There is a fundamental gap in our understanding of how chronic hyperventilation (HV), which is present in
approximately half of anxious patients and is a significant barrier to treatment response, affects brain function
and anxiety-related symptoms. This gap represents an important problem because, until it is filled, the field will
not be able to precisely identify mechanistic targets for new treatment development. The long-term goal is to
improve treatment efficacy for anxiety disorders by targeting specific biomarkers of illness and recovery, and
by matching patients to specific interventions based on these biomarkers. The objective here is to examine
differences in brain function between hypocapnic (hyperventilating) and normocapnic anxious patients, as well
as healthy control subjects; and to determine the extent to which parameters of voluntary HV are similar to or
different from the chronic and non-volitional HV seen in patients with anxiety disorders. The central hypothesis
is that chronic, anxiety-related HV is associated with persistent changes in electrocortical activity, and that HV
and its associated CNS sequelae lead to greater anxiety sensitivity and further HV in a vicious cycle. The
rationale for the proposed research is that (a) current treatments, though effective, do not benefit half of the
patients who receive them; (b) HV may be a critical reason for this nonresponse; and (c) by examining the
relationship between anxiety, chronic HV, and CNS changes, and by determining the causal relationship
between HV and indices of anxiety, we will be able to identify meaningful biological targets that would allow us,
for the first time, to pursue clinical trials of anxious patients with assignment to different treatments based on
the presence or absence of a particular transdiagnostic biomarker. The proposed pilot study will test this
hypothesis by pursuing three specific aims: (1) to determine the relationship between baseline hypocapnia and
physiologic, CNS, and self-report indices of HV and anxious responding in adults with anxiety disorders; (2) to
examine the causal relationship between voluntary HV and physiologic, CNS, and self-report indices of HV and
anxious responding in adults with and without anxiety disorders; and (3) to explore similarities and differences
between the relationship between voluntary and chronic HV. Participants will be examined under conditions of
normal breathing and voluntary HV. EEG and electrodermal activity will be used to measure CNS and
physiologic indices of both HV and anxiety, allowing the examination of interactions between respiratory- and
anxiety-related factors and thereby clarify effects that have thus far been confounded in research. The
approach is innovative, because it uses multi-level analysis and will compare, for the first time, voluntary and
naturally-occurring HV. The proposed research is significant, because it is expected to advance the field's
understanding of the role of HV in chronic anxiety, will help clarify why hypocapnic patients respond less well to
treatment, and will generate targets for novel treatment development.