Title:Robust Discovery of Mild Cognitive Impairment Subtypes and Their Risk of Alzheimer's Disease Conversion Using Unsupervised Machine Learning and Gaussian Mixture Modeling
Volume: 18
Issue: 7
Author(s): Fahimeh Nezhadmoghadam*, Antonio Martinez-Torteya, Victor Treviño, Emmanuel Martínez, Alejandro Santos, Jose Tamez-Peña and Alzheimer’s Disease Neuroimaging Initiative
Affiliation:
- Tecnologico de Monterrey, School of Engineering and Sciences, Ave. Eugenio Garza Sada 2501, Monterrey, N.L., 64849,Mexico
Keywords:
Alzheimer's disease, mild cognitive impairment, latent class analysis, consensus clustering, Gaussian mixture model, intracranial volume.
Abstract:
Background: Alzheimer’s Disease (AD) is an irreversible, progressive brain disorder that
slowly destroys memory and thinking skills. The ability to correctly predict the diagnosis of Alzheimer’s
disease in its earliest stages can help physicians make more informed clinical decisions on
therapy plans.
Objective: This study aimed to determine whether the unsupervised discovering of latent classes of
subjects with Mild Cognitive Impairment (MCI) may be useful in finding different prodromal AD
stages and/or subjects with a low MCI to AD conversion risk.
Methods: Total 18 features relevant to the MCI to AD conversion process led to the identification of
681 subjects with early MCI. Subjects were divided into training (70%) and validation (30%) sets.
Subjects from the training set were analyzed using consensus clustering, and Gaussian Mixture Models
(GMM) were used to describe the latent classes. The discovered GMM predicted the latent class of the
validation set. Finally, descriptive statistics, rates of conversion, and Odds Ratios (OR) were computed
for each discovered class.
Results: Through consensus clustering, we discovered three different clusters among MCI subjects.
The three clusters were associated with low-risk (OR = 0.12, 95%CI = 0.04 to 0.3|), medium-risk (OR
= 1.33, 95%CI = 0.75 to 2.37), and high-risk (OR = 3.02, 95%CI = 1.64 to 5.57) of converting from
MCI to AD, with the high-risk and low-risk groups highly contrasting. Hence, prodromal AD subjects
were present in only two clusters.
Conclusion: We successfully discovered three different latent classes among MCI subjects with varied
risks of MCI-to-AD conversion through consensus clustering. Two of the discovered classes may represent
two different prodromal presentations of Alzheimer´s disease.
