Li et al 2013 - Contemporary Study Flashcards
What were the aims of Li et al?
To investigate whether chronic heroin use is associated with craving related changes in the functional connectivity of the posterior cingulate cortex (PCC) of heroin addicts
To see if there was a relationship between dysfunctional connectivity of the PCC and heroin dependence.
Describe the sample of Li et al
14 male ppts
All aged between 18 and 50
All had been addicted to heroin for an average of 89.3 months
Heroin addiction was diagnosed with DSM IV
All addicts came from a drug rehab centre in China
All addicts were in the detoxification stage, measured through heroin in urine
All were clean from heroin
All not using any other illicit drug
All had to be right-handed
Excluded if they had any past/current psychiatric illness, neurological signs or disease, head trauma, cardiovascular or endocrine disease, claustrophobia, any magnetic objects in their body or any illness that would prevent an MRI scan
15 control ppts who were healthy and had no drug dependency (other than nicotine), head injuries or psychiatric disorders
Describe the procedure of Li et al
Each ppts had 2 scans: one in resting and one during the heroin cue reactivity test
During the first scan, they were told to focus on the crosshair, relax and not move
After a practice run of 10 seconds, ppts saw 24 heroin-related pictures and 24 non-heroin-related pictures for 2 seconds with the cross hair for 4-12 seconds between each picture.
Craving was assessed before and after the pictures were shown using a visual analogue scale
eg 1 = no craving and 10 = a lot of craving
Drug-related activity scans vs neutral scans were compared for each group
Differences in nicotine dependence were checked using a Wilcoxon rank sum test
Describe the results of Li et al
Heroin addicts’ subject craving increased by 0.98 before and after the cue-induced craving task.
Heroin addicts had significantly higher subject cravings after the task than non-addicts.
Heroin addicts had more activity in the bilateral PCC when looking at the heron cues
Describe the conclusions of Li et al
The connectivity of the PCC and duration of heroin were positively correlated, suggesting these areas of the brain are associated with heroin dependence and are involved in craving.
However, we can not say heroin use causes changes within the brain as they didn’t look at this in this study
Evaluate the generalisability of Li et al
Small sample size - 29 ppts
Androcentric - only male ppts
Ethnocentric - all from rehab centre in China
China is quite authoritarian, so ppts may not be truthful about craving as they may feel that’s what they should say in a rehab centre
Evaluate the reliability of Li et al
Standardised procedure - all saw 48 pictures and cross hair for the same amount of time etc
Controls - excluded things that could have affected results such as head injury, psychiatric illness, other illicit drugs etc
Evaluate the application of Li et al
We now know to provide care plans when sending addicts back into society in order to shield them from cues that could cause relapse
Evaluate the validity of Li et al
Ecological validity - the rehab centre is a familiar setting
Task validity - MRI scans are not natural behaviour
Demand characteristics - Can’t change MRI results, but craving scale is self-report data and so may not be accurate (authoritarian culture may affect this)
Evaluate the ethics of Li et al
Protection from harm - all the exclusions prevent harm being caused to the ppts
e.g. magnetic items mean they can’t do an MRI scan as this could rip objects out of their body
