Classification of patients with dementia in a late life depression cohort using structural MRI

Abstract

AbstractBackgroundLate life depression (LLD) is a risk factor for cognitive impairment, with up to 40% of depressed older adults showing persistent cognitive deficits even after symptom remission. Over 20% of Alzheimer’s disease patients exhibit depression‐like symptoms which can represent an early marker of disease (Tsuno et Homma., 2009). We hypothesized that automated classification algorithms trained on structural MRI could predict adjudicated diagnosis of cognitive impairment (CI) in this cohort.MethodOur study evaluated 295 patients with LLD. An adjudication committee consisting of two board‐certified psychiatrists and a clinical neuropsychologist determined ground‐truth labels for patient diagnostic results of CI (N = 145) or No CI (N = 150). Patients underwent T1‐weighted scans, which were segmented with Freesurfer 6.0.1 (freesurfer.net) packaged with fMRIPrep 1.5.8 (fmriprep.org) using the Desikan‐Killiany atlas. Cortical thickness and volumetric data were obtained along with demographic parameters. Freesurfer data was then regressed against estimated total intracranial volume. 11 classifications algorithms implemented in R were trained and tested on 209 and 88 patients, respectively, to classify if a patient has CI. All continuous‐valued data were normalized with respect to the training set mean and standard deviation.ResultTable 1 shows results from multiple classifications algorithms, including high sensitivity, specificity, and accuracy from adaptive boosting algorithms. The latter algorithms iteratively optimize a set of binary classification tree algorithms (Freund et Schapire., 1996).ConclusionVolumetric structural MRI biomarkers trained with machine learning classifiers can adequately categorize depressed older adults with CI which could assist the adjudication process. Future work incorporating structural MRI biomarkers with gold standard clinical data may improve earlier detection of cognitive impairment stemming from a neurodegenerative etiology.