGIES
Thyroid disorders The thyroid hormones play an important role in the function of the brain. The CNS contains neuroregulators and neuromodulators.6 Although overt hypothyroidism is well-established as a common cause of reversible dementia and depression, evidence is increasing that subclinical hypothyroidism is associated with cognitive and behavior disturbances.7,8 This is particularly important to remember because dementia and hypothyroidism are common in the older patient. A history, physical examination, and testing to measure levels of thyroid-stimulating hormone (TSH) and free thyroxine (T4) are appropriate.
Thyroid replacement therapy with synthetic levothyroxine is the treatment of choice for hypothyroidism.8 Follow-up testing with a thyroid panel is recommended in 6 to 8 weeks. It may take up to 3 months for thyroid levels to normalize.
Vitamin B12 deficiency Common in the elderly,9 vitamin B12 deficiency can manifest with hematological changes, neurologic impairments, mood changes, and cognitive impairment.10-12 B12 is required for the synthesis of S-adenosylmethionine, the main methyl-donor in the CNS for reactions involving neurotransmitters.11 Cognitive impairment should compel a neurologic (or neuropsychological) evaluation and testing for serum B12 value.
Even low-normal values of vitamin B12 can cause a cognitive decline in the elderly. Other laboratory assays such as measures of serum homocysteine and methylmalonic acid can be used to diagnose B12 deficiency even when the serum B12 level is normal. Both homocysteine and methylmalonic acid levels will be elevated when B12 deficiency is present.13
The most common cause of B12 deficiency is malabsorption. Supplementation of vitamin B12 can be accomplished by the oral, nasal, or IM route. Most clinicians prefer the IM route, given that malabsorption is the most common cause. Treatment schedules for IM administration vary but usually involve initial loading doses followed by monthly maintenance injections. One regimen consists of injections of 1,000 mcg daily for 1 to 2 weeks, followed by a maintenance dosage of 1,000 mcg every 1 to 3 months.13 Recent studies have shown that high oral doses are as effective as IM treatment.14 The recommended oral dose is 2,000 mcg daily. Follow-up tests to measure vitamin B12 levels are necessary to ensure that replacement is adequate.
Depression The symptoms of this disorder frequently occur with dementia.15 Depression is characterized by sadness, negative thoughts, loss of interest, and disruptions in sleep, appetite, energy levels, and thinking. Depression is well-recognized to affect memory, attention, and cognitive function.16,17Pseudodementia is a term often applied to the cognitive impairment caused or exacerbated by depression. Some elderly persons are unaware of their mood state and may deny sadness and other typical symptoms of dysthymia. Thus clinicians must be doubly alert to recognize sadness, anxiety, and vegetative symptoms and signs to detect depression. The older patient presenting with depression should be fully evaluated for dementia.
Both pharmacologic and nonpharmacologic approaches to treating depression are helpful in reducing depressive symptoms in cognitive impairment and dementia. Antidepressants are frequently prescribed. The choice of agent is based on adverse effect profile and the characteristics of the individual patient. Selective serotonin reuptake inhibitors (for example, sertraline) may be preferred because they appear to be better tolerated than other antidepressants. Venlafaxine, bupropion, and mirtazapine may also be effective. Agents with substantial anticholinergic effects (such as amitriptyline) should be avoided. A trial of an antidepressant should include an adequate dosage and duration—8 to 12 weeks of treatment with at least 4 weeks at an adequate dosage. Treatment should continue until the patient not only responds but reaches remission.18