Francesco Benedetti

Polymorphism within the promoter of the serotonin transporter gene and antidepressant efficacy of fluvoxamine

Depression with psychotic features has been shown to respond to selective serotonin reuptake inhibitors (SSRIs). The serotonin transporter (5-HTT) is a prime target for SSRIs. A functional polymorphism within the promoter region of the 5-HTT gene, leading to different transcriptional efficiency, was recently reported. We tested the hypothesis that allelic variation of the 5-HTT promoter could be related to the antidepressant response to fluvoxamine and/or augmentation with pindolol (a serotonin autoreceptors antagonist) which has been suggested as an augmentation therapy for nonresponders. One hundred and two inpatients with major depression with psychotic features were randomly assigned to treatment with a fixed dose of fluvoxamine and either placebo or pindolol for 6 weeks. Depression severity was assessed once a week using the Hamilton Depression Rating Scale. Allelic variation in each subject was determined using a PCR-based method. Data were analyzed with a three-way repeated measures analysis of variance. Both homozygotes for the long variant (l/l) of the 5-HTT promoter and heterozygotes (l/s) showed a better response to fluvoxamine than homozygotes for the short variant (s/s). In the group treated with fluvoxamine plus pindolol all the genotypes acted like l/l treated with fluvoxamine alone. Fluvoxamine efficacy in delusional depression seems to be related to allelic variation within the promoter of the 5-HTT gene. Even though other factors may be implicated, genotyping at 5-HTT promoter may represent a promising tool to individualize the pharmacological treatment of depression.

Influence of CLOCK gene polymorphism on circadian mood fluctuation and illness recurrence in bipolar depression.

Recent studies showed that a polymorphism (T to C nucleotide substitution) in the 3′ flanking region of the human CLOCK gene is associated with diurnal preferences of human healthy subjects, with higher “eveningness” in subjects carrying at least one copy of the C allele. We investigated the possible role of CLOCK gene polymorphism in the regulation of diurnal mood fluctuations during a major depressive episode. Sample (n = 101) was collected, in the context of previously reported trials, among patients affected by bipolar disorder type I, depressive episode without psychotic features, free of psychotropic medications. Perceived mood levels were assessed three times a day with self‐administered visual analogue scales. Genotype groups showed no significant difference in diurnal mood fluctuations. When stratifying the sample by including only patients with an adequate period of observation (duration of illness higher than 5 years, n = 69), we post‐hoc observed a significantly higher recurrence rate in homozygotes for the C variant, which was almost double than that of the other genotype groups. This preliminary observation leads to hypothesize a role for the CLOCK gene polymorphism in the regulation of long‐term illness recurrence in bipolar disorder. Given the post‐hoc nature of the finding, replication in independent samples is necessary to confirm it.

Genetic dissection of psychopathological symptoms: Insomnia in mood disorders and CLOCK gene polymorphism

We investigated the possible effect of the 3111T/C CLOCK gene polymorphism on sleep disorders in a sample of 620 patients affected by major depressive disorder (MDD) and bipolar disorder (BP). We detected a significantly higher recurrence of initial (P = 0.0001), middle (P = 0.0009), and early (P = 0.0008) insomnia in homozygotes for the C variant and a similar trend concerning decreased need of sleep in BP (P = 0.0074). Other demographic and clinical features were found not related with CLOCK polymorphisms. This preliminary observation leads to hypothesize a possible involvement of the CLOCK gene polymorphism in the sleep disregulations in MDD and BP. Copyright

Rate of switch from depression into mania after therapeutic sleep deprivation in bipolar depression

Sleep deprivation is a potentially useful non-pharmacological treatment for depression. A relationship between sleep loss and the onset of mania has been reported, so it is possible that a switch from depression into mania after sleep deprivation might be expected in bipolar depressed patients who are treated with sleep deprivation. In a sample of 206 bipolar depressed treated with three cycles of sleep deprivation, alone or in combination with heterogeneous medications, we observed a 4.85% switch rate into mania and a 5.83% switch rate into hypomania. These percentages are comparable to those observed with antidepressant drug treatments.

Chronotherapeutics (light and wake therapy) in affective disorders

The Committee on Chronotherapeutics, delegated by the International Society for Affective Disorders (ISAD), makes the following recommendations after reviewing the evidence as of November 2004. (1) Wake therapy is the most rapid antidepressant available today: approximately 60% of patients, independent of diagnostic subtype, respond with marked improvement within hours. Treatment can be a single or repeated sleep deprivation, total (all night) or partial (second half of the night). Relapse can be prevented by daily light therapy, concomitant administration of SSRIs, lithium (for bipolar patients), or a short phase advance of sleep over 3 days following a single night of wake therapy. Combinations of these interventions show great promise. (2) Light therapy is effective for major depression--not only for the seasonal subtype. As an adjuvant to conventional antidepressants in unipolar patients, or lithium in bipolar patients, morning light hastens and potentiates the antidepressant response. Light therapy shows benefit even for patients with chronic depression of 2 years or more, outperforming their weak response to drugs. This method provides a viable alternative for patients who refuse, resist or cannot tolerate medication, or for whom drugs may be contraindicated, as in antepartum depression. (3) Given the urgent need for new strategies to treat patients with residual depressive symptoms, clinical trials of wake therapy and/or adjuvant light therapy, coupled with follow-up studies of long-term recurrence, are a high priority.

Morning sunlight reduces length of hospitalization in bipolar depression

BACKGROUND Bright artificial light improves non-seasonal depression. Preliminary observations suggest that sunlight could share this effect. METHODS Length of hospitalization was recorded for a sample of 415 unipolar and 187 bipolar depressed inpatients, assigned to rooms with eastern (E) or western (W) windows. RESULTS Bipolar inpatients in E rooms (exposed to direct sunlight in the morning) had a mean 3.67-day shorter hospital stay than patients in W rooms. No effect was found in unipolar inpatients. CONCLUSIONS Natural sunlight can be an underestimated and uncontrolled light therapy for bipolar depression. LIMITATIONS This is a naturalistic retrospective observation, which needs to be confirmed by prospective studies.

Long-term response to lithium salts in bipolar illness is influenced by the glycogen synthase kinase 3-β-50 T/C SNP

The molecular mechanisms driving the biological clock in the suprachiasmatic nucleus of the hypothalamus may play a role in mood disorders. A single nucleotide polymorphism (SNP) (-50 T/C) falling into the effective promoter region (nt -171 to +29) of the gene coding for glycogen synthase kinase 3-beta (GSK3-beta) has been linked with different age at onset of bipolar illness and with different antidepressant effects of total sleep deprivation. GSK3-beta codes for an enzyme which is a target for the action of lithium and possibly of valproic acid. We studied the effect of this polymorphism on the therapeutic response to lithium salts of 88 bipolar type I patients. Data about recurrence rate of mood episodes were collected for at least 2 years before lithium and 2 years on lithium. Results showed that homozygotes for the wild variant did not change their recurrence index while carriers of the mutant allele improved, thus supporting the hypothesis that GSK is a target for the therapeutic action of lithium. Results warrant interest for the variants of genes pertaining to the molecular clock as possible endophenotypes of bipolar disorder, but caution ought to be taken in interpreting these preliminary results and future replication studies must be awaited because of the low frequency of the GSK3-beta*C/C genotype in the studied populations.

A single nucleotide polymorphism in glycogen synthase kinase 3-β promoter gene influences onset of illness in patients affected by bipolar disorder

Genetic studies in medicine exploited age of onset as a criterion to delineate subgroups of illness. Bipolar patients stratified with this criterion were shown to share clinical characteristics and patterns of inheritance of illness. The molecular mechanisms driving the biological clock in the suprachiasmatic nucleus of the hypothalamus may play a role in mood disorders. A single nucleotide polymorphism (SNP) (-50 T/C) falling into the effective promoter region (nt -171 to +29) of the gene coding for glycogen synthase kinase 3-beta (GSK3-beta) has been identified. GSK3-beta codes for an enzyme which is a target for the action of lithium and which is also known to regulate circadian rhythms in Drosophila. We studied the effect of this polymorphism on the age at onset of bipolar disorder type I. A homogeneous sample of 185 Italian patients affected by bipolar disorder was genotyped. Age at onset was retrospectively ascertained with best estimation procedures. No association was detected between GSK3-beta -50 T/C SNP and the presence of bipolar illness. Homozygotes for the wild variant (T/T) showed an earlier age at onset than carriers of the mutant allele (F=5.53, d.f.=2,182, P=0.0047). Results warrant interest for the variants of genes pertaining to the molecular clock as possible endophenotypes of bipolar disorder, but caution ought to be taken in interpreting these preliminary results and future replication studies must be awaited.

Actimetric evidence that CLOCK 3111 T/C SNP influences sleep and activity patterns in patients affected by bipolar depression.

Depressive insomnia and diurnal fluctuations of mood and activity are core clinical features of mood disorders. Here we studied the effect of CLOCK 3111 T/C SNP (rs1801260) on the actimetric recorded diurnal activity and nocturnal sleep of 39 bipolar depressed inpatients. Compared to T/T homozygotes, carriers of the C allele had a similar degree of severity of depression, but showed higher activity levels in the evening, a delayed sleep onset (mean 79 min later), and a reduced amount of sleep during the night (mean 75 min less). Ongoing lithium treatment significantly interacted with rs1801260 by enhancing activity levels in the evening and reducing the differences among genotype groups. Individual characteristics of the molecular clock can influence sleep symptoms in mood disorders.

A glycogen synthase kinase 3-β promoter gene single nucleotide polymorphism is associated with age at onset and response to total sleep deprivation in bipolar depression

The molecular mechanisms driving the biological clock in the suprachiasmatic nucleus of the hypothalamus may play a role in mood disorders. A single nucleotide polymorphism (SNP) (-50T/C) falling into the effective promoter region (nt -171 to +29) of the gene coding for glycogen synthase kinase 3-beta (GSK3-beta) has been linked with different age at onset of bipolar illness. GSK3-beta codes for an enzyme which is a target for the action of lithium and valproic acid, and the inhibition of which causes antidepressant-like behaviors in a preclinical model. We studied the effect of this polymorphism on the acute response to total sleep deprivation of 60 depressed bipolar type I inpatients. Homozygotes for the mutant allele of GSK3-beta promoter (-50T/C) SNP showed a later onset of bipolar illness, and better acute effects of TSD treatment on perceived mood (as rated on VAS). Overall, these observations suggest a protective role for this genotype in respect to bipolar illness. Results warrant interest for the variants of genes pertaining to the molecular clock as possible endophenotypes of bipolar disorder, and for GSK3-beta as a target of a new class of antidepressant drugs, but caution ought to be taken in interpreting these preliminary results and future replication studies must be awaited because of the low frequency of the GSK3-beta*C/C genotype in the studied populations.