A BOLD move

Abstract

Since its first discovery in the early 1990s, the blood oxygenation level–dependent (BOLD) effect as measured by fMRI has been increasingly used in the neuroscientific study of brain activity. Similar to PET, it is based on the coupling of neuronal firing with increases in blood flow, but instead it relies upon magnetic field changes consequent to endogenous blood oxygenation rather than injected radioactivity. It is thus noninvasive and repeatable, relatively low in cost, with high spatial and temporal resolution. Consequently, there have been growing efforts to implement fMRI in clinical practice, successfully in some areas, such as neurosurgical preoperative planning.1 In this issue of Neurology ®, O'Brien et al.2 present evidence suggesting that fMRI may be useful in the early detection of functional brain changes that ultimately lead to Alzheimer disease (AD). The authors measured hippocampal BOLD signals during an associative memory paradigm, combined with clinical assessment of 51 older subjects without dementia with follow-up after 2 years. Study participants were divided based on their Clinical Dementia Rating (CDR) scores of 0 or 0.5 (the …