The negative predictive value of Amyloid Imaging in differentiating patient’s with depression and prodromal Alzheimer’s diseas

Objectives Patients with depressive syndromes in late life present with cognitive impairment is difficult to differentiate from dementia patients who present with depression symptoms in the clinical setting. The aim is to evaluate Amyvid PET in differentiating patient’s with depression and prodromal AD.

Methods Evaluate 32 consecutive patients in our clinic who underwent clinical Amyvid PET scans. These patients were later confirmed to be 11 diagnosed major depressive patients and 21 with clinical diagnosed AD or MCI. Amyloid images were interpreted by nuclear medicine physicians according to the Amyvid guideline. Whole brain voxel-based group comparisons were performed.

Results Patients with confirmed diagnosis of major depression had significant less amyloid accumulation compared with those dementia patients. The percentage of positive amyloid scan is significantly lower among the depression group (2/13, NPV 85%) compared with those dementia group (19/19). Those two positive Amyvid patients from the depression group eventually received diagnosis of dementia in their follow-up clinical evaluations. The depression group has significantly less amyloid deposition in the posterior cingulate, bilateral parietal and frontal cortices (p < 0.001) than dementia subjects. Whole brain voxel-wise analysis revealed a significantly lower SUVR in depressed patients in the frontal, parietal, temporal and occipital areas (p < 0.05, FDRcorrected). There is no significant correlation between global amyloid burden and prior depression episodes, age at onset of depression, time since onset of first depression, or treatment of depression including ECT therapy.

Conclusions Significant less amyloid burden is found in patients with major depression relative to dementia subjects in specific brain regions, despite no differences in age, sex, education between the two groups. Great negative predictive value of Amyvid PET scan is seen in differentiating patients with depressive syndrome and those dementia patients with presentation of depression symptoms.