Response to Transdermal Selegiline Smoking Cessation Therapy and Markers in the 15q24 Chromosomal Region.

INTRODUCTION: Current treatments for smoking cessation have limited efficacy. A potential pharmaceutical treatment for smoking cessation is selegiline, a selective and irreversible monoamine oxidase B inhibitor. A few clinical trials have been carried out using selegiline but the results have been mixed. We sought to determine if genetic markers in cholinergic loci in the 15q24 chromosomal region predict response to smoking cessation therapy with selegiline. METHODS: We performed an 8-week double-blind, placebo-controlled clinical trial of the selegiline transdermal system in heavy smokers, with follow-up at weeks 25 and 52. Eight single nucleotide polymorphisms (SNPs) in the 15q24 region, which contains the genes for the nicotinic acetylcholine receptor subunits CHRNA5, CHRNA3, and CHRNB4, were investigated for association with treatment response. RESULTS: The CHRNB4 promoter SNP rs3813567 was associated with both point prevalence abstinence and post-quit craving. Carriers of the minor C allele treated with selegiline showed lower rates of abstinence and higher levels of craving than selegiline-treated non-carriers, indicating that the rs3813567 C allele adversely affects abstinence in selegiline-treated smokers. This effect was not present among placebo-treated smokers. Selegiline-treated smokers with the CHRNA5 rs680244 GG genotype had lower post-quit craving, and unlike placebo-treated GG-carrying smokers, did not experience a post-quit increase in depressive symptoms. CONCLUSIONS: Variants in genes encoding cholinergic receptors affect abstinence, craving and mood in selegiline-treated smokers. Selegiline primarily affects dopamine levels in the brain, but cholinergic input affects nicotine-induced dopaminergic activity. These markers may have value in identifying those likely to respond to selegiline for smoking cessation.

BDNF and CREB1 genetic variants interact to affect antidepressant treatment outcomes in geriatric depression.

AIM: Brain-derived neurotrophic factor (BDNF) is associated with antidepressant response on the cellular level, in animal models, and in clinical studies. A common variant in the BDNF gene results in a substitution of a methionine (Met) for a valine at the amino acid position 66. Previous studies reported that the Met variant results in enhanced response to antidepressant medications. These findings may be at odds with studies indicating that on a cellular level the Met variant impairs the secretion of BDNF. MATERIALS AND METHODS: We examined the effects of BDNF single nucleotide polymorphisms (SNPs) in response to the antidepressants paroxetine and mirtazapine in a sample of 246 geriatric patients with major depression, treated in a double-blind, randomized, 8-week clinical trial. We also examined the effects of genetic variation at the BDNF-related loci neurotrophic tyrosine kinase receptor 2, cyclic AMP responsive element binding protein 1 (CREB1), and CREB binding protein. A total of 53 SNPs were genotyped. RESULTS: BDNF genetic variation had a significant effect on the efficacy of paroxetine, with patients carrying the Met allele showing impaired response. SNPs at the CREB1 locus, which encodes a transcription factor important in BDNF signaling, also predicted response to paroxetine. Furthermore, we found a significant gene-gene interaction between BDNF and CREB1 that affected response to paroxetine. Because BDNF has been associated with cognitive function, we tested the effects of BDNF SNPs on change in a wide variety of cognitive tests over the 8-week trial, but there were no significant effects of genotype on cognition. CONCLUSION: These results provide new evidence for the importance of the BDNF pathway in antidepressant response in geriatric patients. The negative effect of the Met66 allele on antidepressant outcomes is consistent with basic science findings indicating a negative effect of this variant on BDNF activity in the brain. Further, the effect of BDNF genetic variation on antidepressant treatment is modified by variation in the gene encoding the downstream effector CREB1.

Markers in the 15q24 nicotinic receptor subunit gene cluster (CHRNA5-A3-B4) predict severity of nicotine addiction and response to smoking cessation therapy.

Stopping smoking is difficult even with treatment. Many patients prescribed pharmacologic treatments for smoking cessation experience side effects or lack of efficacy. We performed a pharmacogenetic study of the efficacy and tolerability of bupropion and transdermal nicotine (TN), two treatments for smoking cessation. Samples were drawn from two studies. In the first study (Maintenance 1, MT1), 301 smokers received bupropion plus TN for 11 weeks, followed by 14 weeks of placebo or bupropion. In the second study (MT2), 276 smokers received bupropion and TN for 8 weeks. We focused on eight SNPs in the 15q24 region, which contains the genes for the nicotinic cholinergic receptor subunits CHRNA5, CHRNA3, and CHRNB4, and has previously been implicated in nicotine addiction and smoking cessation. Analyses of baseline smoking quantity (SQ) identified an association between SQ and both the functional CHRNA5 SNP rs16969968 (D398N) and the CHRNA3 SNP rs1051730 (Y215Y) in a combined cohort containing MT1 and MT2. An association between SQ and ethnicity was also identified in the combined cohort. Pharmacogenetic analysis showed a significant association between rs8192475 (R37H) in CHRNA3 and both higher craving after quitting and increased withdrawal symptoms over time in MT2. Two markers for point prevalence abstinence, CHRNA5 SNP rs680244 and CHRNB4 SNP rs12914008, were also identified in MT2, with the strongest findings at week 52. These results provide further support for the role of the CHRNA5/A3/B4 subunits in determining number of cigarettes smoked and response to smoking cessation therapy.

ABCB1 (MDR1) polymorphisms and antidepressant response in geriatric depression.

OBJECTIVE: Variation in the ATP-binding cassette, subfamily B, member 1 transporter (ABCB1) (multidrug-resistance gene 1) gene has been investigated as a predictor of response to treatment with a variety of medications such as antiarrhythmics, chemotherapeutic agents, anti-HIV medications, and some psychotropics. The ABCB1 gene product, P-glycoprotein, affects the transport of drugs out of many cell types, including endothelial cells at the blood-brain barrier. We sought to determine if ABCB1 polymorphisms predict response to antidepressant treatment in geriatric patients. METHODS: We compared the effects of ABCB1 genetic variation on the therapeutic response to paroxetine, a P-glycoprotein substrate, and to mirtazapine, which is not thought to be transported by ABCB1, in a sample of 246 elderly patients with major depression treated in a clinical trial setting. A total of 15 single nucleotide polymorphisms in the ABCB1 gene were assessed in each patient. Two of these ABCB1 single nucleotide polymorphisms were earlier reported to predict treatment response in patients prescribed with P-glycoprotein substrate antidepressants. RESULTS: The two earlier identified ABCB1 markers for antidepressant response predicted time to remission in our paroxetine-treated patients, but not in the mirtazapine-treated patients. These results replicate the published findings of others. If a Bonferroni correction for type I error is made, our results do not reach the criteria for statistical significance. However, the Bonferroni correction may be too conservative given the strong linkage disequilibrium among some of the markers and our aim to replicate the earlier published findings. CONCLUSION: Our study provides confirmation that certain ABCB1 polymorphisms predict response to substrate medications in geriatric patients.

FKBP5 polymorphisms and antidepressant response in geriatric depression.

Genetic variation at the FKBP5 locus has been reported to affect clinical outcomes in patients treated with antidepressant medications in several studies. However, other reports have not confirmed this association. FKBP5 may regulate the sensitivity of the hypothalamic-pituitary-adrenal axis. We tested two FKBP5 single nucleotide polymorphisms (rs1360780 and rs3800373) in a sample of 246 geriatric patients treated for 8 weeks in a double-blind randomized comparison trial of paroxetine and mirtazapine. These two polymorphisms had previously been reported to predict efficacy in depressed patients treated with selective serotonin reuptake inhibitors such as paroxetine, and those treated with mirtazapine, an agent with both serotonergic and noradrenergic actions. However, we found no significant associations between these FKBP5 genetic variants and clinical outcomes. Neither mean Hamilton Depression Rating Scale scores nor time to remission or response were predicted by FKBP5 genetic variation. These results suggest that FKBP5 is unlikely to play a major role in determining antidepressant treatment outcomes in geriatric patients.

Slower speed-of-processing of cognitive tasks is associated with presence of the apolipoprotein epsilon4 allele.

Detection of preclinical cognitive deficits is important for identifying those at greatest risk for such disorders as Alzheimer's disease. However, available neuropsychological measures may not be sufficiently sensitive to preclinical cognitive impairment, particularly in high functioning or younger older adults. This study utilizes a battery of computerized cognitive tests (Cognometer) designed to provide a more sensitive measure of age-related cognitive performance by incorporating speed-of-processing components. Fifty-one community-dwelling older adults were administered the Cognometer battery, which incorporates speed-of-processing components into measures of verbal, spatial and working memory, attention, and visuo-spatial ability. Performance of 18 subjects with the epsilon4 allele was compared to that of 33 subjects without the epsilon4 allele. A brief battery of standard neuropsychological measures was also administered. No significant differences were observed between the two groups with respect to performance on any of the neuropsychological measures. However, with respect to the Cognometer battery, individuals with the epsilon4 allele were significantly slower in performing all the cognitive tasks, with the exception of the visuo-spatial task. With respect to performance, the two genotype groups did not differ significantly except on immediate memory, with the epsilon4 group exhibiting increased errors. Overall, the epsilon4 group was significantly slower in performing all of the Cognometer memory tasks. These findings provide continued support for the negative impact of the epsilon4 allele on cognition and further suggest that speed-of-processing during memory tasks may have the potential to detect subtle cognitive deficits.

Extended cognitive behavior therapy for cigarette smoking cessation.

UNLABELLED: PRIMARY AIM: Examine the effectiveness of extended cognitive behavior therapy (CBT) in promoting longer-term smoking abstinence. DESIGN: Open-label treatment phase followed by extended treatment phase. Randomization conducted prior to entry into open-label treatment phase; analysis based on intention-to-treat to avoid threat of selection bias. SETTING: Community smoking cessation clinic. PARTICIPANTS: A total of 304 adult smokers (> or = 18 years of age; > or = 10 cigarettes/day). INTERVENTION: Open-label (8 weeks): all participants received bupropion SR, nicotine patch, CBT. Extended treatment (12 weeks): participants received either CBT + voicemail monitoring and telephone counseling or telephone-based general support. MEASUREMENTS: Seven-day point prevalence abstinence, expired-air carbon monoxide. RESULTS: At week 20 follow-up, CBT produced a higher 7-day point prevalence abstinence rate: 45% versus 29%, P = 0.006; at 52 weeks the difference in abstinence rates (31% versus 27%) was not significant. History of depression was a moderator of treatment. Those with a positive history had a better treatment response at 20 weeks when assigned to the less intensive telephone support therapy (P < 0.05). CONCLUSION: The superiority of CBT to 20 weeks suggests that continued emphasis on the development of cognitive and behavioral strategies for maintaining non-smoking during an extended treatment phase may help smokers to maintain abstinence in the longer term. At present, the minimum duration of therapy is unknown.

Corticotropin-releasing factor 1 receptor haplotype and cognitive features of major depression.

Corticotropin-releasing factor signaling through CRF receptor type 1 (CRF1) has been shown to contribute to learning and memory function. A haplotype of alleles T-A-T in a set of common polymorphisms in the gene encoding for CRF1 (CRHR1) has been associated with both depression vulnerability and alterations in cognitive functioning. The present study investigated the relations between the TAT haplotype and specific symptoms of depression, self-reported ruminative behaviors, and neuropsychological performance on a learning and memory task. Participants were adults with major depression with and without psychotic features (N = 406). Associations were examined between TAT haplotype and endorsement of depression symptoms from diagnostic interviews, scores on the rumination response scale (RRS), and verbal memory performance on the California Verbal Learning Test-II (CVLT-II). All analyses included depression subtype, age, and sex as covariates; CVLT-II analyses also included evening cortisol levels. Across the entire sample, carriers of more copies of the TAT haplotype reported greater endorsement of the symptom describing difficulty concentrating and making decisions. In separate subsamples, TAT homozygotes had higher rumination scores on the RRS, both brooding and reflection subscales, and more TAT copies were associated with poorer CVLT-II performance in both total learning and free recall trials. These data demonstrate that the CRHR1 TAT haplotype is associated with cognitive features of depression including difficulty with decision-making, higher rumination, and poorer learning and memory. It will be important in future research to identify the specific molecular mechanisms for CRF1 signaling that contribute to depression-related cognitive dysfunction.

A novel quantitative trait locus on mouse chromosome 18, "era1," modifies the entrainment of circadian rhythms.

STUDY OBJECTIVE: The mammalian circadian clock in the suprachiasmatic nuclei (SCN) of the hypothalamus conveys 24-h rhythmicity to sleep-wake cycles, locomotor activity, and other behavioral and physiological processes. The timing of rhythms relative to the light/dark (LD12:12) cycle is influenced in part by the endogenous circadian period and the time of day specific sensitivity of the clock to light. We now describe a novel circadian rhythm phenotype, and a locus influencing that phenotype, in a segregating population of mice. METHODS: By crossbreeding 2 genetically distinct nocturnal strains of mice (Cast/Ei and C57BL/6J) and backcrossing the resulting progeny to Cast/Ei, we have produced a novel circadian phenotype, called early runner mice. RESULTS: Early runner mice entrain to a light/dark cycle at an advanced phase, up to 9 hours before dark onset. This phenotype is not significantly correlated with circadian period in constant darkness and is not associated with disruption of molecular circadian rhythms in the SCN, as assessed by analysis of period gene expression. We have identified a genomic region that regulates this phenotype-a major quantitative trait locus on chromosome 18 (near D18Mit184) that we have named era1 for Early Runner Activity locus one. Phase delays caused by light exposure early in the subjective night were of smaller magnitude in backcross offspring that were homozygous Cast/Ei at D18Mit184 than in those that were heterozygous at this locus. CONCLUSION: Genetic variability in the circadian response to light may, in part, explain the variance in phase angle of entrainment in this segregating mouse population.

Microglia overexpressing the macrophage colony-stimulating factor receptor are neuroprotective in a microglial-hippocampal organotypic coculture system.

Microglia with increased expression of the macrophage colony-stimulating factor receptor (M-CSFR; c-fms) are found surrounding plaques in Alzheimer's disease (AD) and in mouse models for AD and after ischemic or traumatic brain injury. Increased expression of M-CSFR causes microglia to adopt an activated state that results in proliferation, release of cytokines, and enhanced phagocytosis. To determine whether M-CSFR-induced microglial activation affects neuronal survival, we assembled a coculture system consisting of BV-2 microglia transfected to overexpress the M-CSFR and hippocampal organotypic slices treated with NMDA. Twenty-four hours after assembly of the coculture, microglia overexpressing M-CSFR proliferated at a higher rate than nontransfected control cells and exhibited enhanced migration toward NMDA-injured hippocampal cultures. Surprisingly, coculture with c-fms-transfected microglia resulted in a dramatic reduction in NMDA-induced neurotoxicity. Similar results were observed when cocultures were treated with the teratogen cyclophosphamide. Biolistic overexpression of M-CSFR on microglia endogenous to the organotypic culture also rescued neurons from excitotoxicity. Furthermore, c-fms-transfected microglia increased neuronal expression of macrophage colony-stimulating factor (M-CSF), the M-CSFR, and neurotrophin receptors in the NMDA-treated slices, as determined with laser capture microdissection. In the coculture system, direct contact between the exogenous microglia and the slice was necessary for neuroprotection. Finally, blocking expression of the M-CSF ligand by exogenous c-fms-transfected microglia with a hammerhead ribozyme compromised their neuroprotective properties. These results demonstrate a protective role for microglia overexpressing M-CSFR in our coculture system and suggest under certain circumstances, activated microglia can help rather than harm neurons subjected to excitotoxic and teratogen-induced injury.

The brain-derived neurotrophic factor Val66Met polymorphism and rate of decline in Alzheimer's disease.

It is largely unknown why some patients with Alzheimer's disease (AD) decline cognitively more rapidly than others. Genetic differences among patients could influence rate of decline. Brain-derived neurotrophic factor (BDNF) is a neurotrophin important in the survival neurons and in memory function. BDNF levels are reduced in the brain in AD. The Val66Met polymorphism in the BDNF gene modifies neuronal BDNF secretion, and affects hippocampal function and memory performance. We tested the hypothesis that the BDNF Val66Met polymorphism influences rate of cognitive decline in AD. In a sample of 149 AD patients followed for an average of 3.9 years, we found no effect of BDNF Val66Met genotype on rate of change in the Mini Mental State Examination. Results were similar when we excluded patients taking an acetylcholinesterase inhibitor, those placed in a nursing home during the study, or those with a neuropathological diagnosis that included AD plus an entity other than AD. We also found no evidence that the effects of the BDNF Val66Met genotype depend on APOE genotype, which itself had no effect on rate of cognitive change. These findings suggest that the functional BDNF Val66Met variant is not a major determinant of rate of cognitive decline in AD.

Extended treatment with bupropion SR for cigarette smoking cessation.

The authors present results of a randomized clinical trial of the efficacy of extended treatment with bupropion SR in producing longer term cigarette smoking cessation. Adult smokers (N = 362) received open-label treatment (11 weeks) that combined relapse prevention training, bupropion SR, and nicotine patch followed by extended treatment (14 weeks) with bupropion SR or matching placebo. Abstinence percentages were relatively high (week 11: 52%; week 25: bupropion, 42%; placebo, 38%; week 52: bupropion, 33%; placebo, 34%), but bupropion SR did not surpass placebo. Gender and baseline craving level were identified as significant, independent moderators of treatment response. Men were more likely to abstain than women (week 11: 59% vs. 43%, p = .001; week 25: 48% vs. 31%, p = .001; week 52: 39% vs. 27%, p = .01). Because most smokers suffer relapse with any current cessation treatment, the comparatively high abstinence percentages achieved in this trial are of interest.

Application of microarray technology in psychotropic drug trials.

Microarrays can be manufactured to detect hundreds of thousands of polymorphisms in DNA from patients in psychotropic drug trials. Some of these polymorphisms may be useful as pharmacogenetic predictors of treatment outcomes. We tested a microarray designed to detect common polymorphisms in the CYP2D6 gene that encodes debrisoquine hydroxylase (DH). DH is involved in the hepatic metabolism of many psychotropics. CYP2D6 genotypes predicted plasma steady state concentrations of nortriptyline, a classic DH substrate, in a sample of geriatric patients with major depression. However, in a sample of 246 geriatric patients treated with paroxetine or mirtazapine, both of which are metabolized in part by DH, CYP2D6 genotypes determined with microarrays did not predict discontinuations due to adverse events or severity of adverse events. For modern antidepressants such as paroxetine and mirtazapine, pharmacokinetic factors that are regulated by CYP2D6 such as plasma drug concentrations may be less important than pharmacodynamic factors in determining outcomes. Studies of single candidate genes such as CYP2D6 have only begun to utilize the potential of microarrays for pharmacogenetic prediction. Yet, there is controversy as to whether genome-wide studies designed to detect millions of genotypes with microarrays will lead to new pharmacogenetic discoveries, or whether a more focused, hypothesis-driven approach is better.

Effects of the serotonin transporter gene promoter polymorphism on mirtazapine and paroxetine efficacy and adverse events in geriatric major depression.

BACKGROUND: The "long/short"polymorphism (5HTTLPR) in the promoter of the serotonin transporter gene (SLC6A4) has been proposed as a pharmacogenetic marker for antidepressant efficacy. Some but not all studies have found that the short form of 5HTTLPR (S allele) results in decreased efficacy of selective serotonin reuptake inhibitors. OBJECTIVE: To determine if the 5HTTLPR polymorphism influences the efficacy and tolerability of mirtazapine and paroxetine hydrochloride, 2 frequently prescribed antidepressants with differing pharmacologic profiles, in geriatric depression. DESIGN: Double-blind, randomized 8-week study. SETTING: Eighteen academic and private outpatient clinics. PATIENTS: We evaluated 246 cognitively intact patients 65 years or older with major depression. INTERVENTIONS: Antidepressant therapy with 15 to 45 mg/d of mirtazapine (n = 124) or 20 to 40 mg/d of paroxetine (n = 122). MAIN OUTCOME MEASURES: The Hamilton Depression Rating Scale-17 and Geriatric Depression Scale, severity of adverse events and dosing compliance indexes, and discontinuations due to adverse events. Outcome measures were stratified according to 5HTTLPR genotypes. RESULTS: Geriatric Depression Scale scores indicated that S allele carriers treated with paroxetine showed a small impairment in antidepressant response. Among mirtazapine-treated patients, there was little indication that the 5HTTLPR genotype affected antidepressant efficacy. However, the 5HTTLPR polymorphism had a dramatic effect on adverse events. Among paroxetine-treated subjects, S allele carriers experienced more severe adverse events during the course of the study, achieved significantly lower final daily doses, and had more discontinuations at days 14, 21, 28, 42, and 49. Surprisingly, among mirtazapine-treated subjects, S allele carriers had fewer discontinuations due to adverse events, experienced less severe adverse events, and achieved higher final daily doses. CONCLUSIONS: These results support the hypothesis that the S allele of 5HTTLPR at the SLC6A4 locus is associated with a poor outcome after treatment with selective serotonin reuptake inhibitors. However, the major effect was on the tolerability of these drugs rather than efficacy. Results from mirtazapine-treated patients indicate that the effect of this polymorphism on outcome may depend on the mechanism of antidepressant action.

ABCB1 Genetic Effects on Antidepressant Outcomes: A Report From the iSPOT-D Trial.

OBJECTIVE: The ABCB1 gene encodes P-glycoprotein, which limits brain concentrations of certain antidepressants. ABCB1 variation has been associated with antidepressant efficacy and side effects in small-sample studies. Cognitive impairment in major depressive disorder predicts poor treatment outcome, but ABCB1 genetic effects in patients with cognitive impairment are untested. The authors examined ABCB1 genetic variants as predictors of remission and side effects in a large clinical trial that also incorporated cognitive assessment. METHOD: The authors genotyped 10 ABCB1 single-nucleotide polymorphisms (SNPs) in 683 patients with major depressive disorder treated for at least 2 weeks, of whom 576 completed 8 weeks of treatment with escitalopram, sertraline, or extended-release venlafaxine (all substrates for P-glycoprotein) in a large randomized, prospective, pragmatic trial. Antidepressant efficacy was assessed with the 16-item Quick Inventory of Depressive Symptomatology-Self-Rated (QIDS-SR), and side effects with a rating scale for frequency, intensity, and burden of side effects. General and emotional cognition was assessed with a battery of 13 tests. RESULTS: The functional SNP rs10245483 upstream from ABCB1 had a significant effect on remission and side effect ratings that was differentially related to medication and cognitive status. Common homozygotes responded better and had fewer side effects with escitalopram and sertraline. Minor allele homozygotes responded better and had fewer side effects with venlafaxine, with the better response most apparent for patients with cognitive impairment. CONCLUSIONS: The functional polymorphism rs10245483 differentially affects remission and side effect outcomes depending on the antidepressant. The predictive power of the SNP for response or side effects was not lessened by the presence of cognitive impairment.

The apolipoprotein E epsilon4 allele and antidepressant efficacy in cognitively intact elderly depressed patients.

BACKGROUND: Patients vary in response to antidepressant medications. Apolipoprotein E (APOE) genotype affects vulnerability to stress and risk for cognitive impairment. We sought to determine if the APOE epsilon4 allele influences response in geriatric depression to mirtazapine and paroxetine, two frequently prescribed antidepressants. We hypothesized that epsilon4 carriers would show impaired antidepressant response. METHODS: The study was a double-blind, randomized, 8-week trial with a 16-week extension phase involving 246 cognitively intact patients aged 65 years or older with major depression. Patients were treated with mirtazapine 15-45 mg (n = 124) or paroxetine 20-40 mg (n = 122). The outcome measures were the Hamilton Depression Rating Scale, the Geriatric Depression Scale, and the Clinical Global Impression Scale. APOE genotype was determined by restriction isotyping. RESULTS: Patients carrying the epsilon4 allele showed a rapid onset of mirtazapine action, whereas paroxetine-treated patients with the epsilon4 allele were slow to respond. This difference could not be attributed to dosage, compliance, severity of adverse events, ethnicity, baseline depression or cognition, gender, or age. CONCLUSIONS: The APOE epsilon4 allele may affect antidepressant treatment outcome, but the effect depends on the medication. Further studies should determine if this result applies to other samples and medications.

Developing novel treatments for mood disorders: accelerating discovery.

This review was generated from discussions by the Pharmacologic and Somatic Treatments Section of the National Institute of Mental Health Strategic Plan for Mood Disorders Committee on advancing novel pharmacologic and somatic treatments for mood disorders. The opening section of the article summarizes in broad strokes, current pharmacologic treatments, and new directions in the field. Thereafter the topics focus on specific research initiatives that could advance the current therapeutics for mood disorders including new basic and clinical research in vivo human imaging procedures, somatic therapeutics, and the vast new area of pharmacogenetics. New scientific and technical opportunities exist today based on advances in basic neuroscience, opportunities in clinical testing, industry interest in advancing central nervous system therapeutics, and on active consumer advocacy groups. The question of how to bring all of these positive forces together to accelerate discovery in mood disorder thera-peutics is the topic of this article.

Microglial overexpression of the M-CSF receptor augments phagocytosis of opsonized Abeta.

The role of microglia in Alzheimer's disease (AD) has come under intense scrutiny recently because microglia may clear amyloid beta (Abeta) by phagocytosis after immunization of transgenic mice. Increased expression of the macrophage colony-stimulating factor receptor (M-CSFR) is an important feature of microglia in AD and transgenic mouse models for AD. Increased expression of M-CSFR on mouse and human microglia accelerates phagocytosis of aggregated Abeta in part through macrophage scavenger receptors. We now show that Abeta phagocytosis by microglia overexpressing M-CSFR is further enhanced by antibody opsonization of Abeta. M-CSFR overexpression increased microglial phagocytosis of opsonized aggregated Abeta in culture medium, and accelerated ingestion of native Abeta from AD brain sections. M-CSFR overexpression also increased microglial expression of Fcgamma receptors, and blocking Fcgamma receptors attenuated the enhanced Abeta uptake observed after M-CSFR overexpression and antibody opsonization. Microglia in AD and in AD mouse models with increased expression of M-CSFR are likely to rapidly ingest opsonized Abeta after immunization, making high intracerebral antibody titers unnecessary.

Proinflammatory effects of M-CSF and A beta in hippocampal organotypic cultures.

Macrophage colony stimulating factor (M-CSF) is a microglial activator expressed at increased levels in the brain in Alzheimer's disease. In monotypic microglial cultures, M-CSF strongly augments amyloid beta (Abeta) induced microglial production of proinflammatory cytokines and nitric oxide. However, this augmentation could be due to strong autocrine and paracrine effects in monotypic cultures. We used hippocampal organotypic cultures to test M-CSF/Abeta augmentation in a system modeling intact brain. Combined M-CSF/Abeta treatment increased interleukin-1 (IL-1) and macrophage inflammatory protein 1-alpha expression by microglia, whereas inducible nitric oxide synthase (iNOS) expression was localized primarily to astroglia. Induction of cytokines and iNOS was also observed after lipopolysaccharide treatment of organotypic hippocampal cultures, but iNOS expression was localized mainly to microglia rather than astrocytes. Treatment with M-CSF/Abeta did not result in neuronal death. These results demonstrate that combined M-CSF/Abeta treatment results in a strong inflammatory response in the organotypic environment without inducing neurotoxicity.

Pharmacogenetics of antidepressant medication intolerance.

OBJECTIVE: The authors sought to identify genetic markers for antidepressant medication intolerance. Genetic variation in drug metabolizing enzymes such as cytochrome P450 2D6 (CYP2D6) has been postulated to underlie antidepressant intolerance (pharmacokinetic effect). However, variation in genes encoding serotonin receptors could also explain antidepressant side effects (pharmacodynamic effect). METHOD: An 8-week, double-blind, randomized pharmacogenetic study compared the widely prescribed antidepressants paroxetine (a selective serotonin reuptake inhibitor [SSRI]) and mirtazapine (not an SSRI) in 246 elderly patients with major depression. Genotypes were determined for the 102 T/C single nucleotide polymorphism (SNP) in the serotonin 2A (5-HT(2A)) locus (HTR2A), previously associated with psychotropic medication treatment outcome. Oligonucleotide microarrays were used to extensively characterize variation in the CYP2D6 gene. Clinical outcomes included treatment discontinuations, adverse events, medication compliance, and change in mood. RESULTS: Survival analysis showed discontinuations due to paroxetine-induced side effects were strongly associated with the HTR2A C/C genotype. There was a significant linear relationship between the number of C alleles and the probability of discontinuation. Side effect severity in paroxetine-treated patients with the C/C genotype was also greater. In contrast, HTR2A 102 T/C genotype had no effect on mirtazapine side effects. CYP2D6 genotype did not predict treatment outcome for either medication. CONCLUSIONS: Pharmacodynamic differences among patients due to variant 5-HT(2A) receptors appear to be more important than pharmacokinetic variation in determining paroxetine intolerance. Pharmacogenetic markers may be useful in predicting antidepressant treatment outcome.