Decreased locus coeruleus signal associated with Alzheimer's disease based on neuromelanin-sensitive magnetic resonance imaging technique

ObjectiveNeuromelanin-sensitive magnetic resonance imaging (NM-MRI) technique was used to detect the changes of the locus coeruleus (LC) signals in Alzheimer's disease patients (AD), and to analyze its correlation with cognitive function. Materials and methodsA total of 27 patients with AD, 15 patients with mild cognitive impairment (MCI), and 25 healthy controls (HC) were examined by NM-MRI technique. ImageJ software was used to measure the LC signals. The locus coeruleus signal contrast ratios (LC-CRs) were calculated, along with the measurement of neuropsychological scales. ResultsThe LC-CRs of AD patients were significantly different from that of HC (p = 0.007, 95% CI: -0.053 similar to-0.007). However, such significant differences were not observed between MCI and HC (p = 1.000, 95% CI: -0.030 similar to 0.024), AD and MCI (p = 0.050, 95% CI: -0.054 similar to 0.000). Furthermore, a significant positive correlation was identified between LC-CRs and MMSE sub item Drawing (r = 0.484, p = 0.011) in the AD group, MoCA sub item Attention (r = 0.519, p = 0.047) in the MCI group. The area under the curve of LC-CRs in the diagnosis of AD was 0.749 (p = 0.002, 95% CI: 0.618 similar to 0.880), with a sensitivity of 85.2% and a specificity of 56.0%. ConclusionThe NM-MRI technique could quantify the pathological degenerations of the LC in AD. Such LC degenerations can be employed to distinguish AD from healthy elderly.