Association Of FNIRS Heart Rate And Variability With Drug Attention Bias Behaviour And Brain Activation In Drug Addicts

Drug addiction and abuse has long been a global problem,and the need for assistance in detoxification and relapse prevention has become a pressing issue.It is important to assess the level of addiction and the physical and mental health of drug abusers before and after withdrawal and rehabilitation.In previous studies,we have found that heart rate and heart rate variability,behaviour and brain activation remain influenced by drug-related stimuli and a tendency to crave drugs after detoxification.There is limited research on the relationship between heart rate and heart rate variability,attentional bias behaviour and brain activation,and there is a lack of comprehensive and objective indicators to assess the level of dependence and physical and psychological impairment in drug users.Therefore,this study aims to demonstrate that drug addiction and craving still exist in drug addicts after withdrawal from different perspectives,and to further investigate whether heart rate and heart rate variability are related to attentional bias behaviour and brain activation,so as to systematically and comprehensively reflect the level of addiction and physical and psychological impairment of drug addicts.It is hoped that heart rate heart rate and variability and brain activation associated with addiction will be added to current diagnostic techniques for assessing addiction as a physiological basis and data support.The present study was conducted on 74 male drug addicts.First,functional near-infrared imaging(fNIRS)was used in conjunction with the dot-probe behavioural experiments to simultaneously measure heart rate and heart rate variability,attentional bias and brain activation in drug addicts in the task state;At the end of the behavioural experiment,the addicts’ level of drug craving was measured using the Obsessive Compulsive Drug Scale.To determine whether there was an attentional bias to drug stimuli and natural rewards,differences in response times were analysed between drug stimuli and detection locations on the opposite and same side of the location(hereafter referred to as incongruent and congruent conditions),and between response times to incongruent and congruent conditions for natural rewards and neutral stimuli,and between response times to incongruent and congruent conditions for the same stimuli.The fNIRS data were all from the DLPFC brain region and brain activation values were obtained by superimposing channel averages on the maximum Hb O2 data for each channel during the 0 ～ 15 s time window for each stimulation condition.Brain activation data were analysed in the same way as the behavioural data described above,i.e.by testing for differences in brain activation values between stimulus conditions.Both heart rate and variability data were obtained from the heart rate component of the fNIRS signal in the DLPFC brain region,where heart rate variability was calculated based on the standard deviation of the heart rate per minute of the detoxified person,i.e.the change in heart rate in time units of minutes.Finally,to investigate whether there is a relationship between heart rate and heart rate variability,attentional bias behaviour and brain activation in drug addicts,phase changes in heart rate and heart rate variability were correlated with attentional bias behaviour and brain activation,respectively.Based on these analyses,the results were as follows:(1)Drug addicts continued to crave drug stimuli after withdrawal(mean scale score 37.43,moderate craving score range 22 ～ 44).(2)Drug stimuli were significantly slower in response to incongruent and congruent conditions compared to neutral stimuli(p < 0.01),whereas natural reward stimuli were only significantly slower in response to incongruent conditions compared to neutral stimuli(p< 0.05).(3)Hb O2 concentrations in the incongruent and congruent conditions of drug stimuli were significantly different from Hb O2 concentrations in the neutral stimulus(p < 0.001;p <0.05);whereas natural reward stimuli were only significantly different from Hb O2 concentrations in the incongruent and neutral stimulus(p< 0.05).(5)There was a significant difference in the correlation between stage changes in heart rate and heart rate variability and attentional bias brain activation under drug stimulation in drug addicts before and after receiving the drug stimulation task(Z =-2.058,p < 0.05).From these results it is concluded that(1)drug stimuli capture attention more than natural reward stimuli in drug abusers who have experienced withdrawal.(2)The stronger attentional bias(cognitive freezing phenomenon)to drug stimuli is reflected in the correlation between phase changes in heart rate variability and brain activation in drug abusers.(3)The phase changes in heart rate and heart rate variability reflect two different states.In the cue-evoked state,the phase change in heart rate reflects an overall change in heart state;the phase change in heart rate variability reflects real-time changes and trends in heart rate.The current study found that drug addicts have an attentional bias in the form of cognitive freezing in response to drug stimuli,and demonstrated a correlation between phase changes in heart rate variability and attentional bias brain activation,which may provide a more comprehensive and systematic physiological basis and data support for future assessment and diagnosis of addiction and physical and mental impairment in drug addicts,as well as a multiperspective combined measurement idea.