Angela Attwood

7.5% carbon dioxide inhalation increases threat processing in humans

Inhalation of 7.5% CO2 increases anxiety and autonomic arousal in humans, and elicits fear behavior in animals. However, it is not known whether CO2 challenge in humans induces dysfunction in neurocognitive processes that characterize generalized anxiety, notably selective attention to environmental threat. Healthy volunteers completed an emotional antisaccade task in which they looked toward or away from (inhibited) negative and neutral stimuli during inhalation of 7.5% CO2 and air. CO2 inhalation increased anxiety, autonomic arousal, and erroneous eye movements toward threat on antisaccade trials. Autonomic response to CO2 correlated with hypervigilance to threat (speed to initiate prosaccades) and reduced threat inhibition (increased orienting toward and slower orienting away from threat on antisaccade trials) independent of change in mood. Findings extend evidence that CO2 triggers fear behavior in animals via direct innervation of a distributed fear network that mobilizes the detection of and allocation of processing resources toward environmental threat in humans.

Effects of acute anxiety induction on speech perception: are anxious listeners distracted listeners?

Improving the validity of speech-recognition models requires an understanding of the conditions in which speech is experienced on a daily basis. Listening conditions leading to a degradation of the signal (e.g., noise) can be modeled at the interface between sensory processes and long-term memory for words. Conditions leading solely to an increase in cognitive effort can be modeled in a similar fashion. Specifically, Mattys and Wiget (2011) showed that dividing attention between a speech task and a nonlinguistic visual task causes a lexical drift, whereby listeners tend to ignore important acoustic details in the speech signal and rely too much on the lexical plausibility of its content. In contrast, little is known about the effect on speech perception of listening conditions that neither degrade the signal nor overtly require additional mental operations— for example, listening to speech in a state of anxiety, a condition often encountered in everyday life. Research shows that anxiety is associated with a broad dysregulation of attentional control and enhanced sensitivity to distraction (Bishop, 2009; Eysenck, Derakshan, Santos, & Calvo, 2007). We therefore hypothesized that the effect of anxiety on speech perception might be similar to that of divided attention. To test this hypothesis, we measured the effect of acutely induced anxiety on performance of a classic speechperception task, phoneme categorization (Liberman, Harris, Hoffman, & Griffith, 1957). In phoneme-categorization experiments, participants report which of two phonemes (e.g., /g/ or /k/) they heard at the beginning of a syllable. The phoneme is either unambiguous (a clear /g/ or /k/) or ambiguous (a blend between /g/ and /k/). A key finding, called the Ganong effect, is that phoneme categorization is influenced by the lexical status of the syllable (Ganong, 1980). For example, English listeners report more /g/ responses for stimuli along a gift-kift continuum and more /k/ responses for stimuli along a giss-kiss continuum. Mattys and Wiget (2011) found that performing this task in a divided-attention condition (i.e., with a simultaneous visual search task) increased the Ganong effect and decreased perceptual discrimination between phonemes (Fig. 1b). In the present experiment, we replaced the visual search task with a well-established anxiety-inducing manipulation, the 7.5% carbon dioxide (CO 2 ) challenge (Bailey, Argyropoulos, Kendrick, & Nutt, 2005). This procedure, which is used extensively to test novel anxiolytic medications for potential efficacy (Bailey, Kendrick, Diaper, Potokar, & Nutt, 2007), has been shown to elicit cognitive biases that are a core feature of psychological models of anxiety (Garner, Attwood, Baldwin, James, & Munafò, 2011). In the anxiety condition, listeners performed the categorization task and a discrimination task while inhaling air enriched with 7.5% CO 2 . In a control condition, they inhaled air while they performed the tasks.

Effects of 7.5% carbon dioxide inhalation on anxiety and mood in cigarette smokers

Cigarette smoking is associated with elevated risk of anxiety and mood disorder. Using the 7.5% carbon dioxide (CO2) inhalation model of anxiety induction, we examined the effects of smoking status and abstinence from smoking on anxiety responses. Physiological and subjective responses to CO2 and medical air were compared in smokers and non-smokers (Experiment One) and in overnight abstinent and non-abstinent smokers (Experiment Two). CO2 induced greater increases in blood pressure in non-smokers compared with smokers (ps < 0.043), and greater increases in anxiety (p = 0.005) and negative affect (p = 0.054) in non-abstinent compared with abstinent smokers. CO2 increased physiological and subjective indices of anxiety. There were differences across smoking groups indicating that the CO2 inhalation model is a useful tool for examining the relationship between smoking and anxiety. The findings suggested that both acute smoking and acute abstinence may protect against anxious responding. Further investigation is needed in long-term heavy smokers.

Know Your Limits: How does alcohol labelling influence knowledge, attitudes and behaviour?

Alcohol use is a major public health issue. It is associated with over 200 health problems and accounts for almost 6% of all mortality and morbidity (World Health Organisation, 2009). A review of the alcohol trade press showed that the alcohol industry has used alcohol packaging as a promotional tool for decades, and is important in influencing drinking behaviour, brand awareness and even taste (Stead, Angus, Macdonald, & Bauld, 2014). To minimise alcohol’s harms, we can use the same features to reduce consumption instead.