Memory functioning in Lyme borreliosis.

BACKGROUND

To objectively measure memory functioning in patients with Lyme borreliosis and examine the relationship between subjective reports of memory dysfunction and actual impairment.

METHOD

A prospective pretreatment study of patients with Lyme borreliosis (N = 21), a patient control group (osteomyelitis, N = 21), and healthy controls (N = 21) was conducted by using tests of verbal memory functioning (California Verbal Learning Test) and self-reported depression (Beck Depression Inventory-Cognitive Index), fatigue (Fatigue Severity Scale), and subjective ratings of memory abilities (Self-Rating Scale of Memory Functions).

RESULTS

Patients with Lyme borreliosis performed worse than healthy controls on verbal memory testing, but did not perform significantly differently from patient controls. Lyme borreliosis patients reported increased fatigue, which was correlated with poorer memory performance. Although the Lyme borreliosis patients rated their memory as more impaired, subjective complaints were not correlated with objective memory scores.

CONCLUSION

These findings suggest impaired memory performance is not specific to Lyme borreliosis and may be a result of evaluating cognitive functioning in patients with physical illness and somatic complaints. Fatigue is a prominent presenting complaint in patients with Lyme borreliosis and needs to be controlled for since it is known to influence neuropsychological performance. Subjective complaints are not correlated with objective memory assessment, so self-report of memory impairment should not be the criterion for inclusion in studies investigating cognitive manifestations of Lyme borreliosis.