Aberrant Brain Signal Variability and COMT Genotype in Chronic TMD Patients.

The analysis of brain signal variability is a promising approach to understand pathological brain function related to chronic pain. This study investigates whether blood-oxygen-level-dependent signal variability (BOLDSV) in specific frequency bands is altered in temporomandibular disorder (TMD) and correlated to its clinical features. Twelve patients with chronic myofascial TMD and 24 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging. The BOLDSV was measured as the standard deviation of the BOLD time series at each voxel and compared between groups. We also examined the potential relationship between the BOLDSV and the catechol-O-methyltransferase (COMT) Val158Met polymorphism. We assessed sensory-discriminative pain in the craniofacial region, pain sensitivity to sustained masseteric pain challenge, and TMD pain frequency for clinical correlation. Patients displayed reduced BOLDSV in the dorsolateral prefrontal cortex (dlPFC) as compared with HC in all frequency bands. In the slow-3 band, patients also showed reduced BOLDSV in the medial dorsal thalamus, primary motor cortex (M1), and primary somatosensory cortex (S1) and heightened BOLDSV in the temporal pole. Notably, we found a significant correlation between lower BOLDSV (slow-3) in the orofacial M1/S1 regions and higher clinical pain (intensity/area) and higher sensitivity of the masseter muscle pain. Moreover, lower BOLDSV (slow-3) in the dlPFC and ventrolateral PFC was associated with a higher TMD pain frequency. Participants who had the COMT158Met substitution exhibited lower BOLDSV in the dlPFC and higher BOLDSV in the temporal pole as compared with participants without the COMT158Met substitution. An increasing number of Met alleles was associated with lower dlPFC and greater temporal pole BOLDSV in both HC and TMD groups. Together, we demonstrated that chronic TMD patients exhibit aberrant BOLDSV in the top-down pain modulatory and sensorimotor circuits associated with their pain frequency and severity. COMT Val158Met polymorphism might affect clinical symptoms in association with regional brain signal variability, specifically involved in cognitive and emotional regulation of pain.

Clinical Pharmacogenetics Implementation Consortium guideline for CYP2D6 and CYP2C19 genotypes and dosing of tricyclic antidepressants.

Polymorphisms in CYP2D6 and CYP2C19 affect the efficacy and safety of tricyclics, with some drugs being affected by CYP2D6 only, and others by both polymorphic enzymes. Amitriptyline, clomipramine, doxepin, imipramine, and trimipramine are demethylated by CYP2C19 to pharmacologically active metabolites. These drugs and their metabolites, along with desipramine and nortriptyline, undergo hydroxylation by CYP2D6 to less active metabolites. Evidence from published literature is presented for CYP2D6 and CYP2C19 genotype-directed dosing of tricyclic antidepressants.

The influence of metabolic syndrome, physical activity and genotype on catechol-O-methyl transferase promoter-region methylation in schizophrenia.

The catechol-O-methyl transferase (COMT) 158Val/Met variant has been suggested to play a role in COMT function. Epigenetic regulation of COMT may further influence the prevalence of metabolic syndrome in these patient populations. This study examined the correlation between COMT promoter methylation and metabolic syndrome in schizophrenia patients receiving atypical antipsychotic (AAP) therapy. DNA was extracted from peripheral blood samples of schizophrenia subjects screened for metabolic syndrome. Pyrosequencing was used to analyze two methylation sites of the soluble COMT (COMT-s) promoter region. Associations between AAP use, lifestyle variables, metabolic syndrome and COMT genotype with peak methylation values were analyzed. Data are reported in 85 subjects. Methylation on CpG site 1 had a mean of 79.08% (±4.71) and it was 12.43% (±1.19) on site 2. COMT genotype proved to be an indicator of COMT methylation status on site 1 (F(2, 84)=5.78, P=0.0044) and site 2 (F(2, 84),=3.79, P=0.027). A significant negative correlation between physical activity and COMT promoter region methylation was found in Val/Val homozygous patients (site 1: P=0.013 and site 2: P=0.019). Those homozygous for Met/Met showed a positive correlation between promoter site methylation and physical activity (site 1: P=0.027, site 2: P=0.005), and between CpG site methylation and metabolic syndrome (site 1: P=0.002; site 2: P=0.001). The results of this study suggest that COMT promoter region methylation is largely influenced by COMT genotype and that physical activity plays a significant role in epigenetic modulation of COMT.

The influence of the brain-derived neurotropic factor Val66Met genotype and HMG-CoA reductase inhibitors on insulin resistance in the schizophrenia and bipolar populations.

INTRODUCTION: The brain-derived neurotrophic factor (BDNF) Val66Met variant and HMG-COA reductase inhibitors (statins) have been implicated in insulin resistance with a possible increased risk of diabetes. We sought to determine the effect of the BDNF Met variant and statin medication use on insulin resistance in schizophrenia and bipolar disorder using the homeostasis model assessment of insulin resistance (HOMA-IR). METHODS: A cross-sectional design was used and patients with diabetes or on any medications affecting glucose regulation were -excluded. Associations between insulin resistance and genotype were then analyzed by ANOVA and regression analysis. Subjects were grouped by BDNF genotype as well as presence of statin. RESULTS: Two hundred fifty-two subjects with a mean age of 44 years were included. The group was 53% male and 41% had a diagnosis of bipolar disorder; 78% and 19% were receiving atypical antipsychotics (AAPs) and statin medications, respectively. Analysis showed schizophrenia subjects with the BDNF met allele as well as schizophrenia subjects with both the BDNF met allele and were receiving a statin had significantly higher HOMA-IR values compared to the other groups (p= 0.046 and p= 0.016, respectively). CONCLUSIONS: Our results suggest that in the metabolically high-risk population of schizophrenia the BDNF met allele alone and in combination with statin medications is associated with higher insulin resistance values. This was not seen in the bipolar population. Further validation of these associations remains necessary.

Association between cytochrome P4502D6 (CYP2D6) genotype, antipsychotic exposure, and abnormal involuntary movement scale (AIMS) score.

Antipsychotic metabolism cosegregates with the polymorphic cytochrome P4502D6 (CYP2D6) hepatic enzyme. Approximately 5-10% of Caucasians show impaired metabolism associated with nonfunctional alleles. Genotyping determines the number of functional alleles, which is phenotypically not possible. The aim of this study was to investigate associations between CYP2D6 genotype, antipsychotic exposure, and abnormal involuntary movement scale (AIMS) score. Schizophrenic patients (DSM-IV) were genotyped for CYP2D6*1, *3, and *4 alleles by nested polymerase chain reaction. A complete history, including psychiatric symptoms, medications and AIMS score was obtained. Antipsychotic exposure was recorded in dose years [(chlorpromazine equivalents x years)/100]. A linear regression model used AIMS scores as the dependent variable. Genotype, gender, antipsychotic exposure, and interactions were independent variables. The results of the 31 patients studied showed: 20 were homozygous for the *1 allele (*1/*1) and 11 were heterozygous for the *1 allele (i.e. *1/*3 or *4). Age, sex, age of onset, treatment duration, antipsychotic exposure, and AIMS scores did not differ between groups. The interaction between dose years and genotype was significant (P < 0.0055), demonstrating that for (*1/*1) patients, the magnitude of antipsychotic exposure had a greater effect on AIMS score (slope = 0.044) compared with (*1/*3 or *4) patients (slope = 0.001). These results suggest patients with a *3 or *4 allele may have a higher risk for developing antipsychotic induced abnormal movements.

Pharmacogenetic screening for susceptibility to fetal malformations in women.

OBJECTIVE: To present a review of the literature and research on the pharmacogenetics of congenital defects, with a focus on the need for predictive maternal genotype assays. DATA SOURCE: MEDLINE searches (January 1985-January 1999), past reference reviews, and unpublished research. STUDY SELECTION: Review of relevant human, animal, and basic science studies. DATA EXTRACTION: Data on research on polymorphisms, genotyping, cytochrome P450 enzyme systems, epoxide hydrolase, folate metabolism, metabolism of anticonvulsant medications, molecular genetics of neural tube defects, variations in drug metabolism, and environmental exposures were evaluated. DATA SYNTHESIS: Data synthesis includes not only a review of the literature but suggests ways such data might be used to facilitate the development of maternal genotype assays, with the goal of preventing birth defects. CONCLUSIONS: Individuals vary in how they metabolize drugs and handle toxic environmental exposures. In an ideal pregnancy, there is no or limited exposure to medications and environmental agents. However, in women with chronic medical conditions such as heart disease and seizures, this is often not possible. Unfortunately, no techniques have been available to identify those at risk in this population. Gene polymorphisms for a specific enzyme may result in an absence or reduction in the level of enzyme activity or in no change at all, with little effect on the structure/function of the gene product(s); they are not associated with clinical phenotypes in either the mother or the fetus. Other polymorphisms may be only markers. Thus, developing genotyping assays for women that are predictive of phenotype expression in the fetus is the key to screening for polymorphisms. As more mutations are identified and clinical, pharmacologic, biologic, and pharmacokinetic relationships are established, using these polymorphisms to develop a genotyping assay for women may become a clinical reality, possibly leading to preventive prepregnancy or prenatal treatment that may play an increasingly effective role in maternal care.

Lack of menstrual cycle effects on hypothalamic-pituitary-adrenal axis response to insulin-induced hypoglycaemia.

OBJECTIVE: Limited data are available on the effects of the menstrual cycle on the hypothalamic-pituitary-adrenal axis (HPA) function. This study evaluates HPA axis reactivity to insulin-induced hypoglycaemia over the menstrual cycle. PATIENTS: Twelve normal women were randomized to placebo and evaluated during three successive menstrual cycles. Menstrual phase was documented by menstrual diary and by oestradiol and progesterone levels at the time of each insulin tolerance test (ITT). Six normal men were included as a comparison in the statistical analysis. MEASUREMENTS: Afternoon ITTs were performed initially on the second or third day of menses in women, then seven more ITTs followed at one or two week intervals during the next 10 weeks. Serum measurements of glucose, adrenocorticotrophin (ACTH) and cortisol were obtained. RESULTS: The glucose and ACTH responses to the ITTs were similar between men and women. Cortisol levels at baseline and during the test were higher in men than in women, although the amount of change was similar. Glucose, ACTH and cortisol response to insulin-induced hypoglycaemia did not vary over the menstrual cycle or during repeat testing in men or women. CONCLUSIONS: These data show that it is unnecessary to control for menstrual cycle during insulin tolerance tests performed at 1600 hours. It is, however, necessary to control for the effect of sex on cortisol levels. Repeat testing more than one week apart does not appear to influence the glucose, ACTH or cortisol response to insulin stress.

Pharmacotherapy of primary obsessive-compulsive disorder: review of the literature.

Obsessive-compulsive disorder (OCD) is a chronic illness that affects 2-3% of Americans during their lifetime. It is characterized by recurrent obtrusive thoughts (obsessions) that compel patients to perform repetitive behaviors that can be excessively time consuming and cause marked distress. More than 40 controlled trials have been published on the treatment of OCD. Of drugs available to treat the disorder, serotonin reuptake inhibitors (SRIs) are most studied. With SRIs, symptoms improve in 22-62% of patients, but complete remission is rare. An agent is often selected based on side effects and patient tolerance, since SRIs are all equally effective. If no response is seen with average dosages, dosages should be increased to the maximum within 4-8 weeks from starting treatment. In patients with partial response, the dosage should be increased to the maximum by 5-9 weeks. Before determining the effectiveness of therapy, a trial of 8-13 weeks is necessary.

Testosterone suppression of the HPT axis.

BACKGROUND: Although studies have demonstrated the suppression of normal gonadal function in the experimental setting, the specific mechanisms by which androgenic-anabolic steroids impact male gonadal function remain ill defined. Following 2 consecutive weekly injections of an identically appearing testosterone cypionate (TC) placebo, subjects were randomized to a TC dose of 100 mg/wk, 250 mg/wk, or 500 mg/wk. Following the last weekly injection of active agent the subjects received 12 consecutive weeks of TC placebo injections. RESULTS: Spermatogenesis was impaired by each of the doses of TC employed in this study, but the observed decreases in, sperm count were neither strictly dose dependent nor consistent between individuals treated with the same dose. Basal leuteinizing hormone (LH) and follicle stimulating hormone (FSH) became undetectable 2 weeks after the start of 250 and 500 mg/wk TC injections and were lost within 5 to 6 weeks of starting 100 mg doses. Pituitary gonadotropin responses to leutinizing hormone releasing hormone (LHRH) disappeared more slowly with FSH responses being lost 1 to 3 weeks after the loss of basal FSH activity. Leuteinizing hormone responses to LHRH appeared to be suppressed last, disappearing 4 to 6 weeks after FSH responses to LHRH. CONCLUSIONS: Exogenous testosterone-mediated inhibitory influences on the hypothalamic-pituitary-testicular axis were reversed following the cessation of drug treatment.

The effects of anabolic steroids on driving performance as assessed by the Iowa Driver Simulator.

The effect of physiologic (100 mg/wk) and supraphysiologic (250 and 500 mg/wk) doses of testosterone cypionate (TC) on automobile driving were studied using the Iowa Driver Simulator. Six normal subject volunteers were studied off TC and on TC once steady-state concentrations were achieved after at least three weeks of dosing. Despite the administration of supraphysiologic testosterone doses, an increase in aggressive driving behavior was not detected. Likewise, corresponding psychometric testing using the Buss-Durkee Hostility Inventory to assess aggression was unable to detect any change in aggression in the test subjects. Although aggressive driving behavior may be increased by testosterone administration, the drug itself may not be responsible for these effects. Supraphysiologic doses greater than 500 mg/wk and a semi-controlled research environment may be necessary to produce this effect since case reports of AAS abuse causing altered driving behavior may be multifactorial in nature.

Nefazodone: a new antidepressant.

The chemistry, pharmacology, pharmacokinetics, and clinical efficacy of nefazodone hydrochloride, a new antidepressant, are described. Nefazodone enhances serotonin (5-hydroxytryptamine [5-HT]) synaptic transmission by acting as an antagonist at 5-HT2 receptors and by inhibiting the reuptake of 5-HT. These two mechanisms combined may enhance 5-HT1A-mediated transmission. In addition, nefazodone weakly inhibits the reuptake of norepinephrine. Nefazodone is a structural analogue of trazodone but is pharmacologically distinct. In placebo-controlled trials, nefazodone was as effective as imipramine for the treatment of major depression and produced clinical benefits in patients with depression-related anxiety and sleep disturbances. More than 2000 patients have received nefazodone in clinical trials. The most commonly reported adverse drug reactions (ADRs) are asthenia, somnolence, dry mouth, nausea, constipation, dizziness, lightheadedness, confusion, abnormal vision, and blurred vision. The incidence of sexual-dysfunction ADRs may be less than that reported for other antidepressants. Nefazodone does not inhibit rapid-eye movement sleep. Nefazodone, an inhibitor of the hepatic P-450 isoenzyme CYP3A4, may increase concentrations of drugs metabolized by this isoenzyme, such as terfenadine, astemizole, triazolam, alprazolam, and midazolam. Caution should be exercised in administering nefazodone hydrochloride with triazolobenzodiazepines, and coadministration with terfenadine or astemizole is contra-indicated. The dosage should start at 100 mg twice daily and then be increased, depending on occurrence of ADRs and the patient's clinical response, to 300-600 mg daily. In elderly or debilitated patients, the initial dosage should be half the usual dosage. Nefazodone hydrochloride is as effective as other available antidepressants and may cause fewer ADRs.

Venlafaxine: a heterocyclic antidepressant.

The pharmacology, pharmacokinetics, and clinical efficacy of venlafaxine hydrochloride, a new antidepressant, are described. Venlafaxine inhibits the reuptake of serotonin, norepinephrine, and, to a lesser extent, dopamine. In animal models, it does not significantly inhibit muscarinic, histaminic, or adrenergic receptor activity and does not inhibit monoamine oxidase. Venlafaxine is rapidly absorbed and metabolized in the liver to its active metabolite, O-desmethylvenlafaxine (ODV). Time to peak concentration is one to two hours for the parent compound and four to five hours for ODV. The pharmacokinetics of venlafaxine might be dose-dependent, although pharmacokinetic studies have had conflicting results. The major route of elimination is renal; thus, patients with renal dysfunction may require lower doses. In double-blind, placebo-controlled trials of venlafaxine for maintenance therapy, venlafaxine has shown effective antidepressant activity in severely ill patients with major depression. Antidepressant effectiveness may be apparent within two weeks; this finding needs to be replicated. The dosage is 75-375 mg/day administered in two or three divided doses. The strength of the antidepressant response may be correlated with increasing dosage. Nausea is the most commonly reported adverse drug reaction (ADR). Others include somnolence, dizziness, dry mouth, and sweating. All ADRs have commonly occurred at the beginning of therapy and decreased with time. Overall, venlafaxine is well tolerated. Venlafaxine is as effective as other available antidepressants. It may cause fewer anticholinergic, antihistaminic, and antiadrenergic ADRs and may have a quicker onset of therapeutic action than existing antidepressants.