Table 2.

Targeted disorders and ML^a techniques.

Disorder	NRb	ML technique (NR of usage)	References
Parkinson disease	87	SVMc (34), ANNd (23), RFe (9), KNNf (6), GBg (5), GMMh (2), NBi (1), DTj (3), SVRk (2), LRl (1), PAm (1)	[17,40,42,44,48-102,117-135,168,170,171, 180,181,183-185,188]
Dementia, Alzheimer disease	18	SVM (8), KNN (2), LR (2), RF (3), ANN (3)	[103-110,136-139,172-176,179]
Cognitive impairment/mild cognitive impairment	8	SVM (2), LR (2), RF (2), ANN (2)	[112-116,150,177,178]
COVID-19	7	ANN (3), SVM (1), RF (1), KNN (1), GB (1)	[143-147,156,157]
Amyotrophic lateral sclerosis	4	SVM (1), RF (2), MeMLn (1)	[46,158-160]
Depression	4	ANN (3), SVM (1)	[140-142,161]
Cardiovascular disorders	2	KNN (2)	[111,186]
Essential tremor	2	SVM (2)	[162,163]
Multiple sclerosis	2	ANN (1), RF (1)	[149,164]
Stroke	2	ANN (2)	[148,153]
Asthma	1	RF	[182]
Autism	1	ANN	[151]
Fatigue	1	SVM	[187]
Chronic obstructive pulmonary disease	1	RF	[154]
Neurodegenerative cognitive complaint	1	SVM	[165]
Functional dysphagia, oropharyngeal dysphagia	1	RF	[166]
Influenza disease	1	KNN	[167]
Neurological disease	1	KNN	[169]
Traumatic brain injury	1	ANN	[152]

^aML: machine learning.

^bNR: number of studies.

^cSVM: support vector machine.

^dANN: artificial neural network.

^eRF: random forest.

^fKNN: K-nearest neighbor.

^gGB: gradient boosting.

^hGMM: Gaussian mixture model.

ⁱNB: naïve Bayes.

^jDT: decision tree.

^kSVR: support vector regression.

^lLR: logistic regression.

^mPA: passive aggressive.

ⁿMeML: mixed effect machine learning.