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Ms. Wick is a senior clinical research pharmacist at the National Cancer Institute, National Institutes of Health, Bethesda, Maryland. The views expressed are those of the author and not those of any government agency.

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Mention dementia these days, and you are as likely to hear a memory joke as you are to see a fleeting look of fear. Four dementias are common: Alzheimer's disease (AD; now affecting approximately 4.5 million Americans^1-5), vascular dementia (VaD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FD).⁶ Irreversible and incurable, dementia can be almost impossible to categorize until autopsy; yet, earlier diagnosis is associated with better prognosis.^7-9

Some memory loss is normal. Age-associated Cognitive Impairment (AACI) (or, benign memory impairment) occurs in up to 39% of elders¹⁰; experiences include tip-of-the-tongue events (word-finding failures), slower learning or concentration, and mild forgetfulness.¹¹ AACI patients navigate daily activities satisfactorily, at times joking about their deficits.^6,12,13

Alzheimer's Dementia

AD progresses slowly. Patients often are aware of faltering short-term memory and hide it until later stages of AD. AD patients do not learn, and prompting is useless. Eventually, disorganized thinking and often psychotic mood and personality disorders incapacitate patients.¹ Most AD patients live <8 years after diagnosis; comorbidities shorten survival.¹⁴

Vascular Dementia

Once called multi-infarct dementia, VaD's risk factors include hypertension, diabetes, arterial disease, and smoking.^15-17 VaD patients are acutely aware of their deficits and learn, but they may recall material only after hints. VaD impairment plateaus until another cerebral accident. Gait disorders, depression, apathy, and mood and behavioral changes are common. ^15,18-20 To prevent VaD, clinicians use antiplatelet therapy, control hypertension, and address risk factors.²⁰

Frontotemporal Dementia

FD (or, Pick's disease) causes behavioral changes and language problems in adults aged 35 to 75.^21,22 Disinhibited and socially inappropriate, FD patients often lack empathy and develop poor hygiene.²¹ Compulsive behaviors can be self-destructive (eg, exiting a moving vehicle) or criminal (eg, theft), reading and writing skills erode, and some patients become mute in as little as 2 years.²³ FD is untreatable; therefore, management targets agitation and behavior.²¹

Dementia with Lewy Bodies

Fifteen percent to 25% of dementia patients have DLB²⁴; severe dopaminergic loss causes bradykinesia, difficulty executing fine motor skills, masked face, stooped posture, and shuffling that looks like Parkinson's disease (PD) but less severe.²⁵ Because DLB's symptoms fluctuate widely hourly and daily, others may suspect that DLB patients are "faking it."

Vivid (but not frightening) visual hallucinations often occur during serious confusion.²⁶ Capgras syndrome—believing a significant other is an imposter—is common, as well as apathy, depression, slowed thought processes, getting lost easily, insomnia, autonomic dysfunction, and losing one's thought midsentence.²⁵ In almost half of DLB patients, neuroleptic exposure worsens the PD-like symptoms, increases cognitive deficits and hallucinations, and can cause life-threatening neuroleptic malignant syndrome.^26-28

Conclusion

Between 20% and 50% of dementia patients have mixed dementias.^16,29 Clinicians treat mixed-dementia patients empirically. Currently, several drugs are available to treat dementia; none are curative or more than satisfactory in their effects. Most patients with dementia end life in an institution. Perhaps this will not always be the case.

Table

References

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2. Hebert LE, Scherr PA, Bienias,JL, Bennett DA, Evans DA. Alzheimer disease in the US population: prevalence estimates using the 2000 census. Arch Neurol. 2003;60:1119-1122.
3. Evans DA, Funkenstein HH, Albert MS, et al. Prevalence of Alzheimer's disease in a community population of older persons. Higher than previously reported. JAMA. 1989;262:2551-2256.
4. Larson EB, Shadlen MF, Wang L, et al. Survival after initial diagnosis of Alzheimer disease. Ann Intern Med. 2004;140:501-509.
5. Alzheimer's Association. Statistics about Alzheimer's Disease. www.alz.org/AboutAD/statistics.asp. Accessed November 6, 2007.
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25. Bradley BF. Dementia with Lewy Bodies. In: Dementia. Continuum: Lifelong Learning in Neurology. 2004;10:81-112.
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