Insulin resistance is associated with deficits in hedonic, self-reported cognitive, and psychosocial functional response to antidepressant treatment in individuals with major depressive disorder

Metabolic factors modulate effort-based decision-making in major depressive disorder

BACKGROUND

Abnormalities in effort-based decision-making have been consistently reported in major depressive disorder (MDD). Evidence indicates that metabolic factors, such as insulin resistance and dyslipidemia, which are highly prevalent in MDD, are independently associated with reward disturbances. Herein, we investigate the moderating effect of metabolic factors on effort-based decision-making in individuals with MDD.

METHODS

Forty-nine adults with MDD completed the Effort Expenditure for Rewards Task (EEfRT). Anthropometric and laboratorial parameters were assessed in all participants. We conducted a factor analysis to identify combinations of correlated metabolic variables, and reduce the number of comparisons.

RESULTS

Proxy markers of elevated insulin resistance (OR: 0.816, p < 0.001) and hyperglycemia (OR: 0.898, p = 0.021) were associated with a lower willingness to exert physical effort for rewards in the EEfRT. In contrast, elevated HDL (OR: 1.165, p = 0.004), and elevated non-HDL cholesterol and triglycerides (OR: 1.184, p < 0.001) were associated with increased frequency of hard task choices. These associations were independent of age, sex, depressive symptoms severity and medication use. Computational modeling revealed that the insulin resistance (β = 0.275, p = 0.035) and cholesterol factors (β = 0.565, p < 0.001) were independently associated with increased effort discounting.

LIMITATIONS

Post-hoc analysis using a relatively small sample of convenience.

CONCLUSIONS

Metabolic factors significantly and independently modulated effort-based decision-making in patients with MDD. These results have implications for our understanding of reward disturbances in MDD, and offer insights for further mechanistic investigations.

Insulin resistance, clinical presentation and resistance to selective serotonin and noradrenaline reuptake inhibitors in major depressive disorder

BACKGROUND

The understanding of mechanisms underlying non-response to antidepressants is limited. The latest data highlights the role of insulin resistance (IR) in major depressive disorder (MDD) pathophysiology, presentation, and treatment efficacy. This work aimed to assess IR in MDD and explore the relationships between IR, MDD presentation and non-response to selective serotonin and noradrenaline reuptake inhibitors (SNRI).

METHODS

67 MDD individuals: 36 responsive (MDD T[+]), 31 non-responsive (MDD T[-]) to SNRI and 30 healthy controls were recruited. The treatment response criteria were: Clinical Global Impression Scale-Improvement score of 1 or 2 after ≥ 8 weeks of treatment. Participants were assessed by physician and self-report tools measuring depression, anhedonia, anxiety, bipolarity, sleep quality. Blood samples were collected to assess fasting glucose and insulin levels and calculate HOMA-IR (homeostasis model assessment of insulin resistance).

RESULTS

MDD T[-] vs. MDD T[+] had significantly higher body mass index, insulin levels, and HOMA-IR. MDD T[-] presented higher levels of depressed mood, appetite/weight changes, loss of interest, energy, overall depressive symptoms, and sleep impairment; some evaluations suggested higher anhedonia and anxiety in MDD T[-] vs. MDD T[+]. Insulin and IR were weakly but significantly correlated with the severity of psychomotor symptoms, energy level, thoughts of death/suicide, self-criticism, appetite/weight, depressed mood symptoms, sleep problems. IR was weakly but significantly correlated with anhedonia.

CONCLUSION

IR appears to be linked to depressive symptoms characteristic of the "metabolic" MDD subtype, such as psychomotor changes, energy level, anhedonia, sleep problems, appetite/weight changes, state and trait anxiety, sleep quality, and non-response to SNRI.

Insulin Resistance, Temperament and Personality Traits Are Associated with Anhedonia in a Transdiagnostic Sample

Anhedonia constitutes a core symptom of major depressive disorder (MDD) mediating the ultimate goal of MDD treatment: functional remission. Anhedonia is also present in other clinical populations, including patients with chronic pain. Recent data links anhedonia to insulin resistance (IR). Some researchers have underlined a different dimension of anhedonia as a temperament/personality trait. The objective of this post-hoc analysis was to explore the links between anhedonia (main outcome) and (1) IR, (2) temperamental, personality, and schizotypy traits (exposures). The study population included patients with MDD, fibromyalgia, and healthy controls. Participants were split into groups: (1) insulin resistant (IR[+] n = 69, HOMA-IR ≥ 2.1) and (2) insulin sensitive (IR[-] n = 69, HOMA-IR < 2.1). Anhedonia was significantly higher in the IR[+] group than the IR[-] group. IR was a predictor of higher anhedonia levels. IR[+] vs. IR[-] participants showed higher levels of anxiety and lower levels of hyperthymic affective temperaments, as well as conscientiousness and emotional stability personality traits. Depressive, irritable, and anxious temperaments, cognitive disorganization, and introvertive anhedonia positively predicted anhedonia, while hyperthymic temperament, conscientiousness, extraversion, and emotional stability traits negatively predicted anhedonia. IR partially mediated the relationship between depressive temperament and anhedonia. In sum, IR, affective temperaments, and personality traits are predictors of anhedonia.

Consolidating evidence on the role of insulin resistance in major depressive disorder

PURPOSE OF REVIEW

The circular interactions between type 2 diabetes (TMD2) and major depressive disorder (MDD) are well documented but the understanding of their mechanisms has only recently gained more clarity. Latest research indicates, that the association between TMD2 and MDD is largely mediated by insulin resistance (IR).

RECENT FINDINGS

A metabolic subtype of MDD can be distinguished from other MDD subpopulations, that is characterized by predominantly atypical clinical presentation, IR and different responsiveness to antidepressant interventions. IR is a predictor of nonresponse to some antidepressants. The IR seems to be a state-marker of clinical or subclinical depression and the relationship between IR and MDD varies between sexes and ethnicities. Insulin has a direct impact on the monoaminergic systems known to underlie MDD symptoms: serotoninergic and dopaminergic, which are dysregulated in IR subjects. Several trials assessed the efficacy of insulin-sensitizing drugs in MDD with mixed results for metformin and more consistent evidence for pioglitazone and lifestyle intervention/physical activity.

SUMMARY

Recently published data suggest a significant role of IR in the clinical presentation, pathophysiology and treatment response in MDD. Further research of IR in MDD and integration of existing data into clinical practice are needed.

The association between insulin resistance and depressive symptoms - A national representative cross-sectional study

OBJECTIVE

Increasing evidence suggests a positive association between insulin resistance (IR) and depression. However, whether sex-or body mass index-specific differences exist remains controversial, and only few studies have analyzed specific symptom domains. Thus, the present study aimed to analyze the association between IR and depressive symptom domains and to clarify the effects of sex and body mass index.

METHODS

The study sample comprised 4007 participants, aged 19-79, from the Korea National Health and Nutrition Examination Study 2020. Participants completed health interviews and examinations, providing data on circulating insulin and glucose levels, the Patient Health Questionnaire-9 (PHQ-9), and related covariates. IR was calculated using the homeostasis model assessment of insulin resistance. Associations between IR and PHQ-9 were analyzed using negative binomial regression with adjustments for the complex survey design.

RESULTS

The association between log-transformed IR and PHQ-9 total scores was statistically significant (incidence rate ratio [IRR] = 1.17, 95% confidence interval [CI] = 1.07-1.29, p = 0.001). Only body mass index specific differences were statistically significant, as the association was only significant in those without obesity (IRR = 1.21, 95% CI = 1.06-1.38, p = 0.005). IR was associated with cognitive/affective (IRR = 1.23, 95% CI = 1.08-1.41, p = 0.002) and somatic (IRR = 1.14, 95% CI = 1.04-1.25, p = 0.005) depressive symptom domains. Sensitivity analyses revealed similar results.

CONCLUSIONS

IR was positively associated with cognitive/affective and somatic depressive symptoms in non-obese individuals.

THINC-Integrated Tool (THINC-it): A Brief Measurement of Changes in Cognitive Functioning and Its Correlation with the Life Quality of Patients with Schizophrenia and Related Disorders-A Pilot Study

BACKGROUND

This pilot study aimed to assess patients' cognitive functioning with the Polish version of the THINC-it tool and to analyze its association with self-reported quality of life (QOL).

METHODS

Twenty-one patients (mean age: 37.8 ± 10.4) were assessed at baseline and after six weeks of a standard therapeutic outpatient program. Participants completed the World Health Organization QOL Questionnaire (WHOQOL-BREF) and the THINC-it tool at both visits. The tool consists of tasks evaluating working memory (SYMBOL CHECK), attention (SPOTTER), executive functions (TRIALS), and cognitive skills (CODEBREAKER).

RESULTS

During the second visit, patients showed significant improvements in mean latency of correct responses of SPOTTER: p = 0.021, Cohen's d = 0.38 and in the Physical health domain: p = 0.007, Cohen's d = 0.37. The number of correct responses for CODEBREAKER was positively associated with the Physical health domain at visit 1 (r = 0.53, p = 0.014) and visit 2 (r = 0.42, p = 0.058). The number of correct responses at SYMBOL CHECK was positively related to QOL in the Environment domain only at visit 2 (r = 0.45, p = 0.042).

CONCLUSIONS

These results suggest the THINC-it tool has utility as a cognitive measure in adults with schizophrenia in both clinical and research settings.

Changes in insulin resistance following antidepressant treatment mediate response in major depressive disorder

BACKGROUND

Insulin resistance (IR) is a potential predictor of antidepressant treatment response.

AIMS

We assess changes in IR after antidepressant treatment and whether these changes have any effect on treatment response. Also, to see whether changes in IR mediates relationship between C-reactive protein (CRP) and antidepressant efficacy.

METHODS

This is a secondary analysis of an 8-week, open-label clinical trial with 95 adults experiencing a major depressive episode. Response to vortioxetine was measured using the Montgomery-Åsberg Depression Rating Scale (MADRS). Generalized estimating equation models were utilized for this intent-to-treat analysis.

RESULTS

When adjusted for age, sex, and body mass index, there was a significant increase in IR following treatment in the overall sample (p = 0.035). This finding was detected in treatment non-responders (p = 0.019), whereas it was not observed in responders (p = 0.329). Mediation analysis revealed that change in IR during treatment was responsible for change in MADRS as well as the relationship between baseline CRP and treatment response.

CONCLUSIONS

Exacerbation of IR during antidepressant treatment mediated non-response. Conversely in treatment responders IR reduced. Like previous studies, baseline CRP moderated treatment response. This relationship was also mediated by changes in IR. These findings further elucidate the role of IR in terms of antidepressant response as well as potentially explain inflammation's relationship with the latter.