Neurocognitive Functions After 6-Month Buprenorphine (Naloxone)-Based Opioid Agonist Maintenance Treatment: A Controlled Prospective Study

BACKGROUND

Medications for opioid use disorder (OUD) may influence neurocognitive functions. Inadequate power, confounders, and practice effects limit the validity of the existing research. We examined the change in cognitive functions in patients with OUD at 6-month buprenorphine (naloxone) posttreatment and compared the cognitive performance of the buprenorphine-treated group with control subjects.

METHODS

We recruited 498 patients with OUD within a week of initiating buprenorphine. Assessments were done twice-at baseline and 6 months. Those abstinent from illicit opioids and adherent to treatment (n = 199) underwent follow-up assessments. Ninety-eight non-substance-using control subjects were recruited from the community. The neurocognitive assessments comprised the Wisconsin Card Sorting Test, Iowa Gambling Task, Trail-Making Tests A and B (TMT-A and TMT-B), and verbal and visual N-Back Test. We controlled for potential effect modifiers.

RESULTS

Twenty-five of the 32 test parameters significantly improved with 6 months of buprenorphine treatment; 20 parameters withstood corrections for multiple comparisons (P < 0.001). The improved test domains spread across cognitive tests: Wisconsin Card Sorting Test (perseverative errors and response, categories completed, conceptual responses), TMTs (time to complete), verbal and visual N-Back Tests (hits, omission, and total errors). After treatment, OUD (vs control subjects) had less perseverative response and error (P < 0.001) and higher conceptual response (P = 0.004) and took lesser time to complete TMT-A (P < 0.001) and TMT-B (P = 0.005). The baseline neurocognitive functions did not differ between those who retained and those who discontinued the treatment.

CONCLUSION

Cognitive functions improve in patients with OUD on buprenorphine. This improvement is unlikely to be accounted for by the practice effect, selective attrition, and potential confounders.

Neurocognitive Dysfunctions in People with Concurrent Cannabis Use and Opioid Dependence: A Cross-Sectional, Controlled Study

Cannabis and opioid co-dependence is independently associated with cognitive impairments. We examined neurocognitive dysfunctions in people with concurrent opioid dependence with cannabis dependence (OD+CD) or cannabis use (OD+CU) compared to those with only opioid dependence (OD) and healthy controls (HC). We selected adult participants, any sex, who met the diagnosis of OD (N = 268), OD+CU (N = 58), and OD + CD (N = 115). We recruited 68 education-matched HC. We administeredStandard progressive matrices (SPM), Wisconsin card sorting test (WCST), Iowa gambling task (IGT), Trail making tests A and B (TMT), and verbal and visual working memory 1-, 2-backtests. 496 (97.5%) were men, and 13 (2.5%) were women. In WCST, OD and OD+CD had significantly higher non-perseverative errors than HC. OD+CD group completed significantly lesser categories than HC. In verbal working memory 2-back, HC scored significantly fewer errors than OD and OD +CD. All patient groups, OD, OD+CU, and OD+CD, scored higher commission errors than HC in visual working memory 1-back. OD and OD+CD scored higher commission and total errors than the controls. OD+CU showed lesser error score than HC in TMT B. Cannabis and opioid co-dependence contribute to cognitive impairments, especially in working memory and executive functions.

Effectiveness of buprenorphine (naloxone) for opioid dependence does not differ across opioid categories: a retrospective cohort study from India

We aimed to examine whether treatment retention, abstinence, and adherence to buprenorphine-naloxone (BNX) differ among individuals with opioid dependence (OD) across three common categories of opioids- heroin, opium, and low-potency pharmaceutical. In a retrospective cohort study, we analyzed outpatient treatment records from March 2020 through February 2022. Opioid category was determined by lifetime and current opioid use. We defined treatment retention as weeks of uninterrupted clinic attendance. Abstinence and BNX adherence were calculated by weeks of extra-medical opioid-negative and buprenorphine-positive urine screening from treatment initiation. Four-hundred-thirteen patients were eligible; 406 (98.3%) were included in the final analysis. Two-hundred-ninety (71.4%) patients were dependent on heroin; 66 (16.3%) were natural opioid dependent, and 50 (12.3%) were dependent on low-potency pharmaceutical opioids. BNX effectiveness in treatment retention, abstinence, and adherence did not differ in patients dependent on heroin, natural, and low-potency pharmaceutical opioids. Patients on ≥8 mg daily BNX had better retention and adherence than those on <8 mg daily. Patients from lower socioeconomic status (SES) had higher odds of retention, abstinence, and adherence than those from upper/middle SES. Treatment outcomes on BNX did not differ across opioid categories. However, BNX should be dosed adequately.

Heroin use and neuropsychological impairments: comparison of intravenous and inhalational use

BACKGROUND AND OBJECTIVES

Injection and inhalational heroin use are associated with different levels of brain exposure to heroin and its metabolites and differences in the severity of dependence, which might lead to differential impacts on neuropsychological functions. We examined the difference and the magnitude of difference in the neuropsychological functions between inhalational and injection heroin-dependent subjects and also compared them with healthy controls.

METHODS

The study sample comprised three groups: 73 subjects with injection heroin dependence, 74 with inhalational heroin dependence, and 75 healthy controls (HC). We excluded patients with HIV, head injury, epilepsy, and severe mental illness. Neuropsychological assessments were done by Standard Progressive Matrices, Wisconsin Card Sorting Test (WCST), Iowa Gambling Task, Trail-Making Tests A and B (TMT), and Verbal and Visual Memory 1 and 2 Backtests (NBT). We estimated independent effects of the groups on various neuropsychological test parameters, adjusted for age and duration of dependence.

RESULTS

In the WCST, the inhalational heroin-dependent group took more trials to complete the first category and had higher scores in the failure to maintain set than controls. The intravenous group had higher total errors than controls in verbal working memory tests and Visual Working Memory 2 Backtest. This group scored higher commission errors in the Verbal 2 Backtest than the controls. The two groups of heroin users differed in failure to maintain set and Verbal Working Memory 2 Backtests. The effect sizes of the group differences were modest.

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

Either route of heroin use is associated with cognitive impairments; inhalational and injection use involve different cognitive domains.