Cognitive effects of pegylated interferon in individuals with primary brain tumors.

Cognitive changes associated with interferon treatment include impaired verbal memory, attention, processing speed, and executive functioning. Pegylated interferon is a relatively new, long-lasting form of interferon alpha, but data regarding its cognitive effects in brain tumor patients are limited. Participants in this study were 35 primary brain tumor patients who received pegylated interferon at tumor recurrence. A neuropsychological battery assessed verbal memory, executive functioning, attention, information processing speed, and language functioning. Individual growth curve analyses were used to estimate cognitive change throughout treatment with interferon. Results revealed performance declined on a task of psychomotor speed and upper extremity dexterity. Although decline in a few tests was found, its degree may have been reduced because individuals were tested after tumor recurrence where a substantial amount of cognitive change had already potentially occurred due to surgery, radiation therapy, and chemotherapy. Thus, participants may not have been starting at their baseline cognitive status and the potential neurotoxic effects of interferon may have been obscured by prior treatments. An alternative explanation, however, is that treatment with pegylated interferon did not produce further impairment and patients experienced stability in their cognitive functioning.