The Lyme Disease Network
Conference Abstract


Title:Lyme Disease vs. Depression vs. Somatization: Cognitive Tests & Functional Imaging
Authors:Fallon BA; Keilp J; Prohovnik I; Mann J
Conference:9th Annual International Scientific Conference on Lyme Disease & Other Tick-Borne Disorders, Westin Copley Plaza Hotel, Boston, MA, April 19-20, 1996
Presenter:Brian A. Fallon, M.D.
Assistant Professor of Clinical Psychiatry
Columbia University/NYS Psychiatric Institute

Abstract:
Not infrequently physicians are faced with the task of differentiating persistent Lyme disease (LD) from Somatization and Depression. This becomes most difficult when serologies are equivocal or negative. Given the possibility of placebo response to antibiotics, it behooves clinicians to make use of objective tools that may aid in differential diagnosis.

The use of neuropsychological tests to differentiate Lyme-related vs. depression-related cognitive problems will be discussed, focusing on tests of memory (Selective Reminding test/ Wechsler Memory test), attention (Digit Span), visual motor performance and tracking (Digit Symbol Modalities), and verbal fluency (Controlled Oral Word Association test).

Functional imaging (SPECT) differs from structural imaging (MRI, CT) in that SPECT gives high resolution images of the localized cerebral flow and neurochemical activity of the brain whereas routine MRI provides a static image of the anatomy of the brain. The application of SPECT imaging to neuropsychiatry and to Lyme disease in particular will be addressed, emphasizing patterns typical of depression vs. Lyme encephalopathy.

This talk will conclude by describing a controlled study of function brain imaging using Xenon 133 Regional Cerebral Flow (RCBF) among Lyme patients with complaints of persistent memory problems despite antibiotic treatment. The RCBF of 11 Lyme patients was contrasted with the RCBF of 22 age- and sex-matched normal controls. Analysis of individual normalized detector values revealed significant differences at three sites in the left hemisphere. Patients had lower relative flows at the inferior, posterior parietal detector and higher relative flows at the superior peri-rolandic detector and on the most posterior detector in the occipital lobe. The pattern at these detector sites is characteristic of Alzheimer's disease. The implications of these findings will be discussed. Further research is needed.

Unique ID: 96LDF022


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