Faculty Bibliography

OBJECTIVE: The goal of this study was to more precisely define the nature of the cognitive processing deficits in the patients with Lyme disease. BACKGROUND: Lyme disease has been associated with cognitive disturbances. METHOD: Sixteen patients who met the Centers for Disease Control's case definition for Lyme disease and 15 age- and education-matched control subjects completed two computerized assessments. The first was a matching procedure that assessed perceptual/motor speed. The second task was an alphabet-arithmetic (AA) test that measured the speed of mental arithmetic. On the matching task, subjects judged as true or false simple identity equations (e.g., B + 0 = B). On the AA task, subjects indicated the veracity of equations of the same form as those of the matching task but which required mental arithmetic (e.g., A + 3 = D). The use of this paradigm permits sensory or motor slowing to be distinguished from slowed cognitive processing speed. Also, the tests do not involve automated or overlearned responses. RESULTS: Lyme disease patients and healthy controls did not differ in perceptual/motor speed. However, Lyme disease patients' response times were significantly longer than those of healthy controls during the AA task, demonstrating specific impairments in mental activation speed. CONCLUSIONS: These results suggest that Lyme disease patients show specific deficits when initiating a cognitive process. These impairments are independent of sensory, perceptual, or motor deficits.

The neuropsychiatric sequelae of chronic Lyme disease remains unclear. This study sought to characterize the psychological status of a group of participants who met criteria for post-Lyme syndrome (PLS). These measures were then used to examine the influence of psychological status on neuropsychological performances. Thirty PLS participants completed a structured psychiatric interview, the Positive and Negative Affect Schedule, the Lyme Symptom Checklist, and a battery of neuropsychological tests. As a group, the PLS participants did not appear to have an elevated incidence of psychiatric disorders, and psychiatric history was not useful for understanding neuropsychological performances or symptom reports. The mood of the PLS participants was characterized by lowered levels of positive affect (PA) and typical levels of negative affect. This combination can be distinguished from depression and is consistent with previous findings of affect patterns in individuals with chronic fatigue syndrome. PA was also linked to both total symptom severity and severity of cognitive complaints, but not to duration of illness, neurological manifestations at initial diagnosis, or treatment history. Relative to published normative data, neuropsychological performances were not in the impaired range on any measure. Neither psychological status nor symptom report were useful for understanding any aspect of cognitive functioning. It is concluded that decreased PA is the most useful marker of psychological functioning in PLS.

Although several studies have suggested that cognitive slowing is a symptom in Lyme disease, it is not clear whether this slowing is general or relates to specific cognitive tasks. This study examined cognitive speed in 25 Lyme disease patients using a mental arithmetic task. These patients showed significant impairments when initiating the cognitive processes involved in counting, but performed as well as healthy participants (n = 23) when the number of counting increments increased. Lyme patients also performed a speeded perceptual-motor matching task as well as healthy participants. Lyme-related initiation speed deficits were significantly correlated with performance on standardized neuropsychological tests, including the Trail Making Test and the Digit Symbol Test, but not with self-reported depression. These results suggest that the cognitive deficits seen on speeded tasks are process specific in the Lyme patient group, and are not the result of generalized slowing.

Cognitive problems are frequently reported in patients with eosinophilia-myalgia syndrome (EMS). This is the first study to explore, in EMS, the relationship between specific neuropsychological deficits and fatigue and pain. Relationships among depression, sleep disturbance, and neuropsychological deficits in EMS were also examined. Neither fatigue nor pain was correlated with memory impairment. Sleep disturbance was significantly correlated with verbal memory impairment, but not with deficits in visuospatial memory. These results suggest that cognitive loss in EMS cannot be attributed to pain or fatigue. Although some aspects of memory impairment may be associated with disturbed sleep, visual memory deficits are clearly independent of sleep deficits and may result from direct effects of the disease on the central nervous system.

Fatigue is commonly reported as an adverse effect of antiepileptic drugs. Ln other disorders, fatigue has been closely correlated with depression. We examined the frequency of fatigue in epilepsy patients, the contribution of depression to fatigue, and the impact of fatigue upon quality of life. We measured fatigue and depression with the Fatigue Severity Scale (FSS) and Center for Epidemiological Studies-Depression scale (CES-D), respectively in 89 patients with epilepsy at an epilepsy center, 26 depressed controls (DC), and 30 normal health adults (NHA). Patients with epilepsy also completed the Quality of Life in Epilepsy (QOLIE-10) scale. Forty-four percent of epilepsy patients met criteria for severe fatigue, while 52% were depressed. The correlation between fatigue and depression was high among epilepsy patients (r = .60, p = .0001). Both fatigue and depression had an inverse relationship with quality of life in epilepsy (p < .0001). Fatigue in epilepsy is common and is closely associated with depression. Fatigue is associated with significant impairment in quality of life in epilepsy. (C) 1998 by Elsevier Science Inc. All rights reserved