Dementia is not always due to Alzheimer disease. An accurate diagnosis is important, as the various causative conditions can differ in their course and treatment.
Dementia refers to cognitive impairment severe enough to interfere with the ability to independently perform activities of daily living. It can occur at any age but is most common after age 60. Some studies estimate that 13.9% of people age 71 and older have some form of dementia.1 The prevalence increases with age, ranging from 5% at age 70 to 79 to 37% at age 90 and older.1
Alzheimer disease accounts for about 60% to 80% of cases,2 or an estimated 4.7 million people age 65 and older in the United States, a number anticipated to climb to 13.8 million by 2050.3
Other types of dementia are less often considered and are challenging to recognize, although many have distinct characteristics. This article summarizes the features and management of the more common non-Alzheimer dementias:
- Vascular dementia
- Dementia with Lewy bodies
- Progressive supranuclear palsy
- Corticobasal degeneration
- Multiple system atrophy
- Parkinson disease dementia
- Frontotemporal dementia
- Primary progressive aphasia
- Normal-pressure hydrocephalus
- Rapidly progressive dementia (ie, Creutzfeld-Jakob disease, autoimmune disease).
After Alzheimer disease, vascular dementia is the most common dementia, accounting for about 20% to 30% of cases. Clinical criteria have not been widely accepted, although several have been published, including those in the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) and the National Institute of Neurological and Communicative Diseases and Stroke-Association Internationale pour la Recherche et l’Enseignement en Neurosciences.
Risk factors for vascular dementia include cerebrovascular disease (hypertension, diabetes, hyperlipidemia) and coexisting conditions related to atherosclerosis (coronary artery disease, peripheral artery disease).
The Hachinski Ischemic Score is a good bedside tool to help differentiate Alzheimer dementia from vascular dementia.5
Sudden onset and stepwise decline
Vascular dementia often presents as a sudden and stepwise progression of cognitive deficits that stabilize and that are caused by vascular insults (Table 1).6–10 Some patients have continuous decline after a vascular event, indicating that Alzheimer dementia may also be present. Dementia is then defined as a mixed type.
Behavioral problems such as physical aggression, hallucinations, paranoia, and mood fluctuations are common.11
Deficits depend on vascular areas affected
Cognitive deficits are heterogeneous and are often related to the location of the vascular insult. Involvement of subcortical areas may result in executive dysfunction, slowed processing speed, and behavioral changes.12
Executive dysfunction may be identified using the Trail Making Test (Part B) or the Executive Interview (EXIT25). Office-based tools such as the Folstein Mini-Mental State Examination, the Montreal Cognitive Assessment, or the St. Louis University Mental Status Examination may also uncover these deficits.
Focal neurologic deficits may be found on clinical examination.
Structural neuroimaging may identify small strokes in areas of the brain affecting cognitive function or occlusion of a larger vessel associated with more profound neurologic deficits. Neuroimaging findings may not correlate with any significant decline noted by the patient, suggesting “silent” strokes.
Treat symptoms and manage risk factors
Although the US Food and Drug Administration (FDA) has not approved any pharmacotherapy for vascular dementia, commonly prescribed cognitive enhancers have demonstrated some benefit.13
Behavioral problems such as aggression can be disturbing to the patient and the caregiver. Nonpharmacologic methods (eg, redirection, rescheduling care activities to avoid conflict, avoiding issues that lead to agitation) should be tried first to address these problems.
Drug therapy may be used off-label for neuropsychiatric symptoms such as hallucinations, delusions, and combativeness, but clinical trials of these agents for this purpose have shown mixed results,14 and their use is often associated with significant risk.15 Antipsychotic drugs are associated with a risk of death and pneumonia when prescribed for dementia. Many also carry a risk of QT prolongation, which is particularly concerning for patients with coronary artery disease or rhythm disturbances.
The key to reducing further decline is to optimize management of vascular risk factors to reduce stroke risk.