Association between the CYP2D6*4 polymorphism and depression or anxiety in the elderly

Beyond the label: current evidence and future directions for the interrelationship between electronic cigarettes and mental health

Electronic cigarette use has dramatically increased over the last decade. With this recent technological development and wide range of constituents in various products, putative adverse effects on the brain and body have been largely unexplored. Here, we review current evidence linking electronic nicotine cigarette use with potential health consequences and provide evidence supporting an association between drug use and depression in humans. We also examine the biological effects of individual constituents in electronic cigarette aerosols, which include labeled ingredients, such as propylene glycol, vegetable glycerin, nicotine, and flavorants, as well as unlabeled ingredients found in the aerosols, such as carbonyls and heavy metals. Lastly, we examine the effects of electronic cigarette use on endogenous metabolism via changes in cytochrome P450 enzymes, which can thereby impact therapeutic outcomes. While the current evidence offers insight into the potential effects of electronic cigarette use on biological processes, further studies are necessary to determine the long-term clinical relevance of aerosol inhalation.

Pharmacotherapy for the treatment of depression in patients with alzheimer's disease: a treatment-resistant depressive disorder

INTRODUCTION

Pharmacotherapy for the treatment of depressive disorders in Alzheimer's Disease (AD) represents a clinical challenge. pharmacological options are often attempted after a period of watchful waiting (8-12 weeks). monoaminergic antidepressant drugs have shown only modest or null clinical benefits, maybe because the etiology of depressive symptoms in ad patients is fundamentally different from that of nondemented subjects.

AREAS COVERED

The following article looks at the selective serotonin reuptake inhibitor sertraline, which is one of the most frequently studied antidepressant medications in randomized controlled trials (RCTs). It also discusses many other pharmacological approaches that have proven to be inadequate (antipsychotics, acetylcholinesterase inhibitors, anticonvulsants, hormone replacement therapy) and new drug classes (mainly affecting glutamate transmission) that are being studied for treating depression in AD. It also gives discussion to the phase II RCT on the alternative drug S47445 and the potential effect on cognition of the multimodal antidepressant vortioxetine in older depressed patients. Finally, it discusses the N-methyl-D-aspartate antagonist ketamine.

EXPERT OPINION

The present RCT methodologies are too disparate to draw firm conclusions. Future studies are required to identify effective and multimodal pharmacological treatments that efficiently treat depression in AD. Genotyping may boost antidepressant treatment success.

Antidepressants with a high serotonin reuptake transporter affinity and serum lipid levels in a population-based study in older adults

OBJECTIVE

We aimed to investigate the association between antidepressants and serum lipid levels in a population-based study in older adults.

METHODS

We included participants from the prospective Rotterdam Study with data on lipid levels (total, low-density lipoprotein (LDL) and high-density lipoprotein cholesterol, and triglycerides). We classified antidepressants based on binding affinity to the serotonin transporter (low/intermediate- and high-affinity antidepressants). We compared lipid levels in users of these groups of antidepressants with lipid levels in non-users. Furthermore, we studied effect modification by the 102 C>T polymorphism (HTR2A gene), which is associated with antidepressant drug response and metabolic outcomes.

RESULTS

Compared with non-users (N = 6438), LDL cholesterol level was higher (2.9 versus 3.1 mmol/L, respectively; p = 0.05) in users of high-affinity antidepressants (N = 89). Similar levels of the other lipids were observed between the groups for the other lipids. The mean difference in serum LDL cholesterol level between non-users and users of high-affinity antidepressants was largest in participants with the CC genotype compared with the other genotypes (notably 0.47 mmol/L), indicative of effect modification (p-value for interaction = 0.03).

CONCLUSION

Antidepressants with a high serotonin reuptake transporter affinity were associated with higher LDL cholesterol levels, which were modified by a common genetic variation in the HTR2A gene.

CYP2D6 variation, behaviour and psychopathology: implications for pharmacogenomics-guided clinical trials

Individual and population differences in polymorphic cytochrome P450 enzyme function have been known for decades. The biological significance of these differences has now been deciphered with regard to drug metabolism, action and toxicity as well as disposition of endogenous substrates, including neuroactive compounds. While the cytochrome P450 enzymes occur abundantly in the liver, they are expressed in most tissues of the body, albeit in varying amounts, including the brain. The latter location of cytochrome P450s is highly pertinent for susceptibility to neuropsychiatric diseases, not to mention local drug metabolism at the site of psychotropic drug action in the brain. In the current era of personality medicine with companion theranostics (i.e. the fusion of therapeutics with diagnostics), this article underscores that such versatile biological roles of cytochrome P450s offer multiple points of entry for personalized medicine and rational therapeutics. We focus our discussion on CYP2D6, one of the most intensively researched drug and endogenous compound metabolism pathways, with a view to relevance for, and optimization of, pharmacogenomic-guided clinical trials. Working on the premise that CYP2D6 is related to human behaviour and certain personality traits such as serotonin and dopamine system function, we further suggest that the motivation of healthy volunteers to participate in clinical trials may in part be influenced by an under- or over-representation of certain CYP2D6 metabolic groups.

CYP2D6 P34S Polymorphism and Outcomes of Escitalopram Treatment in Koreans with Major Depression

OBJECTIVE

Cytochrome P450 (CYP) enzymatic activity, which is influenced by CYP genetic polymorphism, is known to affect the inter-individual variation in the efficacy and tolerability of antidepressants in major depressive disorder (MDD). Escitalopram is metabolized by CYP2D6, and recent studies have reported a correlation between clinical outcomes and CYP2D6 genetic polymorphism. The purpose of this study was to determine the relationship between the CYP2D6 P34S polymorphism (C188T, rs1065852) and the efficacy of escitalopram treatment in Korean patients with MDD.

METHODS

A total of 94 patients diagnosed with MDD were recruited for the study and their symptoms were evaluated using the 21-item Hamilton Depression Rating scale (HAMD-21). The association between the CYP2D6 P34S polymorphism and the clinical outcomes (remission and response) was investigated after 1, 2, 4, 8, and 12 weeks of escitalopram treatment using multiple logistic regression analysis and χ(2) test.

RESULTS

The proportion of P allele carriers (PP, PS) in remission status was greater than that of S allele homozygotes (SS) after 8 and 12 weeks of escitalopram treatment. Similarly, P allele carriers exhibited a greater treatment response after 8 and 12 weeks of escitalopram treatment than S allele homozygotes.

CONCLUSION

Our results suggest that the P allele of the CYP2D6 P34S polymorphism is a favorable factor in escitalopram treatment for MDD, and that the CYP2D6 P34S polymorphism may be a good genetic marker for predicting escitalopram treatment outcomes.

Genetic variability of drug-metabolizing enzymes: the dual impact on psychiatric therapy and regulation of brain function

Polymorphic drug-metabolizing enzymes (DMEs) are responsible for the metabolism of the majority of psychotropic drugs. By explaining a large portion of variability in individual drug metabolism, pharmacogenetics offers a diagnostic tool in the burgeoning era of personalized medicine. This review updates existing evidence on the influence of pharmacogenetic variants on drug exposure and discusses the rationale for genetic testing in the clinical context. Dose adjustments based on pharmacogenetic knowledge are the first step to translate pharmacogenetics into clinical practice. However, also clinical factors, such as the consequences on toxicity and therapeutic failure, must be considered to provide clinical recommendations and assess the cost-effectiveness of pharmacogenetic treatment strategies. DME polymorphisms are relevant not only for clinical pharmacology and practice but also for research in psychiatry and neuroscience. Several DMEs, above all the cytochrome P (CYP) enzymes, are expressed in the brain, where they may contribute to the local biochemical homeostasis. Of particular interest is the possibility of DMEs playing a physiological role through their action on endogenous substrates, which may underlie the reported associations between genetic polymorphisms and cognitive function, personality and vulnerability to mental disorders. Neuroimaging studies have recently presented evidence of an effect of the CYP2D6 polymorphism on basic brain function. This review summarizes evidence on the effect of DME polymorphisms on brain function that adds to the well-known effects of DME polymorphisms on pharmacokinetics in explaining the range of phenotypes that are relevant to psychiatric practice.

CYP2D6 and the severity of suicide attempts

Aim: Among people who die by suicide, an increased frequency of CYP2D6 active gene multiplication has been described. Therefore, the present study analyzed the relationship between the severity of the suicidal intent and CYP2D6 number of active genes among survivors. Materials & methods: A group of 342 individuals were evaluated with Beck Suicide Intent Scale within 24 h of the failed attempt. ‘Severe’ suicide attempters were classified as those scoring above percentile 75 in the objective circumstances section of the Suicide Intent Scale Scale. A group of 377 healthy controls were also genotyped. Results: A higher number of ‘severe’ suicide attempters carrying ≥2 active CYP2D6 genes as compared with the rest of the patients population (p < 0.01) or the healthy control group (p < 0.01) was found. Conclusion: Considering that ‘severe’ suicide attempters are more likely eventually to die by suicide, CYP2D6 genetic polymorphism might be of use as a biomarker of death by suicide, which is in agreement with previous findings.

Original submitted: 17 July 2011; Revision submitted: 21 September 2011

CYP2D6 in the brain: genotype effects on resting brain perfusion

The cytochrome P450 2D6 (CYP2D6) is a genetically polymorphic enzyme involved in the metabolism of several psychoactive drugs. Beside its expression in the liver, CYP2D6 is highly expressed in several regions of the brain, such as the hippocampus, thalamus, hypothalamus and the cortex, but its function in the brain is not well understood. The CYP2D6 enzyme may also have a physiological role due to its involvement in neurotransmitter biotransformation. In this study, CYP2D6 genotyping was performed in N=188 healthy individuals and compared with brain perfusion levels at rest, which may reflect an ongoing biological process regulating the reactivity of the individual to emotional stimuli and the detection of signals evoking fear. Relative to N=42 matched extensive metabolizers, N=14 poor metabolizers were associated with 15% higher perfusion levels in the thalamus (P=0.03 and 0.003). Effects were also present in the whole (N=188) sample divided into metabolizer groups, or finely graded into seven CYP2D6 activity levels. A weaker effect was observed in the right hippocampus (P=0.05). An exploratory analysis, extended to the whole brain, suggested the involvement of CYP2D6 in regions associated with alertness or serotonergic function. These findings support the hypothesis of a functional role of CYP2D6 in the brain.

Drug metabolism within the brain changes drug response: selective manipulation of brain CYP2B alters propofol effects

Drug-metabolizing cytochrome P450 (CYPs) enzymes are expressed in the liver, as well as in extrahepatic tissues such as the brain. Here we show for the first time that drug metabolism by a CYP within the brain, illustrated using CYP2B and the anesthetic propofol (2, 6-diisopropylphenol, Diprivan), can meaningfully alter the pharmacological response to a CNS acting drug. CYP2B is expressed in the brains of animals and humans, and this CYP isoform is able to metabolize centrally acting substrates such as propofol, ecstasy, and serotonin. Rats were given intracerebroventricularly (i.c.v.) injections of vehicle, C8-xanthate, or 8-methoxypsoralen (CYP2B mechanism-based inhibitors) and then tested for sleep time following propofol (80 mg/kg intraperitoneally). Both inhibitors significantly increased sleep-time (1.8- to 2-fold) and brain propofol levels, while having no effect on plasma propofol levels. Seven days of nicotine treatment can induce the expression of brain, but not hepatic, CYP2B, and this induction reduced propofol sleep times by 2.5-fold. This reduction was reversed in a dose-dependent manner by i.c.v. injections of inhibitor. Sleep times correlated with brain (r=0.76, P=0.0009), but not plasma (r=0.24, P=0.39) propofol concentrations. Inhibitor treatments increased brain, but not plasma, propofol levels, and had no effect on hepatic enzyme activity. These data indicate that brain CYP2B can metabolize neuroactive substrates (eg, propofol) and can alter their pharmacological response. This has wider implications for localized CYP-mediated metabolism of drugs, neurotransmitters, and neurotoxins within the brain by this highly variable enzyme family and other CYP subfamilies expressed in the brain.