Contemporary Study Li et al. (2013)

Question 1

What did they want to investigate

Answer 1

Investigate involvement of the PCC in heroin dependence.

Question 2

Experimental Group

Answer 2

Exp. group: 14PP from rehab centre in China, withdrawing from Heroin.

Non-cocaine using, right handed age 25-47 and used heroin for 19-182 months.

All had to be heroin free and none had psychiatric illness/head trauma or neurological disease.

Question 3

Control Group

Answer 3

15 PP’s with no history of drug dependence, head injury of psychiatric disorders.

All smoked.

Question 4

Procedure - First Scan

Answer 4

The first scan was a structural MRI scan to identify standard anatomical areas.

Question 5

Procedure - Second Scan

Answer 5

Second was a 5 min resting state fMRI taken as the PP was relaxed

Question 6

Procedure Third Scan

Answer 6

Cue reactivity trial with an fMRI of 490 seconds while 48 images were shown to test cue reactivity.

24 related to heroin, 24 neutral. Shown for 2 secs in a pseudorandom order with a 4-12s gap between each.

Before and after each cue-reactivity run, a self report on 0-10 scale was used to assess craving.

Question 7

Ethics

Answer 7

All PP’s gave written consent and approval obtained from Ethics Committee at Tangdu Hospital.

Question 8

Findings - Craving Scores

Answer 8

Heroin users had significantly higher subjective craving scores than controls after cue induced craving.

Question 9

Conclusion - Craving Scores

Answer 9

Shows that drug related cues are powerful predictors of reward for heroin addicts, and the PCC is linked to neural circuits involved in drug cravings.

Question 10

Strength

Answer 10

High degree of standardisation of procedures.

Each PP saw same heroin-related and neutral images, all for 2 secs.

fMRI scans followed same protocols meaning experience of procedure was identical for every participant.

Internal validity increased as CV controlled.

Question 11

Competing

Answer 11

Some procedures inadequate.

Small sample sizes increased chances of type 1 error like finding a sig result when non existed.
Differences in brain activation between users and controls may not have been genuine.

Question 12

Weakness

Answer 12

Influence of nicotine potentially a CV.

All PP were smokers and researchers claim they accounted for this by doing a test showing no sig difference between them in nic dependence.

Ignores potential influence of an interaction between nicotine and heroin, Kohut shows there is evidence of biochemical interaction between nic and H.

Makes CV as it was a systematic difference between two groups

Question 13

Application

Answer 13

Could lead to improvements in diagnosing brain damage effects in heroin addicts.

Researchers found that abnormal functional connectivity involving the PCC was associated with the extent of a users heroin dependence

If this is reliable then functional connectivity could be used as a biomarker of brain damage in addicts.

fMRI scans similar to ones in study could establish severity of brain damage in heroin users, could be first step in treatment/preventing more damage.