The phone as a psychiatric tool: what is “digital phenotyping”

One of the newest lines of psychiatric research has left the laboratory and moved into our pockets. Digital phenotyping is the use of passively collected data from smartphones and wearable devices to track, in real time, signals that reflect mental state.

What is measured

Researchers in this field analyse patterns such as:

• Sleep: duration, regularity and fragmentation, inferred from the phone’s movements and activity;
• Speech: the rhythm, pauses and prosody of phone conversations (with the user’s consent);
• Movement and physical activity: steps, distances travelled, time spent sitting;
• Social interaction: how often messages and calls are exchanged, the size of the network of active contacts;
• Phone use patterns: times of day, session length, changes in habits.

On its own, each piece of data says little; together, they make up an individual “digital phenotype”.

What is being researched

The main aim is to predict changes in mental state before the patient notices them. Pilot studies have shown that:

• changes in sleep patterns can precede a depressive relapse by days;
• a drop in social activity can signal the start of a depressive episode;
• changes in speech can predict the onset of psychotic episodes;
• a sudden increase in night-time activity can signal the onset of a hypomanic state.

The idea is that if these signals can be detected automatically, intervention can come earlier, before the patient reaches an acute crisis.

Promises and problems

Promises:

• continuous monitoring, not just at consultations;
• early detection of relapses;
• objective data that complement the patient’s subjective account;
• accessibility: the phone is already part of the patient’s life.

Problems:

• Confidentiality. This data is extremely sensitive. Who owns it? Who has access? How is it protected?
• Genuine informed consent. What are patients really consenting to, if most of them do not understand what data can be extracted?
• Overburdening the patient. An app that continuously tracks and reports “changes in mental state” can produce anxiety of its own.
• Risk of discrimination. Who will have access to this data in the future: insurers, employers, courts?

Where we are today

Digital phenotyping is still, to a large extent, a field of research. A few commercial apps exist, but their clinical use is limited. In the current context, the data can complement clinical assessment, but cannot replace it.

For patients, it is worth knowing that the data on their phone, even when it seems trivial, can have medical value. If you use health or sleep-tracking apps, check what data they collect and who they share it with. For clinicians, it is a development worth following, with measured enthusiasm and constant attention to the ethical implications.

See also: Psychiatry