Gender moderates the relationship between mania spectrum and serotonin transporter polymorphisms in depression

Effects of serotonin transporter and receptor polymorphisms on depression

INTRODUCTION

Serotonin is highly implicated in the regulation of emotional state and the execution of cognitive tasks, so much so that the serotonin transporter genes (5-HTT, SLC6A4) and the serotonin receptor genes (HTR1A, HTR1B, HTR2A) have become the perfect candidates when studying the effects that these genes and their polymorphic variations have on depression characteristics.

OBJECTIVE

A review of research reports that have studied the effects of variations in the serotonin transporter and receptor genes on different clinical features of depression.

METHODS

A search of the Scopus, Web of Science and PubMed databases was conducted using the keywords ("depression" AND "polymorphism").

CONCLUSIONS

According to the review of 54 articles, the short allele of the 5-HTTLPR polymorphism was found to be the most reported risk factor related to the development of depression and its severity. Variations in the genes studied (SLC6A4, HTR1A, HTR2A) can generate morphological alterations of brain structures.

Effects of Serotonin Transporter and Receptor Polymorphisms on Depression

INTRODUCTION

Serotonin is highly implicated in the regulation of emotional state and the execution of cognitive tasks, so much so that the serotonin transporter genes (5-HTT, SLC6A4) and the serotonin receptor genes (HTR1A, HTR1B, HTR2A) have become the perfect candidates when studying the effects that these genes and their polymorphic variations have on depression characteristics.

OBJECTIVE

A review of research reports that have studied the effects of variations in the serotonin transporter and receptor genes on different clinical features of depression.

METHODS

A search of the Scopus, Web of Science and PubMed databases was conducted using the keywords ("depression" AND "polymorphism").

CONCLUSIONS

According to the review of 54 articles, the short allele of the 5-HTTLPR polymorphism was found to be the most reported risk factor related to the development of depression and its severity. Variations in the genes studied (SLC6A4, HTR1A, HTR2A) can generate morphological alterations of brain structures.

Can sleep disturbance be a cue of mood spectrum comorbidity? A preliminary study in panic disorder

OBJECTIVE

To investigate if sleep disturbances may affect treatment outcomes of patients with panic disorder (PD).

METHODS

Eighty-five PD outpatients with no Axis I comorbidity for mood disorders completed a baseline assessment (T1) and were evaluated after 3 (T2), 6 (T3) and 12 months (T4), with the Panic Disorder Severity Scale (PDSS) total score as outcome measure during a 12-month naturalistic follow-up. Patients were assessed with the Mood Spectrum Self-Report (MOODS-SR, Lifetime Version), and the PDSS.

RESULTS

Forty-three patients (50.5%) met criteria for remission (PDSS<5) and 42 (49.5%) for no remission. In a logistic regression model with remission as the dependent variable, MOODS-SR sleep disturbances was the only determinant for a lower likelihood of PD remission. The items accounting for this result were the following: Repeated difficulty falling asleep (chi-square = 4.4; df = 1; p = 0.036), and Repeatedly waking up in the middle of the night (chi-square = 5.2; df = 1; p = 0.022).

CONCLUSION

Lifetime sleep disturbances would represent a cue of mood spectrum (in absence of overt affective comorbidity) that may impair remission in PD.

The Impact of Gender on Interferon-Associated Depression and Anxiety

Population studies indicate women have higher prevalences of depression and anxiety than men. Interferon (IFN) is a biologic agent that can induce or exacerbate depression and/or anxiety. Whether women are more likely to experience these side effects of IFN during treatment remains to be determined. The aim of this study was to document levels of depression and anxiety in female and male patients before and during IFN-based treatment. This was a prospective open-label study in which depression was measured by Beck Depression Inventory (BDI) and anxiety by Hospital Anxiety and Depression Scale (HADS). Before treatment, the prevalence of depression was higher in females (3/13 [23%]) than males (1/25 [4%]), but the difference did not reach statistical significance (P = 0.12). Initial BDI scores were also higher in females but not significantly (P = 0.07). During treatment, BDI scores increased to a similar extent in both genders. A similar percentage of nondepressed patients at baseline developed depression (females: 50% versus males: 35%, P = 0.45). Before treatment, anxiety was significantly more common in females (7/13 [54%]) than males (3/25 [12%]) (P = 0.016) and median HADS scores were higher in females (P = 0.03). During treatment, increases in HADS scores were similar in the 2 genders. A similar percentage of patients without anxiety at baseline developed anxiety on treatment (females: 50% versus males: 23%, P = 0.31). The frequency and extent of IFN-induced/exacerbated depression and anxiety are not gender dependent.

Sex differences modulating serotonergic polymorphisms implicated in the mechanistic pathways of risk for depression and related disorders

Despite consistent observations of sex differences in depression and related emotional disorders, we do not yet know how these sex differences modulate the effects of genetic polymorphisms implicated in risk for these disorders. This Mini-Review focuses on genetic polymorphisms of the serotonergic system to illustrate how sex differences might modulate the neurobiological pathways involved in the development of depression. We consider the interacting role of environmental factors such as early-life stress. Given limited current knowledge about this topic, we highlight methodological considerations, challenges, and guidelines for future research. © 2016 Wiley Periodicals, Inc.

5-HTTLPR and gender differences in affective disorders: A systematic review

BACKGROUND

Serotonin transporter-linked polymorphic region (5-HTTLPR) variants have been extensively studied in psychiatric disorders. Although gender effects have been reported, they have not been comprehensively reviewed. The aim of our study was to summarize literature findings on 5-HTTLPR and gender differences in affective disorders.

METHODS

A systematic search of PubMed, ISI Web of Knowledge, and PsycINFO databases was performed for dates until January 2015. The included articles (n=78) analyzed the association between 5-HTTLPR and affective spectrum disorders, taking into account gender. The quality of each study was assessed through STROBE and CONSORT.

RESULTS

5-HTTLPR modulation of affective disorders varied by gender. The S allele (or SS genotype) seemed to be differently associated with an increased risk of depression, depressive symptoms, anxiety traits and symptoms, and symptoms of internalizing behavior among women and an increased risk of aggressiveness, conduct disorder and symptom counts of externalizing behavior among men. Moreover, the presence of stressful life events reinforced the association. Interestingly, these differences seemed to begin with adolescence and were not consistent among the elderly, suggesting a plausible role of hormonal fluctuations.

LIMITATIONS

The review is limited by the small number of included papers, due to the paucity of information in the literature regarding 5-HTTLPR and gender.

CONCLUSIONS

5-HTTLPR variants may exert a differential modulation on a number of features depending on gender. Further studies are needed to more deeply investigate the effect of 5-HTTLPR×gender on the modulation of affective disorders.

Mood Spectrum Model: Evidence reconsidered in the light of DSM-5

AIM: to investigate studies conducted with the Mood Spectrum Structured Interviews and Self-Report versions (SCI-MOODS and MOODS-SR).

METHODS: We conducted a review of studies published between 1997 and August 2014. The search was performed using Pubmed and PsycINFO databases. Analysis of the papers followed the inclusion and exclusion criteria recommended by the PRISMA Guidelines, namely: (1) articles that presented a combination of at least two terms, “SCI-MOODS” [all fields] or “MOODS-SR” [all fields] or “mood spectrum” [all fields]; (2) manuscript in English; (3) original articles; and (4) prospective or retrospective original studies (analytical or descriptive), experimental or quasi-experimental studies. Exclusion criteria were: (1) other study designs (case reports, case series, and reviews); (2) non-original studies including editorials, book reviews and letters to the editor; and (3) studies not specifically designed and focused on SCI-MOODS or MOODS-SR.

RESULTS: The search retrieved 43 papers, including 5 reviews of literature or methodological papers, and 1 case report. After analyzing their titles and abstracts, according to the eligibility criteria, 6 were excluded and 37 were chosen and included. The SCI-MOODS and the MOODS-SR have been tested in published studies involving 52 different samples across 4 countries (Italy, United States, Spain and Japan). The proposed mood spectrum approach has demonstrated its usefulness mainly in 3 different areas: (1) Patients with the so-called “pure” unipolar depression that might manifest hypomanic atypical and/or sub-threshold aspects systematically detectable with the mood questionnaire; (2) Spectrum features not detected by other instruments are clinically relevant, because they might manifest in waves during the lifespan, sometimes together, sometimes alone, sometimes reaching the severity for a full-blown disorder, sometimes interfering with other mental disorders or complicating the course of somatic diseases; and (3) Higher scores on the MOODS-SR factors assessing “psychomotor disturbances”, “mixed instability” and “suicidality” delineate subtypes of patients characterized by the more severe forms of mood disorders, the higher risk for psychotic symptoms, and the lower quality of life after the remission of the full-blown-episode.

CONCLUSION: The mood spectrum model help researchers and clinicians in the systematic assessment of those areas of psychopathology that are still neglected by the Diagnostic and Statistical Manual of Mental Disorders 5 classification.

Gender-specific association between the COMT Val158Met polymorphism and openness to experience in panic disorder patients

BACKGROUND

Because major depression and panic disorder are both more prevalent among females and since several lines of evidence suggest that genetic factors might influence an individual's vulnerability to panic disorder, gene-gender interactions are being examined in such psychiatric disorders and mental traits. A number of studies have suggested that specific genes, e.g. catechol-O-methyltransferase (COMT), might lead to distinct clinical characteristics of panic disorder.

METHOD

We compared gender-specific personality-related psychological factors of 470 individuals with panic disorder and 458 healthy controls in terms of their COMT Val158Met polymorphism and their scores on the Revised NEO Personality Inventory (NEO PI-R) and State-Trait Anxiety Inventory (STAI) with a 1-way analysis of covariance.

RESULTS

In the male panic disorder patients, the NEO PI-R score for openness to experience was significantly lower in the Met/Met carrier group, whereas there was no such association among the female panic disorder patients or the male or female control groups.

CONCLUSION

The gender-specific effect of the COMT genotype suggests that the COMT Val/Met genotype may influence a personality trait, openness to experience, in males with panic disorder.

Baseline Comorbidities Enhance the Risk of Treatment-Induced Depression in HCV-Infected Men: A Pilot Study

BACKGROUND

Hepatitis C virus (HCV) infection is associated with clinical depression,a condition that is aggravated on interferon-based therapy. In HCV infection, men often appear more resilient to depression than women. However, men are subject to depression in diseases that tend to be comorbid in HCV-infected.

AIM

This study examined whether HCV-infected men with baseline comorbidities were more or less susceptible to depression prior to and on treatment.

METHODS

Patients with chronic HCV infection preparing to begin treatment participated (n = 37). The presence of baseline comorbidities was determined by pretreatment medication regimes. Depression was measured by the Beck Depression Inventory prior to and following 2, 4, 8, and 12 weeks of interferon therapy.

RESULTS

At baseline, cohorts with (n = 16) and without (n = 21) comorbidities had equivocal demographics and infection characteristics. Comorbidities did not associate with baseline depression. However, on treatment, men with baseline comorbidities demonstrated an elevated risk for the onset of de novo depression (odds ratio = 19.25; confidence interval = 1.41, 582.14; p = .008). This was not observed for women. Baseline comorbidities did not alter the need for treatment discontinuations or the ability to achieve a sustained viral response.

CONCLUSION

The results of this study suggest that baseline comorbidities render men more susceptible to interferon treatment-induced depression.

Paternal age effect on age of onset in bipolar I disorder is mediated by sex and family history

This study investigated for the first time in the psychiatric literature the effect of parental age on age-of-onset (AO) in bipolar I disorder (BPI) in relation to proband sex and family history (FH) for major psychoses in a sample of 564 BPI probands. All probands, 72.68% of their first-degree and 12.13% of their second-degree relatives were directly interviewed. The FH-method was used for all unavailable relatives. The diagnoses were made according to DSM-IV(TR) . The impact of parental age on proband early/late AO was evaluated through logistic regression with the cut-off for early AO determined through commingling analysis. We found evidence for a significant influence of increasing paternal age, and especially age ≥ 35 years, on AO of BPI disorder in the total sample (OR = 0.54, CI: 0.35-0.80), in the female subsample (OR = 0.44, CI: 0.25-0.78), in the sporadic subsample (OR = 0.64, CI: 0.38-0.95), and in the subsample with FH of recurrent unipolar major depression (Mdd-RUP) (OR = 0.55, CI: 0.34-0.87). No significant effect of paternal age on disease AO was found in patients with FH of bipolar (BP), schizoaffective disorders (SA), or schizophrenia (SCZ), nor in males. Mean age was significantly higher in fathers of sporadic cases and of cases with FH of Mdd-RUP than in fathers of cases with FH of BP/SA/SCZ (P = 0.011). Maternal age had no significant effect either in the total sample or in subsamples defined by proband sex or FH. In conclusion, in our sample increasing paternal age lowered the onset of BPI selectively, the effect being related to the female sex and FH-type.

Perception of thermal pain and the thermal grill illusion is associated with polymorphisms in the serotonin transporter gene

Aim

The main aim of this study was to assess if the perception of thermal pain thresholds is associated with genetically inferred levels of expression of the 5-HT transporter (5-HTT). Additionally, the perception of the so-called thermal grill illusion (TGI) was assessed. Forty-four healthy individuals (27 females, 17 males) were selected a-priori based on their 5-HTTLPR/rs25531 (‘tri-allelic 5-HTTLPR’) genotype, with inferred high or low 5-HTT expression. Thresholds for heat- and cold-pain were determined along with the sensory and affective dimensions of the TGI.

Results

Thresholds to heat- and cold-pain correlated strongly (rho  = −0.58, p<0.001). Individuals in the low 5-HTT-expressing group were significantly less sensitive to heat-pain (p = 0.02) and cold-pain (p = 0.03), compared to the high-expressing group. A significant gender-by-genotype interaction also emerged for cold-pain perception (p = 0.02); low 5-HTT-expressing females were less sensitive. The TGI was rated as significantly more unpleasant (affective-motivational dimension) than painful (sensory-discriminatory dimension), (p<0.001). Females in the low 5-HTT expressing group rated the TGI as significantly less unpleasant than high 5-HTT expressing females (p<0.05), with no such differences among men.

Conclusion/Significance

We demonstrate an association between inferred low 5-HTT expression and elevated thresholds to thermal pain in healthy non-depressed individuals. Despite the fact that reduced 5-HTT expression is a risk factor for chronic pain we found it to be related to hypoalgesia for threshold thermal pain. Low 5-HTT expression is, however, also a risk factor for depression where thermal insensitivity is often seen. Our results may thus contribute to a better understanding of the molecular underpinnings of such paradoxical hypoalgesia. The results point to a differential regulation of thermoafferent-information along the neuraxis on the basis of 5-HTT expression and gender. The TGI, suggested to rely on the central integration of thermoafferent-information, may prove a valuable tool in probing the affective-motivational dimension of these putative mechanisms.

Genome-wide association studies in ADHD

Attention-deficit/hyperactivity disorder, ADHD, is a common and highly heritable neuropsychiatric disorder that is seen in children and adults. Although heritability is estimated at around 76%, it has been hard to find genes underlying the disorder. ADHD is a multifactorial disorder, in which many genes, all with a small effect, are thought to cause the disorder in the presence of unfavorable environmental conditions. Whole genome linkage analyses have not yet lead to the identification of genes for ADHD, and results of candidate gene-based association studies have been able to explain only a tiny part of the genetic contribution to disease, either. A novel way of performing hypothesis-free analysis of the genome suitable for the identification of disease risk genes of considerably smaller effect is the genome-wide association study (GWAS). So far, five GWAS have been performed on the diagnosis of ADHD and related phenotypes. Four of these are based on a sample set of 958 parent-child trio's collected as part of the International Multicentre ADHD Genetics (IMAGE) study and genotyped with funds from the Genetic Association Information Network (GAIN). The other is a pooled GWAS including adult patients with ADHD and controls. None of the papers reports any associations that are formally genome-wide significant after correction for multiple testing. There is also very limited overlap between studies, apart from an association with CDH13, which is reported in three of the studies. Little evidence supports an important role for the 'classic' ADHD genes, with possible exceptions for SLC9A9, NOS1 and CNR1. There is extensive overlap with findings from other psychiatric disorders. Though not genome-wide significant, findings from the individual studies converge to paint an interesting picture: whereas little evidence-as yet-points to a direct involvement of neurotransmitters (at least the classic dopaminergic, noradrenergic and serotonergic pathways) or regulators of neurotransmission, some suggestions are found for involvement of 'new' neurotransmission and cell-cell communication systems. A potential involvement of potassium channel subunits and regulators warrants further investigation. More basic processes also seem involved in ADHD, like cell division, adhesion (especially via cadherin and integrin systems), neuronal migration, and neuronal plasticity, as well as related transcription, cell polarity and extracellular matrix regulation, and cytoskeletal remodeling processes. In conclusion, the GWAS performed so far in ADHD, though far from conclusive, provide a first glimpse at genes for the disorder. Many more (much larger studies) will be needed. For this, collaboration between researchers as well as standardized protocols for phenotyping and DNA-collection will become increasingly important.