The Role Of Wearable Technology In Mental Health Monitoring And Support

Introduction

With the rise in mental health awareness, you would think that getting aid and assessment for mental illness would be easier than ever. Unfortunately, healthcare systems are often under-resourced, and the long wait times and insufficient support can be potentially dangerous to patients in need.

This increase in mental health awareness has been correlated with an increase of smartphones and smartwatches that collect and interpret information about our bodies. A wearable device for mental health monitoring feels close enough to touch. Additionally, mental illness is often diagnosed and treated subjectively from the patient self-reporting to a healthcare professional. This is unreliable and results can be skewed by personal bias and human error. Technology may be the only way to definitively detect and diagnose mental illness

But can the body really communicate what’s happening in our heads to a device? And are we in an age where we can objectively distinguish anxiety and depression from physiological clues?

Anxiety

Anxiety is a necessary emotion as the ‘fight or flight’ reaction is a part of our natural survival instincts. Anxiety occurring when there is no threat is considered a disorder. Out of all mental and physical conditions, anxiety was ranked as the sixth leading cause of healthy years lost to disability globally by WHO in 2015.¹

The cognitive symptoms of anxiety would be difficult to measure objectively, such as:

• Hypervigilance
• Negative thoughts or memories
• Fear of losing control
• Fear of physical injury

Physical symptoms of anxiety include:²

• Increased heart rate
• Chest pain
• Rapid breathing
• Shortness of breath
• Dizziness
• Tingling
• Numbness
• Hot flashes
• Upset tummy

All these symptoms are related to the sympathetic nervous system.

What happens to your body during anxiety?

A system of nerves in the body lets us detect and respond to the world around us. The autonomic nervous system connects the brain to most of the internal organs and controls automatic functions like goosebumps, sweating, heart rate, the immune system fighting diseases, and the pancreas releasing hormones.

The sympathetic nervous system, a part of the autonomic nervous system, plays a large role in your ‘fight or flight’ response and other processes that assist you during times of need. It opposes the parasympathetic nervous system, which controls basic functions when your body is not experiencing a ‘fight or flight’ response, like resting heart rate and digestion.

In stressful situations, the sympathetic nervous system is stimulated and the parasympathetic nervous system is dampened. The sympathetic nervous system will cause an increase in heart rate, respiratory rate, and electrical properties of the skin.

Wearable technology for anxiety

Cardiac activity

Heart rate increases during times of anxiety. This is due to an increase in blood being distributed to vital organs. Other factors that can be measured include the amount of blood pumped by each heartbeat (stroke volume), and the contraction and dilation of vessels changing local blood pressure (vascular activity).

Heart rate variability has a high correlation with the autonomic nervous system. If someone has low heart rate variability, this indicates that the homeostasis of their autonomic nervous system is impaired and they may have a reduced ability to deal with stressors. This is linked to mental illnesses like anxiety, panic disorders, and depression.

One way to measure heart rate is an ECG (echocardiography). This system involves electrodes measuring the electrical potential generated by cardiac muscles. Issues arise with using this technology long-term, as the electrode-skin interface has to be tight to eliminate electrical noise. However, to be a viable wearable technology for the general public, it should be comfortable. Additionally, sweat at the electrode-skin interface can cause relative motion and increase resistance to AC signals. Flexible and wireless ECG electrodes have been researched and developed.³ Other developments include an ECG e-tattoo, ECG in textiles, and even electrodes that can be painted on. None of these are commercially available, although they may be in the future.

Respiration

Respiration rate is a good indicator of emotional distress. During a panic attack or an episode of anxiety, shortness of breath or hyperventilation is common. This is due to the body believing it needs more oxygen to fight a ‘threat’.³ Respiratory patterns include respiration rate, the ratio of air inhaled to exhaled, breathing irregularities, and the change in chest size. Detecting breathing by difference in chest size is the method that allows for the most mobility, while it is being measured, unlike spirometry, a machine that detects breathing capability from the patient putting their lips on a mouthpiece.

Chest movement can be detected using strain sensors, a band of a piezoresistive material wrapped around the chest , meaning that if it is stretched the resistivity of the material is changed.³

Perspiration

Sweat is often stimulated by the sympathetic nervous system under stress. Sweat contains ions, small molecules, and macromolecular substances, and is electrically conductive. Secretion of sweat can be measured by the conductivity of the skin, called the electrodermal activity (EDA). This signal is retrieved from two electrodes on the skin. While sweat comes from all areas of the body, there is a high concentration of sweat glands on the fingers and palms. Therefore, these electrodes can be placed on a ring.³

Stress

Anxiety and stress are similar conditions and are often confused. Stress is not a mental illness, but it is a state of emotional strain that may cause or worsen mental illness. Stress is caused by something external while anxiety disorder is persistent and related to internal thoughts, often an out-of-proportion response to a situation.⁴

What happens to the body during stress?

Stress is a threat to the internal environment of our bodies. This internal environment’s stability, and the environment’s ability to maintain this stability, is called its homeostasis. When a stressor causes stress and threatens this homeostasis, the response is called a stress response.⁴

A stress response involves the body releasing hormones like adrenaline into the bloodstream, and your heart rate and blood pressure increasing. One of the hormones released during stress is cortisol. Cortisol keeps you on high alert by triggering your liver to release glucose, providing a fast energy source to the body.

If the stress is chronic, the stress hormones can build up in the bloodstream and cause further health problems. Some problems this can lead to are stomach ache, diarrhoea, appetite increase, weakened immune system, loss of sleep, increased blood pressure, and increased blood sugar.⁵ Chronic stress is dangerous and can increase the risk of cardiovascular disease, the leading cause of death worldwide.⁶

Wearable technology for stress

Stress can be detected molecularly. Cortisol can appear in multiple bodily fluids. There are various ways to detect molecules, but this article will focus on the ones that can be miniaturised. One way to detect the cortisol in sweat is aptasensors. These have strands that fit the target substance via molecular interactions. Another way is using a molecularly imprinted polymer (MIP). These are polymerised (turned into the material called polymer) in the presence of the target substance, removing it and leaving imprinted cavities. Immunosensors use antibodies to initiate a molecular binding event, creating a physical signal. These can be implemented into wearable technology like textiles, patches, and even bandages.³

Depression

Depression is estimated to affect 5% of adults worldwide.⁷ It is defined as a feeling of worthlessness and emptiness, a loss of motivation, and an inability to feel pleasure. It can cause issues with concentration, sleep, and suicidal ideation.

If you or anyone you know is experiencing depression, it is important to get help and know you’re not alone. You can call Samaritans at 116 123 any time, anywhere, about anything.

What happens to the body during depression?

Depression may be the most challenging to detect physically out of the mental illnesses touched on in this article. Depression causes a lack of motivation in an individual which usually results in minimal physical activity, and therefore a lower heart rate. It is more likely to occur in physically ill and disabled individuals.

There are studies on changes in the brain, such as a reduction in the dorsolateral prefrontal cortex grey matter in late-life depression, the part of the brain involved in decision-making and working memory.⁸

Wearable technology for depression

Brain activity

Our brain functions through electrical activity between cells. The brain interacts with other body parts through sending and receiving electrical signals, as well as communicating with other parts of the brain. It is how our bodies perform processes to help us function, like thinking, breathing, feeling pain, and moving.

Electrical activity in the brain is detected by EEG (electroencephalography). It involves electrodes placed on the scalp that can be placed individually, as a band or cap. The electrical activity is tracked through waves. The waves change when the individual wearing the EEG moves, talks, sleeps, reacts to stimuli, or has a seizure. Unfortunately, while there is promising research into features of the EEG waves that indicate depression, algorithms to detect depression via EEG are not yet dependable. There are similar devices used for epilepsy and seizure detection, and research into increasing the comfortability, portability, and accuracy of these devices could result in a similar wearable device for detecting depression.⁹

Another way of detecting brain activity is function near-infrared spectroscopy (fNIRS), in which near-infrared light is shone on someone’s head with a detector right next to it to sense any reflected light. Haemoglobin, a protein found in the blood that carries oxygen, absorbs infrared light, enough so that areas of high haemoglobin concentration can be detected. A study performed using this method found haemoglobin concentration in certain areas of the brain had a strong correlation with those diagnosed with major depressive disorder.¹⁰

Movement

Wearable devices for tracking movement are some of the most common. It is integrated into our smartphones and wrist-worn fitness trackers. Depression affects the motivation of an individual, and episodes can reduce their physical activity. A study has shown that data collected about an individual’s movements can accurately predict the presence of depression over 80% of the time.¹¹

Summary

Over the past decade, wearable technology has become commonplace, particularly smartphones and wrist-worn devices. Sensors used in hospital settings are increasingly portable and accessible to the general public. This portability is made possible by wireless data transmission from a bodily sensor to a host device, often a mobile phone, flexible electronics, and efficient energy storage. Accessible and portable technology for monitoring mental health can reduce the burden on the healthcare system, and even provide more accurate and objective parameters in diagnosing mental illness. Current stress-level management relies on subjective self-reporting to mental health professionals, which is time-consuming with limited accessibility and subject to unreliable results.

Mental health does result in physical changes to the body. Anxiety can cause sweating, increased heart and respiratory rate, and a lower heart rate variability. Stress affects the heart and respiratory rate, and hormones being released into the bloodstream to trigger a burst of energy. Depression affects brain activity, grey matter, and physical activity.

There is plenty of research into wearable technology for monitoring and supporting mental health, but little is readily available to those who need it. Multiple physical indicators have the potential to be utilised in recognising and diagnosing mental health conditions.