http://cpmcnet.columbia.edu/news/frontiers/archives/biomed_v4n3_0005.html
Biomedical Frontiers: SPRING/SUMMER 1997, Vol.4, No.3
Special Section: Alzheimer's Research
Extrapyramidal Signs
Many patients with Alzheimer's disease experience not only the well-known
problems of memory loss, but also what are termed extrapyramidal signs.
These physical symptoms, which include tremors, rigidity, and slowness of
movement, resemble the symptoms of Parkinson's disease. In fact, in some
cases, patients with extrapyramidal symptoms do have Parkinson's disease. In
other cases, patients take neuroleptic medicines that cause the side
effects. However, in many instances, the cause of extrapyramidal signs in
patients with Alzheimer's disease is not clear.
In a study published in the March 1997 issue of the Annals of Neurology,
Drs. Yan Liu, Yaakov Stern, Michael Chun, Diane Jacobs, Patricia Yau, and
James Goldman found evidence that could help solve this puzzle. The
researchers first looked at clinical reports for Alzheimer's patients and
controls from CPMC. When they eliminated all cases in which a patient with
Alzheimer's also had Parkinson's disease or was on neuroleptic medications,
they still found 18 patients with Alzheimer's who also had extrapyramidal
symptoms.
The researchers used autopsies to confirm the findings in the Alzheimer's
cases, exploring sections of the substantia nigra and basal ganglia for
pathological changes, since pathology in these areas is known to produce a
variety of extrapyramidal signs. They found that degenerative changes in the
substantia nigra, especially neurofibrillary tangles, correlated with the
presence of extrapyramidal signs before death, says Dr. Liu, staff associate
in the pathology department's neuropathology division. However, the
researchers did not find a decrease in the total number of neurons in the
substantia nigra, as happens in Parkinson's disease and progressive
supranuclear palsy. "This indicates that extrapyramidal signs occur because
the neurons are somehow not functioning correctly," says Dr. Liu.