The research team, led by Şafak Yalçin Şahiner of Ankara University, enrolled 101 adults meeting DSM-5 criteria for heroin use disorder at a single treatment center in Türkiye. Participants were divided into two clinically distinct groups: 52 patients in sustained remission under outpatient follow-up for at least three months, and 49 patients undergoing active detoxification for acute withdrawal. The sample was predominantly male, with a mean age of 33 years, and the two groups were well matched on sociodemographic variables including age, body mass index, education, employment, and smoking status.

The investigators measured two complementary blood markers. The first is thiol-disulfide homeostasis, the dynamic equilibrium between thiol groups carried on cysteine residues and the disulfide bonds they form under oxidizing conditions. Because most plasma thiols reside on human serum albumin, this protein serves as the largest circulating antioxidant reservoir and a convenient window into systemic redox status. The second marker is ischemia-modified albumin, or IMA, which arises when the N-terminal region of albumin loses its transition-metal binding capacity under hypoxic and acidic conditions. Originally described in cardiac ischemia, IMA has emerged as a broader composite indicator of oxidative stress, ischemia, and inflammation, with elevated levels reported in several psychiatric conditions.

Biochemically, the results were striking in their uniformity. Native thiol, total thiol, disulfide, all three derived ratios, and IMA showed no statistically significant differences between the remission and detoxification groups. Median total thiol was 320.93 μmol/L in remission and 320.30 μmol/L in detoxification, while median IMA was 0.757 and 0.792 absorbance units respectively. Effect sizes for these comparisons were small, and the pattern remained unchanged after statistical adjustment for medication use, recent non-heroin substance use, duration of heroin use, and age at first treatment. A sensitivity analysis restricted to patients without recent non-heroin substance use produced the same null result.

In sharp contrast, the psychometric measures separated the two phases dramatically. Patients in detoxification scored markedly higher on depression, anxiety, anger, somatic symptoms, suicidal ideation, psychosis, sleep disturbance, dissociation, and substance craving, all at p ≤ 0.001. Median craving scores were 19 out of a possible 30 in detoxification compared with 0 in remission. Conversely, the remission group showed significantly higher healthy-lifestyle behavior and healthy nutrition attitude scores. This clear dissociation between clinical symptom burden and peripheral redox markers suggests that changes in emotional and substance-related symptom severity across treatment phases are not necessarily accompanied by parallel shifts in these blood-based biochemistry measures.

Exploratory correlation analyses across the whole sample revealed meaningful associations between the biomarkers and psychological variables. IMA correlated positively with depression (r = 0.254) and craving (r = 0.209), supporting the conceptualization of IMA as a composite marker of systemic oxidative, ischemic, and inflammatory stress rather than a single organ-specific mechanism. Meanwhile, the disulfide-to-thiol ratios correlated negatively, and the native thiol to total thiol ratio positively, with healthy-lifestyle and nutrition-attitude scores, indicating a redox balance shifted toward the antioxidant side in patients reporting healthier behaviors. None of these correlations survived Bonferroni correction for multiple comparisons, so the authors present them as hypothesis-generating findings requiring confirmation in larger samples.

Hierarchical multiple regression models failed to identify any significant clinical predictor of total thiol or IMA. Baseline models including age, body mass index, alcohol use, duration of heroin use, daily heroin amount, medication use, and time since last heroin use explained little variance. Adding depression, craving, and healthy lifestyle behavior in a second block did not significantly improve the models. These findings indicate that the determinants of these markers in heroin use disorder are not accounted for by simple parameters of substance exposure or demographic profile, and may instead depend on a complex interplay of symptoms, inflammation, nutrition, and pharmacotherapy that requires larger samples and wider covariate sets to model adequately.

The authors emphasize that their null biomarker findings should be considered informative rather than merely negative. A companion case-control study from the same group had reported differences in thiol-disulfide ratios and IMA between patients with heroin use disorder and healthy controls. The present results suggest that once the disorder is established, transitioning between acute withdrawal and stabilized remission does not in itself produce a measurable shift in systemic thiol chemistry, and that redox imbalance may remain altered during early-to-intermediate remission with a profile similar to that observed during active exposure. This contrasts with bipolar disorder, where the same markers changed from acute mania to early remission, suggesting that the phase sensitivity of redox markers may be disorder-specific.

Several confounding factors warrant caution in interpretation. Smoking was nearly universal in both groups, affecting 98 percent of participants, and cigarette smoke is known to deplete circulating thiol pools, potentially masking subtle phase-specific differences. Maintenance buprenorphine-naloxone was far more frequent in the remission group, and while medication-adjusted analyses yielded the same overall pattern, medication use itself showed a statistically significant relationship with disulfide levels. The cross-sectional design cannot establish causality, the sample size limited statistical power, and the absence of a healthy control group means that neither group could be compared against reference values from a healthy population.

The study’s central conclusion is that within heroin use disorder, peripheral redox and ischemia markers appear to function as continuous correlates of clinical state rather than as categorical indicators of treatment phase. IMA, in particular, may reflect an oxidative and inflammatory component of mood regulation and craving, a finding consistent with clinical trials showing that the thiol-based antioxidant N-acetylcysteine reduces craving across various substance use disorders. The authors call for pre-registered, longitudinal, and sex-balanced studies incorporating healthy control groups and long-term abstinence follow-up to track the full biological recovery process in opioid dependence.

Subject of Research: A comparative evaluation of thiol/disulfide homeostasis and ischemia-modified albumin levels in patients with heroin use disorder in remission and detoxification

Article Title: A comparative evaluation of thiol/disulfide homeostasis and ischemia-modified albumin levels in patients with heroin use disorder in remission and detoxification

Article References: Yalçin Şahiner, Ş., Baysal, D., Vayisoğlu, T., Uçar Hasanli, Z., Neşelioğlu, S., Avcioğlu, G., Polat, H., Serav İlhan, R., & Erel, Ö. (2026). A comparative evaluation of thiol/disulfide homeostasis and ischemia-modified albumin levels in patients with heroin use disorder in remission and detoxification. Frontiers in Behavioral Neuroscience, 20, Article 1933257. https://doi.org/10.3389/fnbeh.2026.1933257

Image Credits: AI Generated

DOI: 10.3389/fnbeh.2026.1933257

Keywords: comparative, evaluation, thiol, disulfide, homeostasis, ischemia-modified, albumin, levels, patients, heroin, disorder, remission