P&S Journal: Winter 1998, Vol.18, No.1
When Alzheimer's Gets Physical
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, P&S researchers found evidence that could help solve this puzzle.
Drs. Yan Liu, Yaakov Stern, Michael Chun, Diane Jacobs, Patricia Yau, and James Goldman first looked at clinical reports for Alzheimer's patients and controls and eliminated all cases in which a patient with Alzheimer's also had Parkinson's disease or was on neuroleptic medications. In the 18 remaining patients with Alzheimer's and extrapyramidal symptoms, the researchers used autopsies to explore 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 neuropathology. 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.