Cognitive Deficits Reflecting Diffuse and Focal Brain Lesions Caused by Slow Growing Brain Tumors - Low-grade Gliomas

Abstract: The overall purpose was to characterize the impact that low-grade glioma (LGG) – a type of slowly growing brain tumor – has on cognitive functions.Paper I was an in-depth analysis of cognitive dysfunction of patients with histological proven LGG. The pattern varied among patients, revealing three subgroups: 1) patients with severe cognitive dysfunction; 2) patients with mild cognitive dysfunction; 3) patients with selective dysfunction due to tumor localization. In the first two subgroups the patients had slowed information-processing speed. Patients with a favorable prognosis performed better than those with unfavorable prognosis. Nonworking patients showed more pronounced dysfunction than working patients.Paper II studied cognitive functions of patients who were in the early stage of the disease and had not yet received any major medical treatments. Patients’ performances ranked at the lower end of normal limits, which contrasted with those of the individually matched controls, whose performances ranked at the upper end. Patients had slower information-processing-speed and less effective executive functions. Patients with frontal tumors had various executive problems due to tumor localization. Paper III investigated cognitive impairment at the individual level in relation to neurological symptoms, radiological characteristics of the tumor, depression, and fatigue. Paper III included the same patients as Paper II. The results showed that the majority of the patients did not have more than selective impairment. One subgroup, consisting of younger patients with large left frontal tumors showed obvious cognitive impairment, including slowed information-processing speed.The thesis showed that diffuse brain injury was closely connected to LGG. A subgroup of patients in the early phase of the disease showed signs of mild diffuse brain injury. The majority of the patients who were in later stage of the disease displayed cognitive signs of diffuse brain injury.