Only 41% of US adults suffering from a mental health condition access mental health services in a given year. There is an urgency to objectively diagnose, monitor over time, and provide evidenceābased interventions for individuals with mental illnesses, particularly those who are unable to access traditional psychological or psychiatric services due to geographical, financial, or practical barriers. These reports are often subjective and include patients' retrospective recall biases (eg, to downplay or overestimate symptoms), cognitive limitations (eg, memory of episodes and environment, causal inference), and social stigma. 3 Current approaches to the assessment and monitoring of psychiatric conditions rely primarily on intermittent reports from affected individuals or their caregivers. 1, 2 These disorders have a larger economic impact than cancer, cardiovascular diseases, diabetes, and respiratory diseases, but societies and governments spend much less on mental disorders than these other disorders. Mental health disorders in the United States affect 25% of adults, 18% of adolescents, and 13% of children.