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Anhedonia is defined as a diminished ability to experience interest or pleasure, and is a critical psychopathological dimension of major depressive disorder (MDD). The purpose of the current systematic review is to evaluate the therapeutic efficacy of pharmacological treatments on measures of anhedonia in adults with MDD. Electronic databases Cochrane Library (CENTRAL), Ovid MEDLINE, PubMed, PsycINFO, and Google Scholar were searched from inception to June 1, 2018 for longitudinal studies utilizing pharmacotherapy for the treatment of anhedonia in patients with MDD. A total of 17 eligible studies were identified (i.e., evaluated the effects of pharmacotherapy on a measure of anhedonia). Among the identified studies, the efficacy of 14 different pharmacotherapies on measures of anhedonia were evaluated, including melatonergic agents (i.e. agomelatine), monoaminergic agents (i.e. moclobemide, clomipramine, bupropion, venlafaxine, fluoxetine, amitifadine and levomilnacipran, escitalopram, and sertraline), glutamatergic agents (i.e., ketamine and riluzole), stimulants (i.e., methylphenidate), and psychedelics (i.e., psilocybin). Based on the available evidence, most antidepressants demonstrated beneficial effects on measures of anhedonia as well as the other depressive symptoms. Only escitalopram/riluzole combination treatment was ineffective in treating symptoms of anhedonia in MDD. Continued research is warranted to further support the efficacy of mechanistically-distinct antidepressants in treating symptoms of anhedonia in MDD. Future research should also aim to parse out the heterogeneous effects of different pharmacotherapies on anhedonic symptoms. • Majority of antidepressants do not show pronounced collinear improvements in anhedonia and other depressive symptoms. • Therapies targeting melatonergic receptors and circadian rhythm imbalances are more direct targets for treating anhedonia. • Ketamine may be faster acting of anti-anhedonia due to direct effect on mitochondrial energy metabolism. [ABSTRACT FROM AUTHOR]

Sirtuins are NAD + -dependent histone deacetylases that play essential roles in cell survival, energy metabolism, inflammation, and aging; therefore, sirtuins are potential therapeutic targets in the treatment of type 2 diabetes, cancer, inflammatory and metabolic disorders, and neurodegenerative diseases. Available evidence provides the basis for hypothesizing that sirtuins 1, 2, and 3 (SIRT1, SIRT2, and SIRT3) may have a mechanistic role subserving mood disorders (i.e. downregulation) and associated co-morbidity (e.g. metabolic disorders). Specifically, the domains of general cognitive processes, as well as cognitive emotional processing may be particularly relevant to sirtuin physiology. Given the role of sirtuins in the perpetuation of circadian rhythmicity, and evidence of dysfunctional circadian cycling in mood disorders, sirtuins may be an underlying etiological factor that links circadian rhythm functionality with mood disorders. Caloric restriction, and caloric restriction mimetics (e.g. resveratrol) are all capable of upregulating sirtuin isoforms implicated in stress response syndromes. Repurposing existing treatments and/or discovery of novel agents capable of modulating sirtuin physiology may represent genuinely novel approaches for trans-diagnostic domains affected in mood disorders and other brain-based illnesses. [ABSTRACT FROM AUTHOR]

Fibromyalgia (FM) is a condition associated with chronic pain in muscles and soft tissues. Extant literature has demonstrated an association between FM, mood symptoms and suicidal behaviour. This systematic review aims to synthesize available literature assessing the prevalence of suicidality in FM populations and qualitatively review the included articles. PsycINFO, Google Scholar and PubMed databases were systematically searched for studies published from database inception to 15 February 2020. Studies were included that assessed FM as a primary or co-primary disease condition, as well as an assessment of suicidal behaviour (suicidal ideations (SI), suicide attempts (SA) and death by suicide (SC)). The quality of the studies was assessed using the Newcastle-Ottawa Scale. 699 unique articles were reviewed for eligibility. Data were derived from nine studies (cross-sectional: k = 5; retrospective cohort: k = 4) that assessed suicidal behaviour in FM participants (SI: k = 5, SC: k = 3, SA: k = 3). Four studies assessing SI found elevated rates of SI among FM participants. Three studies found elevated risk for SC and three studies found increased SA in FM participants relative to the general population. In two studies, this association was no longer significant after adjusting for depression and other psychiatric comorbidities. Preliminary findings suggest that FM is associated with significantly higher risks for SI, SA and SC compared to the general population. There may be unique risk factors underlying suicidal behaviour in FM patients and the interaction between FM and other known risk factors (i.e., mental illness) require further investigation. • Fibromyalgia participants are at an increased risk of attempting suicide. • Suicidal ideation is elevated among participants with fibromyalgia. • Suicide mortality rates are higher in fibromyalgia than the general population. • Depression is highly comorbid with fibromyalgia. [ABSTRACT FROM AUTHOR]

Early symptomatic improvement with monoamine-based antidepressants is predictive of treatment response. The objective of this study was to determine if early symptomatic improvements with intravenous (IV) ketamine predicted treatment response to an acute course of four infusions. 134 adults with treatment resistant depression (TRD) received four ketamine infusions over one to two weeks. Depressive symptoms were measured using the Quick Inventory for Depressive Symptomatology Self-Report 16 (QIDS-SR 16) at baseline and post-infusions 1, 2, 3, and 4. Early improvement was defined as ≥20% reduction in QIDS-SR 16 scores after the first or second infusion. Linear models were used to determine whether early improvement was associated with post-infusion 4 QIDS-SR 16 scores after controlling for baseline characteristics. Early improvement post-infusion 1 (β = −3.52, 95% BCa CI [−5.40, −1.78]) and 2 (β = −3.16, 95% BCa CI [−5.75, −1.59]) both significantly predicted QIDS-SR 16 scores post-infusion 4. Early improvers had significantly lower QIDS-SR 16 scores at post-infusion 4 (post-infusion 1 improvers: M = 9.8, SD = 4.5; post-infusion 2 improvers: M = 10.6, SD = 5.7) compared to non-early improvers (post-infusion 1 non-improvers: M = 13.7, SD = 5.8; post-infusion 2 non-improvers: M = 14.1, SD = 5.3) when controlling for baseline characteristics. The majority (58%) of individuals who did not improve post-infusions 1 or 2 still experienced an antidepressant response or partial response (≥20% reduction in QIDS-SR 16) post-infusion 4. This is a post-hoc analysis of an open-label study. Early improvement was associated with greater antidepressant effects following a course of four ketamine infusions. However, individuals who did not show early improvements still had a high likelihood of experiencing clinically significant symptom reduction after the fourth infusion, suggesting that completing four infusions, regardless of early symptom changes, is appropriate and merited. • Early symptom improvement was associated with greater antidepressant effects following four ketamine infusions. • ~40% of individuals with early improvement responded to the full treatment course versus 14–19% in non-early improvers. • 58% of individuals who did not experience early improvement experienced a partial to full response after the fourth infusion. [ABSTRACT FROM AUTHOR]

Numerous pharmacological treatments for mood disorders are currently available; however, rates of treatment resistance, relapse and recurrence remain high. Therefore, novel treatments acting outside of the conventionally targeted monoamine system are urgently needed to improve patient outcomes. Emerging and converging evidence suggests that immune dysfunction, oxidative stress, impaired cerebral blood flow (CBF) and decreased neurotrophic factors all contribute to mood disorder pathophysiology and are therefore treatment targets of interest. Pentoxifylline (PTX) is a phosphodiesterase inhibitor with potent anti-inflammatory and antioxidant effects, with additional pleiotropic effects that lead to improved CBF and increases in brain derived neurotrophic factor (BDNF) levels. The direct effect of non-specific phosphodiesterase inhibition may also improve alertness and cognitive function through enhancing second messenger systems. Replicated preclinical studies have demonstrated antidepressant-like effects in animal models. Small preliminary clinical trials have demonstrated promising results for antidepressant and procognitive effects, however, have yet to be replicated in larger mood disorder samples. Only one randomized clinical trial (RCT) specifically assessed the effects of adjunctive PTX in major depressive disorder (MDD), showing clinically and statistically significant antidepressant effects compared to placebo. No studies have assessed PTX in bipolar disorder (BD), where inflammation and altered CBF have also been strongly implicated. Taken together, PTX presents as a promising pleiotropic agent with several potential novel mechanisms of action meriting further evaluation in clinical trials to evaluate target engagement, antidepressant, procognitive and mood stabilizing effects. • Immune dysfunction, oxidative stress and impaired cerebral blood flow are observed in mood disorders • Pentoxifylline (PTX) is a phosphodiesterase inhibitor with anti-inflammatory, antioxidant, and neurotrophic effects • PTX may improve cerebral blood flow • Preclinical and preliminary clinical data suggests that PTX may have antidepressant properties [ABSTRACT FROM AUTHOR]