###### Abstract  
Early detection of motor intentional disorders associated with dysfunction in the action-intention system of the brain is clinically important to provide timely intervention. This study developed a force tracking system that can record forces exerted by the index finger while tracking 5 N, 10 N, 15 N, and 20 N of target forces varying over time. The force tracking system quantified force control measures (initiation time IT; development time, DT, maintenance error, ME; termination time, TT; tracking error, TE) for the individual and overall force control phases. This study evaluated the effectiveness of the force tracking system for a normal control group (\(n=12\)) and two patient groups diagnosed with subcortical vascular mild cognitive impairment (svMCI, \(n=11\)) and subcortical vascular dementia (SVaD, \(n=13\)). Patients with SVaD showed significantly worse force control capabilities in IT (0.84 s) and ME (1.71 N) than those with svMCI (0.64 s in IT, and 1.38 N in ME). Patients with svMCI had significantly worse capabilities in IT, ME, and TE (3.80 N) than the control group (0.49 s in IT, 0.78 N in ME, and 3.07 N in TE). The prevalence rates of force control capabilities lower than the 99% confidence interval of the control group ranged from 17% to 62% for the two patient groups. The force tracking system can sensitively quantify the severity of the force control deficiencies caused by dysfunction in the action-intention system of the brain. type: motor intentional disorders; subcortical vascular mild cognitive impairment; subcortical vascular dementia +
Footnote †: journal: Applied Sciences  
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initiation is tested by asking a patient to lift the arm ipsilateral to the lesion as the hand is touched [3; 5]. Motor impersistence with dysfunction in maintenance is assessed by asking a patient to keep the arms extended for 20 s [4; 6; 7]. Motor perseveration with dysfunction in termination is tested by asking a patient to draw the Luria loop [8]. Although these observational tests are commonly used, they can neither quantify the severity of dysfunction in the action-intension system nor detect mild dysfunction [9; 10]. Quantitative assessment of dysfunction in the action-intention system is clinically important in several ways. Quantification of the severity of dysfunction allows early detection of MIDs, facilitating timely clinical interventions from an early stage [11]. For example, the quantification of severity can help in early screening of a patient with subcortical vascular mild cognitive impairment who may have a dysfunction in the action-intention system [12]. In addition, the quantification of severity helps clinicians monitor the symptom progression of a patient who is at an increased risk of developing severe symptoms and dementia. Lastly, the quantified severity can be used to evaluate the effectiveness of treatments provided to patients with MIDs. A few recent studies have demonstrated that force control tests can objectively quantify dysfunction in the action-intention system. [PERSON] et al. [13] proposed the four force control tests for each force phase (force initiation, development, maintenance, and termination phases). Later, [PERSON] et al. [14] used the force control tests and found that force control capabilities of brain-damaged patients were far inferior to those of normal controls. [PERSON] et al. [11] and [PERSON] et al. [15] applied the force control tests and revealed that the force control capabilities of brain-damaged patients significantly differed as compared with normal controls. These results indicate that measuring force control capabilities using the force control tests can objectively quantify the severity of dysfunction in the action-intention system. The present study developed a quantitative assessment method of force control capabilities using a force tracking test.