Brain Imaging in Patients With Diabetes

Abstract

Diabetes is associated with impaired cognitive functioning and an increased risk of dementia (1,2). Patients with type 1 diabetes may show mild to moderate slowing of mental speed and diminished mental flexibility, whereas learning and memory are relatively spared (3). In patients with type 2 diabetes, cognitive impairment may be relatively more pronounced, particularly affecting verbal memory or complex information processing (4,5). The pathogenesis is still uncertain, but chronic hyperglycemia, vascular disease, repeated hypoglycemic episodes, and possibly direct effects of insulin on the brain have been implicated (6). Brain imaging studies can help to clarify the pathogenesis. An increasing number of studies report both focal vascular and more global (e.g., atrophy) cerebral changes, but the results are not always consistent. Our aim was to systematically review brain imaging studies in patients with diabetes. Data on the relation of imaging with cognition and with relevant disease variables were also recorded. Medline and EMBASE (1966 to February 2006) were searched with the following medical subject heading terms: computed tomography (CT) and magnetic resonance imaging (MRI) studies: white matter, leukoaraiosis, lacunar infarction, subcortical, periventricular, brain, cerebral, hippocampus, atrophy, MRI, magnetic resonance imaging, CT, and tomography; magnetic resonance spectroscopy (MRS) studies: magnetic resonance spectroscopy, MRS, brain, and cerebral; positron emission tomography (PET), single-photon emission CT (SPECT), and Xenon-enhanced CT studies: cerebral blood flow, glucose metabolism, brain, cerebral, PET, SPECT, Xenon, positron emission tomography, single-photon emission tomography, and tomography; all combined with “diabetes.” The abstracts were screened and potentially relevant articles retrieved. These articles were included if they met the following four criteria: 1 ) original article, written in English, on brain imaging in adult patients with diabetes in comparison with control subjects; 2 ) diagnostic criteria for diabetes specified; 3 ) sample size of at least 20 diabetic patients, or a total sample …