The other types of dementia
by E. David Kirk, MD for The Wichita Eagle:
Dementia is defined as cognitive abnormality with functional impairment. When there is a cognitive abnormality without functional impairment, it is defined as mild cognitive impairment, or MCI.
About 30 years ago, it was believed that people with dementia all had cerebral vascular disease and strokes. We now know that several diseases other than Alzheimer’s disease cause significant cognitive impairment. There are similarities of these diseases but also distinguishing features that can differentiate them. An accurate diagnosis is important for treatment and future planning.
Vascular dementia accounts for about 20 percent of dementia illnesses and is the second most common. Vascular dementia is often an abrupt onset in contrast to Alzheimer’s, which has a slow onset and progression. Symptoms of vascular dementia may be intermittent. Risk factors include hypertension, diabetes, cerebral vascular disease and hyperlipidemia (high cholesterol and triglyceride levels). There may be neurological abnormalities and a CT scan of the head may show evidence of a stroke. In some cases, Alzheimer’s cannot be differentiated from vascular dementia, and that is termed Alzheimer’s with cerebral vascular features or a mixed dementia.
Vascular dementia accounts for about 20 percent of dementia illnesses and is the second most common. Vascular dementia is often an abrupt onset in contrast to Alzheimer’s, which has a slow onset and progression. Symptoms of vascular dementia may be intermittent. Risk factors include hypertension, diabetes, cerebral vascular disease and hyperlipidemia (high cholesterol and triglyceride levels). There may be neurological abnormalities and a CT scan of the head may show evidence of a stroke. In some cases, Alzheimer’s cannot be differentiated from vascular dementia, and that is termed Alzheimer’s with cerebral vascular features or a mixed dementia.
In general, any patient with a gait or neurologic abnormality, before age 65, should be suspected of having a non-Alzheimer’s dementia.
Dementia with Lewy bodies is the third most common. There is progressive loss of cognition but fluctuating episodes in contrast to Alzheimer’s. Hallucinations are prominent and the family often reports that the patient has excessive sleepiness. The patient has Parkinson’s disease features but the dementia precedes the Parkinson’s disease peripheral abnormalities. About 50 percent of patients with Parkinson’s will develop dementia after about five years. But unlike Lewy body dementia, Parkinson’s precedes the dementia. The FDA has approved the cholinesterase inhibitor Exelon for treatment.
Normal pressure hydrocephalus has a classic trait of gait abnormality, urinary incontinence and cognitive impairment. There is a structural brain abnormality with enlarged ventricles due to excess cerebral spinal fluid caused by a reabsorption defect. Surgery can relieve the hydrocephalus but often is not successful.
Progressive supranuclear palsy is characterized by early prominent problems with gait, balance and falls. The hallmarks are paralysis of upward gaze and body rigidity. Cognitive abnormalities eventually develop. Catecholaminergic drugs have been used for treatment, but there is no evidence that it really helps.
Peck’s disease (front temporal dementia) develops before age 65. The most prominent symptom is behavior abnormality and many patients are diagnosed with psychiatric conditions. There is no approved medication for the cognitive abnormality, but antipsychotic medications are often prescribed.
Primary progressive aphasia is a form of cognitive impairment that involves a progressive loss of language function with eventual cognitive abnormalities. There are currently no FDA-approved therapies.
Other courses of dementia include head trauma, drugs such as alcohol, brain tumors, thyroid disease, delirium and malignancies. Memory loss may be due to depression, and that is termed pseudo dementia. A specific diagnosis is initiated for patient prognosis and family planning.
One last caveat – any complaint of memory loss or cognitive abnormality should not be accepted simply as advanced age.
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