Emotion recognition during cocaine intoxication

Abstract

Chronic or repeated cocaine use has been linked to impairments in social skills. It is not clear whether cocaine is responsible for this impairment or whether other factors, like polydrug use, distort the observed relation. We aimed to investigate this relation by means of a placebo-controlled experimental study. Additionally, associations between stressor-related activity (cortisol, cardiovascular parameters) induced by the biological stressor cocaine, and potential cocaine effects on emotion recognition were studied.

Twenty-four healthy recreational cocaine users participated in this placebo-controlled within-subject study. Participants were tested between 1 and 2 h after treatment with oral cocaine (300 mg) or placebo. Emotion recognition of low and high intensity expressions of basic emotions (fear, anger, disgust, sadness, and happiness) was tested.

Findings show that cocaine impaired recognition of negative emotions; this was mediated by the intensity of the presented emotions. When high intensity expressions of Anger and Disgust were shown, performance under influence of cocaine ‘normalized’ to placebo-like levels while it made identification of Sadness more difficult. The normalization of performance was most notable for participants with the largest cortisol responses in the cocaine condition compared to placebo.

It was demonstrated that cocaine impairs recognition of negative emotions, depending on the intensity of emotion expression and cortisol response.

Introduction

The latest report on drug abuse in Europe shows that cocaine is the most commonly used illicit stimulant, with a last year prevalence of 1.7% in the young adult (15–34 yrs.) population. The reported preferred route of administration is nasal, accounting for 64%, and the least common was oral, good for 2% (EMCDDA, 2014). Cocaine has been demonstrated to increase cardiovascular parameters (blood pressure, heart rate) and subjective effects (e.g. ‘rush’) after intake, with peak effects immediately after insufflation and 1 h after oral ingestion, followed by a progressive decline of effects thereafter (Couper and Logan, 2004, Rush et al., 1999). The effects after oral administration coincide with blood plasma levels that peak 1 h after ingestion of cocaine while those after insufflation peak at 30 min when the effects are already subsiding (Couper and Logan, 2004).

Chronic or repeated cocaine use has been linked with impairments in various cognitive domains (e.g. attention, memory, psychomotor performance) (Spronk et al., 2013) but also in social skills (e.g. (Hulka et al., 2014; Preller et al., 2014a, Preller et al., 2014b)). It has been shown that cocaine users have less emotional engagement in social interactions (Preller et al., 2014a) and behave less ‘altruistic’, as demonstrated by a greater concern with their own monetary gain when interacting with another person, compared to controls (Hulka et al., 2014). Diminished social reward processing was suggested as explanation for this impairment in social interaction (Preller et al., 2014a). Another important contributing factor to the latter could be empathy (emotional, cognitive) as this is underlying social interaction (Adolphs, 2003, Rameson and Lieberman, 2009). Recreational and chronic cocaine users have been shown to display less emotional empathy compared to controls. Younger age of onset of use was associated with a pronounced reduction of empathy. Chronic users also showed more errors in mental perspective taking (Preller et al., 2014b). The latter can be seen as part of cognitive empathy, together with e.g. emotion recognition (Blair, 2005). Findings on emotion recognition in cocaine users have not been consistent. Whereas Kemmis et al. (2007) showed that emotion recognition of basic emotions (‘cognitive empathy’) was disturbed in cocaine users as compared to controls, others failed to demonstrate a defect in emotion recognition of basic and complex emotions (Kemmis et al., 2007, Preller et al., 2014b, Woicik et al., 2009). Woicik et al. (2009) ascribed these contradictory findings in basic emotion recognition to differences in drug history of participants. Where Kemmis et al. (2007) included polydrug cocaine users; Woicik et al. (2009) only included cocaine users without a lifetime polydrug history. Woicik et al. (2009) therefore suggested that drugs other than cocaine might be underlying these deficits in emotion recognition. They concluded that the association between cocaine use and emotion recognition remains to be determined. To circumvent methodological issues associated with this type of studies (e.g. between group differences and polydrug use influences) and to determine a causal relation between cocaine use and emotion recognition, a placebo-controlled experimental within-subject study will be conducted.

Cocaine can be regarded as a biological stressor, as administration leads to elevated cortisol levels (Heesch et al., 1995). Besides effects on cortisol, stressors are known to affect cardiovascular parameters and engage more heavily specific parts of the limbic system, which plays a role in emotion processing (Dedovic et al., 2009, Seifritz et al., 1996, Shirtcliff et al., 2009). In the present study it will be investigated whether the cocaine-induced effects on cortisol and cardiovascular parameters are associated with potential effects on emotion recognition.