Investigating Antihistamine Treatment to Reduce Sensory Over-responsiveness
As complex and powerful as our brains are, we encounter far too much sensory stimulation to reasonably process. Fortunately, our brains have ways to modulate sensory response, tuning into important stimuli and screening out the unimportant. However, sometimes these systems become dysfunctional, failing to screen out unimportant stimuli, leaving us overwhelmed with sensory overload that can have cascading effects impairing cognition and emotion. Other times these brain sensory modulatory systems can fail by honing in on a particular stimulus and over-focusing on it, causing cascading cognitive and emotional impairment, such as occurs in misophonia. Just as we can develop bad habits of action that are maladaptive, we can develop bad habits of sensory processing that are maladaptive. Overcoming these habits can be hard because they become programmed in brain systems that are difficult to consciously control. But just as bad habits of action can be overcome, we are convinced that bad habits of sensory processing can also be overcome. It is just a matter of finding the right approach. We and other researchers are studying brain systems involved in sensory modulation to determine how to best develop therapy for sensory processing disorders.
Histamine, in addition to being a chemical that controls nasal and stomach acid secretions and itch responses also serves as a transmitter between neurons in the brain. We have found that brain histamine systems play important roles in sensory responsivity. In preclinical studies we have shown that a certain type of antihistamine treatment can help reverse sensory gating impairments. In an initial clinical study with people who have difficulty modulating their sensory responsiveness, antihistamine treatment improved sensory screening without producing sedation. This initial study was in people with general sensory over-responsiveness. Further research is necessary to see if this approach could provide useful therapy for people with more specific sensory over-responsiveness such as with misophonia. We hope to determine if this approach with drug treatment can open a space in which the misophonia is relieved so that therapy to overcome the maladaptive sensory processing can have lasting success.