Changes in platelet markers of obsessive-compulsive patients during a double-blind trial of fluvoxamine versus clomipramine

Is there a relationship between morphological and functional platelet changes and depressive disorder?

BACKGROUND

Blood platelets, due to shared biochemical and functional properties with presynaptic serotonergic neurons, constituted, over the years, an attractive peripheral biomarker of neuronal activity. Therefore, the literature strongly focused on the investigation of eventual structural and functional platelet abnormalities in neuropsychiatric disorders, particularly in depressive disorder. Given their impact in biological psychiatry, the goal of the present paper was to review and critically analyze studies exploring platelet activity, functionality, and morpho-structure in subjects with depressive disorder.

METHODS

According to the PRISMA guidelines, we performed a systematic review through the PubMed database up to March 2020 with the search terms: (1) platelets in depression [Title/Abstract]"; (2) "(platelets[Title]) AND depressive disorder[Title/Abstract]"; (3) "(Platelet[Title]) AND major depressive disorder[Title]"; (4) (platelets[Title]) AND depressed[Title]"; (5) (platelets[Title]) AND depressive episode[Title]"; (6) (platelets[Title]) AND major depression[Title]"; (7) platelet activation in depression[All fields]"; and (8) platelet reactivity in depression[All fields]."

RESULTS

After a detailed screening analysis and the application of specific selection criteria, we included in our review a total of 106 for qualitative synthesis. The studies were classified into various subparagraphs according to platelet characteristics analyzed: serotonergic system (5-HT2A receptors, SERT activity, and 5-HT content), adrenergic system, MAO activity, biomarkers of activation, responsivity, morphological changes, and other molecular pathways.

CONCLUSIONS

Despite the large amount of the literature examined, nonunivocal and, occasionally, conflicting results emerged. However, the findings on structural and metabolic alterations, modifications in the expression of specific proteins, changes in the aggregability, or in the responsivity to different pro-activating stimuli, may be suggestive of potential platelet dysfunctions in depressed subjects, which would result in a kind of hyperreactive state. This condition could potentially lead to an increased cardiovascular risk. In line with this hypothesis, we speculated that antidepressant treatments would seem to reduce this hyperreactivity while representing a potential tool for reducing cardiovascular risk in depressed patients and, maybe, in other neuropsychiatric conditions. However, the problem of the specificity of platelet biomarkers is still at issue and would deserve to be deepened in future studies.

Pharmacotherapeutic Strategies and New Targets in OCD

Effective pharmacological and psychotherapeutic treatments are well established for obsessive-compulsive disorder (OCD). Serotonin reuptake inhibitors (SRIs) are first-line treatment and are of benefit to about half of patients. Augmentation of SRI treatment with low-dose neuroleptics is an evidence-based second-line strategy. Specialty psychotherapy is also used as both first-line and second-line treatment and can benefit many. However, a substantial number of patients do not respond to these treatments. New alternatives are urgently needed. This review summarizes evidence for these established pharmacotherapeutic strategies, and for others that have been investigated in refractory disease but are not supported by the same level of evidence. We focus on three neurotransmitter systems in the brain: serotonin, dopamine, and glutamate. We summarize evidence from genetic, neuroimaging, animal model, and other lines of investigation that probe these three systems in patients with OCD. We also review recent work on predictors of response to current treatments. While many studies suggest abnormalities that may provide insight into the pathophysiology of the disorder, most studies have been small, and non-replication of reported findings has been common. Nevertheless, the gradual accrual of evidence for neurotransmitter dysregulation may in time lead the way to new pharmacological strategies.

OCD is associated with an altered association between sensorimotor gating and cortical and subcortical 5-HT1b receptor binding

Obsessive-compulsive disorder (OCD) is characterized by impaired sensorimotor gating, as measured using prepulse inhibition (PPI). This effect may be related to abnormalities in the serotonin (5-HT) system. 5-HT1B agonists can impair PPI, produce OCD-like behaviors in animals, and exacerbate OCD symptoms in humans. We measured 5-HT1B receptor availability using (11)C-P943 positron emission tomography (PET) in unmedicated, non-depressed OCD patients (n=12) and matched healthy controls (HC; n=12). Usable PPI data were obtained from 20 of these subjects (10 from each group). There were no significant main effects of OCD diagnosis on 5-HT1B receptor availability ((11)C-P943 BPND); however, the relationship between PPI and (11)C-P943 BPND differed dramatically and significantly between groups. 5-HT1B receptor availability in the basal ganglia and thalamus correlated positively with PPI in controls; these correlations were lost or even reversed in the OCD group. In cortical regions there were no significant correlations with PPI in controls, but widespread positive correlations in OCD patients. Positive correlations between 5-HT1B receptor availability and PPI were consistent across diagnostic groups only in two structures, the orbitofrontal cortex and the amygdala. Differential associations of 5-HT1B receptor availability with PPI in patients suggest functionally important alterations in the serotonergic regulation of cortical/subcortical balance in OCD.

Platelet serotonergic markers as endophenotypes for obsessive-compulsive disorder

Although compelling evidence has shown that obsessive-compulsive disorder (OCD) has a strong genetic component, its genetic basis remains to be elucidated. Identifying biological abnormalities in nonaffected relatives is one of the strategies advocated to isolate genetic vulnerability factors in complex disorders. Since peripheral serotonergic disturbances are frequently observed in OCD patients, the aim of this study was to investigate if they could represent endophenotypes, by searching for similar abnormalities in the unaffected parents of OCD patients. We assessed whole blood serotonin (5-HT) concentration, platelet 5-HT transporter (5-HTT) and 5-HT2A receptor-binding characteristics, and platelet inositol trisphosphate (IP3) content in a sample of OCD probands (n = 48) and their unaffected parents (n = 65), and compared them with sex- and age-matched controls (n = 113). Lower whole blood 5-HT concentration, fewer platelet 5-HTT-binding sites, and higher platelet IP3 content were found in OCD probands and their unaffected parents compared to controls. Whole blood 5-HT concentration showed a strong correlation within families (p < 0.001). The only parameter that appeared to discriminate affected and unaffected subjects was 5-HT2A receptor-binding characteristics, with increased receptor number and affinity in parents and no change in OCD probands. The presence of peripheral serotonergic abnormalities in OCD patients and their unaffected parents supports a familial origin of these disturbances. These alterations may serve as endophenotypic markers in OCD, and could contribute to the study of the biological mechanisms and genetic underpinnings of the disorder.

Platelet serotonergic predictors of clinical improvement in obsessive compulsive disorder

OBJECTIVE

Serotonin reuptake inhibitors (SRIs) are the most efficient pharmacological treatment of obsessive-compulsive disorders (OCD). Previous studies have suggested that some peripheral serotonergic parameters can be used to predict the clinical outcome of the treatment of OCD patients with SRIs. We tried to identify further peripheral serotonergic parameters that could help predict the clinical outcome of SRI treatment in a sample of patients with OCD.

METHODS

We compared 19 OCD patients before and after 8 weeks of SRI treatment with 19 sex-matched and age-matched controls. We assessed clinical improvement and whole-blood serotonin (5-HT) concentration, platelet 5-HT transporter (5-HTT) and 5-HT2A receptor binding characteristics and platelet IP3 content.

RESULTS

Before treatment, OCD patients had higher platelet IP3 content and fewer 5-HTT binding sites than the controls. Treatment with SRIs further lowered the number of 5-HTT binding sites, normalized platelet IP3 contents, and lowered the number of platelet 5-HT2A binding sites and whole-blood 5-HT concentrations below control values. The patients who improved most following SRI treatment had higher whole-blood 5-HT concentrations before treatment.

CONCLUSION

Our results confirm that whole-blood 5-HT concentration is a predictor for clinical improvement and indicate that abnormal intracellular mechanisms may be involved in OCD patients, in particular, the overstimulation of the phosphoinositide signaling system.

WCA recommendations for the long-term treatment of obsessive-compulsive disorder in adults

What are the latest psychotherapeutic and pharmacotherapeutic treatment recommendations for obsessive-compulsive disorder (OCD)? OCD is a relatively common disorder with a lifetime prevalence of approximately 2% in the general population. It often has an early onset, usually in childhood or adolescence, and frequently becomes chronic and disabling if left untreated. High associated healthcare utilization and costs, and reduced productivity resulting in loss of earning, pose a huge economic burden to OCD patients and their families, employers, and society. OCD is characterized by the presence of obsessions and compulsions that are time-consuming, cause marked distress, or significantly interfere with a person's functioning. Most patients with OCD experience symptoms throughout their lives and benefit from long-term treatment. Both psychotherapy and pharmacotherapy are recommended, either alone or in combination, for the treatment of OCD. Cognitive-behavioral therapy is the psychotherapy of choice. Pharmacologic treatment options include the tricyclic antidepressant clomipramine and the selective serotonin reuptake inhibitors (SSRIs) citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline. These have all shown benefit in acute treatment trials; clomipramine, fluvoxamine, fluoxetine, and sertraline have also demonstrated benefit in long-term treatment trials (at least 24 weeks), and clomipramine, sertraline, and fluvoxamine have United States Food and Drug Administration approvals for use in children and adolescents. Available treatment guidelines recommend first-line use of an SSRI (ie, fluoxetine, fluvoxamine, paroxetine, sertraline, or citalopram) in preference to clomipramine, due to the latter's less favorable adverse-event profile. Further, pharmacotherapy for a minimum of 1-2 years is recommended before very gradual withdrawal may be considered.

Decreased inhibitory activity of PKC in OCD patients after six months of treatment

We investigated 5-HT reuptake and protein kinase of type C (PKC) activation in platelets of 14 OCD patients at baseline and after six months of treatment with different serotonin (5-HT) reuptake inhibitors (SRIs). The results showed that all SRIs provoked a significant increase in both the maximal velocity (V(max)) and the Michaelis-Menten constant (K(m)) of 5-HT reuptake, as compared with baseline values. The activation of PKC by means of 4-beta-12-tetradecanoylphorbol 13-acetate provoked a significant decrease in V(max) values, but the effect was not as evident as at baseline. These findings could indicate that, in OCD patients, SRIs increase the rate of reuptake and decrease the inhibitory effect of PKC and that the two phenomena may be linked, the first perhaps depending upon the second.

Psychopathology and personality characteristics in relation to blood serotonin in Tourette's syndrome and obsessive-compulsive disorder

Family studies suggest an interrelationship between Gilles de la Tourette Syndrome (GTS) and some forms of obsessive-compulsive disorder (OCD). Some authors consider GTS to be part of a serotonergically mediated cluster of OCD spectrum disorders. The present study was undertaken to compare measures of psychopathology, personality and blood serotonin between GTS and OCD (without tics), and to investigate whether an OCD spectrum hypothesis is supported for GTS. Fifteen GTS without OCD subjects, 21 tic with (+) OCD subjects, 15 OCD without tic subjects and 26 controls (all without serotonergic medication) were evaluated with self-rated and clinician-rated measures of psychopathology and personality. Whole blood serotonin (5-HT) and platelet monoamine oxidase activity (MAO) was measured, and Spearman's correlations were calculated between whole blood 5-HT, MAO and rating scale scores within the entire sample and within subgroups. There were main effects of OCD on anxiety, obsessive-compulsive, neuroticism and extraversion scores. There were main effects of tics on depression, obsessive-compulsive, trait anxiety and neuroticism scores, and on platelet MAO. There were interaction effects on platelet MAO, 5-HT, Yale-Brown Obsessive-Compulsive Rating Scale severity, trait anxiety and Eysenck Personality Questionnaire neuroticism scores. Platelet MAO activity was elevated in tic-free OCD subjects when compared to tic + OCD, GTS without OCD and controls. Whole blood 5-HT was lowered in tic + OCD patients in comparison to GTS without OCD and tic-free OCD subjects. Whole blood 5-HT and obsessive-compulsive severity were negatively correlated within OCD without tic patients and MAO and Leyton Obsessive Inventory scores were negatively related within GTS without OCD patients. The biochemical data of this study suggest that in tic + OCD and in tic-free OCD patients, 5-HT dysregulations play a role, but not necessarily in pure GTS. Serotonergic dysregulations within tic + OCD and tic-free OCD patients are distinct, suggesting differences in underlying pathophysiology. The finding that obsessions and compulsions can be associated with either 5-HT hypofunctionality or hyperfunctionality reveals a major weakness in the OCD spectrum theory, i.e. that the associations between obsessive-compulsive behaviours and 5-HT abnormalities are less specific than suggested by the original obsessive-compulsive spectrum model.

Pharmacological treatment of childhood obsessive-compulsive disorder: from theory to practice

Discusses pharmacological treatment of childhood obsessive-compulsive disorder (OCD), chronic and underrecognized psychiatric condition that affects up to 2% to 3% of children and adolescents. Research in OCD in children, including neuropharmacology, brain imaging, genetics, and clinical phenomenology, informs current views of OCD pathophysiology. Contemporary research supports the notion of a dysregulation in serotonin subsystems in the central nervous system, with target areas of dysfunction including basal ganglia and orbitofrontal cortex. Pharmacotherapy, along with cognitive-behavioral approaches, constitutes the indicated treatment for childhood OCD. Pharmacological treatment is best guided by a phenomenological understanding of the type of obsessions and compulsions, the intensity and frequency of their presentation with attention to behavioral reinforcements, and psychosocial factors that affect the course of the disease. Serotonin-enhancing agents, such as fluoxetine, fluvoxamine, paroxetine, and sertraline and citalopram (SSRIs) are first-line pharmacological agents, whereas refractory symptoms can be treated by augmentation with neuroleptics or other agents. Clomipramine is as effective as the SSRIs but its use may be accompanied by increased side effects. Genetic factors probably influence susceptibility to OCD as well as response to treatment, and the elucidation of these and other risk factors will be important elements in the future understanding and treatment of this disorder.

Decreased platelet 3H-paroxetine binding in untreated panic disorder patients

Different findings support the involvement of the serotonin (5-HT) system in panic disorder. The presence of the 5-HT transporter in blood platelets similar to that in presynaptic serotonergic neurons, permits the investigation of this structure in periphery. We therefore evaluated the binding of 3H-paroxetine, a selective 5-HT reuptake inhibitor which is considered the ligand of choice for labelling the 5-HT transporter, in platelets of 20 drug-free patients with panic disorder. The same measurement was repeated after one year's treatment with different drugs. The results showed patients to have a lower number of 3H-paroxetine sites than a group of age- and sex-matched controls, thus suggesting the involvement of the 5-HT transporter in panic disorder. This abnormality reverted after one year of treatment with specific drugs that provoked the symptom remission in all cases, which would suggest a link with the clinical improvement.

Self-help and guided self-help treatments for bulimia nervosa and binge eating disorder

This article reviews the use of self-help and guided self-help treatments for bulimia nervosa (BN) and binge eating disorder (BED). Available data suggest that self-help and guided self-help treatments based on empirically-supported cognitive behavioral therapies (CBT) have efficacy for binge eating problems. Emerging findings from initial studies suggest that the magnitude of the differences in outcomes between certain guided-self-help CBT programs and therapist-led CBT may not be substantial, although further research is clearly indicated. Initial data suggest that self-help and guided self-help CBT programs may not only demonstrate "efficacy" but also "effectiveness"-i.e., utility in "real-world" primary care or community settings. Implications for clinical practice and for future research are discussed.