Dr. Marsel Mesulam responds:

Primary progressive aphasia (PPA) is caused by diseases that impair the function of nerve cells in language centers of the brain. In most right-handers, these centers are on the left side of the brain. The symptoms—which include impaired word-finding, spelling, and word comprehension—emerge very slowly. If the symptoms appear suddenly, other diagnoses should be considered.

In contrast to typical forms of Alzheimer's disease, patients with PPA may have intact memory for recent events and pursue complex activities of daily life. The memory problems are only related to language. PPA is usually caused by a disease called frontotemporal lobar degeneration, but in about 30 percent of patients, the cause may be an atypical form of Alzheimer's disease. This is why many doctors will prescribe drugs that are also used in Alzheimer's. Speech therapy may be useful for some patients. PPA has many different forms and it is crucial to individualize patient care.