Neutrophil-to-lymphocyte ratio as a potential differential diagnostic marker for alzheimer’s disease, major depressive disorder, and parkinson’s disease

Abstract

Objective: Major depressive disorder, Alzheimer's, and Parkinson's diseases are among the leading causes of dementia in the elderly. These diseases are often misdiagnosed because of overlapping symptoms. This study aimed to evaluate whether neutrophil-to-lymphocyte ratio, which has been used as an indicator of systemic inflammation, can be used for the differential diagnosis of these diseases.

Method: A total of 95 patients with major depressive disorder, Alzheimer's, or Parkinson's disease were enrolled. Neutrophil-to-lymphocyte ratios of the participants were calculated using their past complete blood count results. We compared the three groups according to mean neutrophil-to-lymphocyte ratio and mean neutrophil-to-lymphocyte ratio adjusted for age. We used the receiver operating characteristics curve analysis to predict the sensitivity and specificity of this ratio for the differential diagnosis between depression and Alzheimer's disease.

Results: The mean neutrophil-to-lymphocyte ratios for the depression, Alzheimer's, and Parkinson's disease groups were 2.2 +/- 0.7, 2.9 +/- 1.2, and 2.2 +/- 0.9, respectively (p=0.005). The age-adjusted mean neutrophil-to-lymphocyte ratios for the depression, Alzheimer's, and Parkinson's disease groups were 2.20 +/- 0.93, 2.80 +/- 0.97, and 2.20 +/- 0.96, respectively (p=0.025). Receiver operating characteristics curve analysis predicted that the sensitivity and specificity for the differential diagnosis between depression and Alzheimer's disease were 54.8% and 80.0%, respectively.

Conclusion: This study suggests that a simple arithmetic calculation could help clinicians in the differential diagnosis between depression, Alzheimer's, and Parkinson's disease. Neutrophil-to-lymphocyte ratio can be used as a secondary line of evidence, along with the initial clinical assessment.