Platelets enter into Alzheimer's disease.
Several years ago, scientists found that Alzheimer's patients with excess fluid in the surface membranes of their blood platelets develop symptoms earlier -- in their mid-60s and early 70s -- and suffer more debilitating effects than Alzheimer's patients without the platelet abnormality. The researchers, at the University of Pittsburgh, also found increased platelet-membrane fluid in about half the parents and sibligns of Alzheimer's patients with the biological defect (SN: 11/7/87, p.301).
The same group now reports in the October ARCHIVES OF GENERAL PSYCHIATRY that parents and siblings of Alzheimer's patients with elevated platelet-membrane fluidity who develop symptoms of Alzheimer's disease do so significantly earlier -- again in their 60s and early 70s -- than relatives of patients with normal platelet-membrane fluidity.
The average age at which the first Alzheimer's symptoms appeared for relatives of patients with increased platelet-membrane fluidity was more than five years younger than for relatives of patients without the potential biological marker.
The finding further supports the notion that there is more than one form of Alzheimer's disease, write psychiatrist Gary W. Small and biomathematician David A. Greenberg of the University of California, Los Angeles, in an accompanying editorial. They say it is also consistent with the hypothesis that multiple genes, possibly including one or more coding for platelet-membrane fluidity, increase a person's risk for Alzheimer's disease.
A biological marker may have little or nothing to do with the causes of a disease, Small and Greenberg caution, although platelet abnormalities could indicate alzheimer's is a metabolic disease extending well beyond the brain.
"Costly and time-consuming" prospective studies of relatives of Alzheimer's patients are necessary to learn which participants with elevated platelet-membrane fluidity will develop the disease, add the Los Angeles researchers. The strength of the biological measure as a diagnostic tool is still unclear.
The Pittsburgh study, directed by psychiatrist George S. Zubenko, concentrated on 421 parents and siblings of 43 Alzheimer's patients and of 47 healthy controls. Family members and others who knew each participant well answered a standardized questionnaire designed to distinguish between symptoms of Alzheimer's disease and other disorders, such as stroke, alcoholism and Parkinson's disease.
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|Date:||Oct 29, 1988|
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