An experimental at-home device is a promising noninvasive treatment approach for anxiety disorders, results from an open-label pilot trial suggest.
The small study showed that users of mechanical affective touch therapy (MATT) improved their anxiety and depression symptoms, which corresponded to positive changes in alpha and theta oscillatory activity.
“MATT is part of a larger movement toward developing therapeutic devices that patients can self-administer at home,” said study author Linda L. Carpenter, MD, professor of psychiatry at the Brown University and Director of the Neuromodulation & Neuroimaging Core at Butler Hospital. Providence, Rhode Island, said Medscape Medical News, adding that the new study is a step in the right direction to improve the technology used to treat anxiety disorders.
The study was published online April 22 at Frontiers in Psychiatry.
Robust security profile
Noninvasive therapeutic peripheral nerve stimulation is being investigated for anxiety as well as pain and depression. Nerve activation is achieved by delivering electrical or mechanical energy, although most devices to date have used electrical stimulation.
Although electrical stimulation is considered low risk, mechanical stimulation that activates somatosensory pathways has an even more robust safety profile, the researchers note.
The MATT device targets specialized C-tactile (CT) fibers in peripheral unmyelinated group C nerve fibers that fire when stroked at speeds perceived as pleasurable or comforting.
To use the device, participants wear headphones with a small vibrating piece that rests on the mastoid bone behind each ear. These parts deliver gentle vibrations that can be adjusted by patients.
During the development of MATT stimulation, researchers noted that a 10 Hz isochronic wave, cycling 2 seconds on and 2 seconds off, induced a state of relaxation and increased occipital alpha oscillations in pilot study participants.
The current study was designed to confirm preliminary signals of efficacy and feasibility. The sample included 22 patients (mean age 37.3 years, 72.7% female, 77.3% Caucasian). All study participants were diagnosed with an anxiety disorder and had at least moderately severe symptoms of anxiety. Some also had symptoms of panic or depression.
Many participants were taking medications that weren’t effective, and they wanted to find a non-drug method to relieve their symptoms, Carpenter said.
What is the mechanism?
Participants learned to administer the stimulation and adjust the vibration intensity to a level where it was consistently detectable but not uncomfortable. Then they were given a MATT device to use at home at least twice a day for 20 minutes.
Patients kept daily diaries documenting device use, adverse effects, and technology issues. In-person assessments took place at 2 and 4 weeks.
The researchers collected the resting EEG immediately before and after the second stimulation session and again after 4 weeks of MATT use.
At baseline and after 2 and 4 weeks, patients self-reported their anxiety using the 7-item questionnaire. Generalized anxiety disorder (GAD-7), depression with the Beck Depression Inventory (BDI) and stress with the Perceived Stress Scale (PSS). They also reported symptoms with the Depression, Anxiety, and Stress Scale (DASS).
Researchers have also studied “interoceptive awareness” or being aware of your body and your internal feelings. To do this, they asked participants to complete the 32-point Multidimensional Assessment of Interoceptive Awareness before and after treatment.
Interoceptive awareness “is a whole new area of interest in neuroscience and brain health,” Carpenter said. “The hypothesis was that one of the ways this device might work is that the vibrations would travel to the insular cortex, the part of the brain that involves mindfulness and self-awareness.”
Reduction of symptoms
In the full sample of 17 participants, mean anxiety and depression symptom scores fell significantly between baseline and 4 weeks (all P
The study also showed that mindfulness was improved. The MAIA total score increased from 83.1 to 93.5 (P = 0.014).
Device users had increased alpha and theta brainwave activity, results that “go hand in hand with the concept of decreased anxiety,” Carpenter said. She noted a recent study from the same patient population showed that the device improved functional brain connectivity.
This current study was too small to pick up signals showing the device was effective in a particular subpopulation, Carpenter said.
Unlike other stimulation interventions that require clinic visits, patients use the MATT in the comfort of their own home and at their convenience.
However, there are still questions surrounding the use of the non-invasive device. For example, Carpenter said, it’s unclear if it would be more effective if combined with psychotherapy or if patients can use it while sleeping and driving. A next step could be a sham controlled trial, she said.
The study was supported by Affect Neuro Inc, developer of MATT therapy, and the National Institute of General Medical Sciences. Carpenter reports receiving consultancy fees from Affect Neuro.
Frontal psychiatry. Published online April 22, 2022. Full Text