Roy H. Perlis

Molecular genetics of attention-deficit/hyperactivity disorder.

Results of behavioral genetic and molecular genetic studies have converged to suggest that both genetic and nongenetic factors contribute to the development of attention-deficit/hyperactivity disorder (ADHD). We review this literature, with a particular emphasis on molecular genetic studies. Family, twin, and adoption studies provide compelling evidence that genes play a strong role in mediating susceptibility to ADHD. This fact is most clearly seen in the 20 extant twin studies, which estimate the heritability of ADHD to be .76. Molecular genetic studies suggest that the genetic architecture of ADHD is complex. The few genome-wide scans conducted thus far are not conclusive. In contrast, the many candidate gene studies of ADHD have produced substantial evidence implicating several genes in the etiology of the disorder. For the eight genes for which the same variant has been studied in three or more case-control or family-based studies, seven show statistically significant evidence of association with ADHD on the basis of the pooled odds ratio across studies: DRD4, DRD5, DAT, DBH, 5-HTT, HTR1B, and SNAP-25.

Identification of risk loci with shared effects on five major psychiatric disorders: a genome-wide analysis

BACKGROUND: Findings from family and twin studies suggest that genetic contributions to psychiatric disorders do not in all cases map to present diagnostic categories. We aimed to identify specific variants underlying genetic effects shared between the five disorders in the Psychiatric Genomics Consortium: autism spectrum disorder, attention deficit-hyperactivity disorder, bipolar disorder, major depressive disorder, and schizophrenia. METHODS: We analysed genome-wide single-nucleotide polymorphism (SNP) data for the five disorders in 33,332 cases and 27,888 controls of European ancestory. To characterise allelic effects on each disorder, we applied a multinomial logistic regression procedure with model selection to identify the best-fitting model of relations between genotype and phenotype. We examined cross-disorder effects of genome-wide significant loci previously identified for bipolar disorder and schizophrenia, and used polygenic risk-score analysis to examine such effects from a broader set of common variants. We undertook pathway analyses to establish the biological associations underlying genetic overlap for the five disorders. We used enrichment analysis of expression quantitative trait loci (eQTL) data to assess whether SNPs with cross-disorder association were enriched for regulatory SNPs in post-mortem brain-tissue samples. FINDINGS: SNPs at four loci surpassed the cutoff for genome-wide significance (p<5x10(-8)) in the primary analysis: regions on chromosomes 3p21 and 10q24, and SNPs within two L-type voltage-gated calcium channel subunits, CACNA1C and CACNB2. Model selection analysis supported effects of these loci for several disorders. Loci previously associated with bipolar disorder or schizophrenia had variable diagnostic specificity. Polygenic risk scores showed cross-disorder associations, notably between adult-onset disorders. Pathway analysis supported a role for calcium channel signalling genes for all five disorders. Finally, SNPs with evidence of cross-disorder association were enriched for brain eQTL markers. INTERPRETATION: Our findings show that specific SNPs are associated with a range of psychiatric disorders of childhood onset or adult onset. In particular, variation in calcium-channel activity genes seems to have pleiotropic effects on psychopathology. These results provide evidence relevant to the goal of moving beyond descriptive syndromes in psychiatry, and towards a nosology informed by disease cause. FUNDING: National Institute of Mental Health.BACKGROUND Findings from family and twin studies suggest that genetic contributions to psychiatric disorders do not in all cases map to present diagnostic categories. We aimed to identify specific variants underlying genetic effects shared between the five disorders in the Psychiatric Genomics Consortium: autism spectrum disorder, attention deficit-hyperactivity disorder, bipolar disorder, major depressive disorder, and schizophrenia. METHODS We analysed genome-wide single-nucleotide polymorphism (SNP) data for the five disorders in 33,332 cases and 27,888 controls of European ancestory. To characterise allelic effects on each disorder, we applied a multinomial logistic regression procedure with model selection to identify the best-fitting model of relations between genotype and phenotype. We examined cross-disorder effects of genome-wide significant loci previously identified for bipolar disorder and schizophrenia, and used polygenic risk-score analysis to examine such effects from a broader set of common variants. We undertook pathway analyses to establish the biological associations underlying genetic overlap for the five disorders. We used enrichment analysis of expression quantitative trait loci (eQTL) data to assess whether SNPs with cross-disorder association were enriched for regulatory SNPs in post-mortem brain-tissue samples. FINDINGS SNPs at four loci surpassed the cutoff for genome-wide significance (p<5×10(-8)) in the primary analysis: regions on chromosomes 3p21 and 10q24, and SNPs within two L-type voltage-gated calcium channel subunits, CACNA1C and CACNB2. Model selection analysis supported effects of these loci for several disorders. Loci previously associated with bipolar disorder or schizophrenia had variable diagnostic specificity. Polygenic risk scores showed cross-disorder associations, notably between adult-onset disorders. Pathway analysis supported a role for calcium channel signalling genes for all five disorders. Finally, SNPs with evidence of cross-disorder association were enriched for brain eQTL markers. INTERPRETATION Our findings show that specific SNPs are associated with a range of psychiatric disorders of childhood onset or adult onset. In particular, variation in calcium-channel activity genes seems to have pleiotropic effects on psychopathology. These results provide evidence relevant to the goal of moving beyond descriptive syndromes in psychiatry, and towards a nosology informed by disease cause. FUNDING National Institute of Mental Health.

Collaborative genome-wide association analysis supports a role for ANK3 and CACNA1C in bipolar disorder

To identify susceptibility loci for bipolar disorder, we tested 1.8 million variants in 4,387 cases and 6,209 controls and identified a region of strong association (rs10994336, P = 9.1 × 10−9) in ANK3 (ankyrin G). We also found further support for the previously reported CACNA1C (alpha 1C subunit of the L-type voltage-gated calcium channel; combined P = 7.0 × 10−8, rs1006737). Our results suggest that ion channelopathies may be involved in the pathogenesis of bipolar disorder.

Long-term implications of early onset in bipolar disorder: data from the first 1000 participants in the systematic treatment enhancement program for bipolar disorder (STEP-BD).

BACKGROUND Early onset of mood symptoms in bipolar disorder has been associated with poor outcome in many studies; however, the factors that might contribute to poor outcome have not been adequately investigated. METHODS The first consecutive 1000 adult bipolar patients enrolled in the National Institute of Mental Healths Systematic Treatment Enhancement Program for Bipolar Disorder were assessed at study entry to determine details of their age of onset of mood symptoms. Clinical course, comorbidity, and functional status and quality of life were compared for groups with very early (age < 13 years), early (age 13-18 years), and adult (age > 18 years) onset of mood symptoms. RESULTS Of 983 subjects in whom age of onset could be determined, 272 (27.7%) experienced very early onset, and 370 (37.6%) experienced early onset. Earlier onset was associated with greater rates of comorbid anxiety disorders and substance abuse, more recurrences, shorter periods of euthymia, greater likelihood of suicide attempts and violence, and greater likelihood of being in a mood episode at study entry. CONCLUSIONS Very early or early onset of bipolar disorder might herald a more severe disease course in terms of chronicity and comorbidity. Whether early intervention might modify this risk merits further investigation.

Whole-genome association study of bipolar disorder

We performed a genome-wide association scan in 1461 patients with bipolar (BP) 1 disorder, 2008 controls drawn from the Systematic Treatment Enhancement Program for Bipolar Disorder and the University College London sample collections with successful genotyping for 372 193 single nucleotide polymorphisms (SNPs). Our strongest single SNP results are found in myosin5B (MYO5B; P=1.66 × 10−7) and tetraspanin-8 (TSPAN8; P=6.11 × 10−7). Haplotype analysis further supported single SNP results highlighting MYO5B, TSPAN8 and the epidermal growth factor receptor (MYO5B; P=2.04 × 10−8, TSPAN8; P=7.57 × 10−7 and EGFR; P=8.36 × 10−8). For replication, we genotyped 304 SNPs in family-based NIMH samples (n=409 trios) and University of Edinburgh case–control samples (n=365 cases, 351 controls) that did not provide independent replication after correction for multiple testing. A comparison of our strongest associations with the genome-wide scan of 1868 patients with BP disorder and 2938 controls who completed the scan as part of the Wellcome Trust Case–Control Consortium indicates concordant signals for SNPs within the voltage-dependent calcium channel, L-type, alpha 1C subunit (CACNA1C) gene. Given the heritability of BP disorder, the lack of agreement between studies emphasizes that susceptibility alleles are likely to be modest in effect size and require even larger samples for detection.

Genome-wide association for major depressive disorder: a possible role for the presynaptic protein piccolo

Major depressive disorder (MDD) is a common complex trait with enormous public health significance. As part of the Genetic Association Information Network initiative of the US Foundation for the National Institutes of Health, we conducted a genome-wide association study of 435 291 single nucleotide polymorphisms (SNPs) genotyped in 1738 MDD cases and 1802 controls selected to be at low liability for MDD. Of the top 200, 11 signals localized to a 167 kb region overlapping the gene piccolo (PCLO, whose protein product localizes to the cytomatrix of the presynaptic active zone and is important in monoaminergic neurotransmission in the brain) with P-values of 7.7 × 10−7 for rs2715148 and 1.2 × 10−6 for rs2522833. We undertook replication of SNPs in this region in five independent samples (6079 MDD independent cases and 5893 controls) but no SNP exceeded the replication significance threshold when all replication samples were analyzed together. However, there was heterogeneity in the replication samples, and secondary analysis of the original sample with the sample of greatest similarity yielded P=6.4 × 10−8 for the nonsynonymous SNP rs2522833 that gives rise to a serine to alanine substitution near a C2 calcium-binding domain of the PCLO protein. With the integrated replication effort, we present a specific hypothesis for further studies.

The expert consensus guideline series

Abstract Over the past decade, many new epilepsy treatments have been approved in the United States, promising better quality of life for many with epilepsy. However, clinicians must now choose among a growing number of treatment options and possible combinations. Randomized clinical trials (RCTs) form the basis for evidence-based decision making about best treatment options, but they rarely compare active therapies, making decisions difficult. When medical literature is lacking, expert opinion is helpful, but may contain potential biases. The expert consensus method is a new approach for statistically analyzing pooled opinion to minimize biases inherent in other systems of summarizing expert opinion. We used this method to analyze expert opinion on treatment of three epilepsy syndromes (idiopathic generalized epilepsy, symptomatic localization-related epilepsy, and symptomatic generalized epilepsy) and status epilepticus. For all three syndromes, the experts recommended the same general treatment strategy. As a first step, they recommend monotherapy. If this fails, a second monotherapy should be tried. Following this, the experts are split between additional trials of monotherapy and a combination of two therapies. If this fails, most agree the next step should be additional trials of two therapies, with less agreement as to the next best step after this. One exception to these recommendations is that the experts recommend an evaluation for epilepsy surgery after the third failed step for symptomatic localization-related epilepsies. The results of the expert survey were used to develop user-friendly treatment guidelines concerning overall treatment strategies and choice of specific medications for different syndromes and for status epilepticus.

The International Society for Bipolar Disorders (ISBD) Task Force Report on Antidepressant Use in Bipolar Disorders

OBJECTIVE The risk-benefit profile of antidepressant medications in bipolar disorder is controversial. When conclusive evidence is lacking, expert consensus can guide treatment decisions. The International Society for Bipolar Disorders (ISBD) convened a task force to seek consensus recommendations on the use of antidepressants in bipolar disorders. METHOD An expert task force iteratively developed consensus through serial consensus-based revisions using the Delphi method. Initial survey items were based on systematic review of the literature. Subsequent surveys included new or reworded items and items that needed to be rerated. This process resulted in the final ISBD Task Force clinical recommendations on antidepressant use in bipolar disorder. RESULTS There is striking incongruity between the wide use of and the weak evidence base for the efficacy and safety of antidepressant drugs in bipolar disorder. Few well-designed, long-term trials of prophylactic benefits have been conducted, and there is insufficient evidence for treatment benefits with antidepressants combined with mood stabilizers. A major concern is the risk for mood switch to hypomania, mania, and mixed states. Integrating the evidence and the experience of the task force members, a consensus was reached on 12 statements on the use of antidepressants in bipolar disorder. CONCLUSIONS Because of limited data, the task force could not make broad statements endorsing antidepressant use but acknowledged that individual bipolar patients may benefit from antidepressants. Regarding safety, serotonin reuptake inhibitors and bupropion may have lower rates of manic switch than tricyclic and tetracyclic antidepressants and norepinephrine-serotonin reuptake inhibitors. The frequency and severity of antidepressant-associated mood elevations appear to be greater in bipolar I than bipolar II disorder. Hence, in bipolar I patients antidepressants should be prescribed only as an adjunct to mood-stabilizing medications.

Manic symptoms during depressive episodes in 1,380 patients with bipolar disorder: findings from the STEP-BD.

OBJECTIVE Little is known about how often bipolar depressive episodes are accompanied by subsyndromal manic symptoms in bipolar I and II disorders. The authors sought to determine the frequency and clinical correlates of manic symptoms during episodes of bipolar depression. METHOD From among 4,107 enrollees in the National Institute of Mental Healths Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD), 1,380 individuals met criteria for bipolar I or II depressive syndromes at the time of enrollment and were assessed for concomitant manic symptoms. Illness characteristics were compared in patients with pure bipolar depressed episodes and those with mixed depressive presentations. RESULTS Two-thirds of the subjects with bipolar depressed episodes had concomitant manic symptoms, most often distractibility, flight of ideas or racing thoughts, and psychomotor agitation. Patients with any mixed features were significantly more likely than those with pure bipolar depressed episodes to have early age at illness onset, rapid cycling in the past year, bipolar I subtype, history of suicide attempts, and more days in the preceding year with irritability or mood elevation. CONCLUSIONS Manic symptoms often accompany bipolar depressive episodes but may easily be overlooked when they appear less prominent than depressive features. Subsyndromal manic symptoms during bipolar I or II depression demarcate a more common, severe, and psychopathologically complex clinical state than pure bipolar depression and merit recognition as a distinct nosologic entity.

Antidepressant Use and Risk of Incident Cardiovascular Morbidity and Mortality Among Postmenopausal Women in the Women's Health Initiative Study

BACKGROUND Antidepressants are commonly prescribed medications, but their effect on cardiovascular morbidity and mortality remains unclear. METHODS Prospective cohort study of 136 293 community-dwelling postmenopausal women in the Womens Health Initiative (WHI). Women taking no antidepressants at study entry and who had at least 1 follow-up visit were included. Cardiovascular morbidity and all-cause mortality for women with new antidepressant use at follow-up (n = 5496) were compared with those characteristics for women taking no antidepressants at follow-up (mean follow-up, 5.9 years). RESULTS Antidepressant use was not associated with coronary heart disease (CHD). Selective serotonin reuptake inhibitor (SSRI) use was associated with increased stroke risk (hazard ratio [HR],1.45, [95% CI, 1.08-1.97]) and all-cause mortality (HR,1.32 [95% CI, 1.10-1.59]). Annualized rates per 1000 person-years of stroke with no antidepressant use and SSRI use were 2.99 and 4.16, respectively, and death rates were 7.79 and 12.77. Tricyclic antidepressant (TCA) use was associated with increased risk of all-cause mortality (HR,1.67 [95% CI, 1.33-2.09]; annualized rate, 14.14 deaths per 1000 person-years). There were no significant differences between SSRI and TCA use in risk of any outcomes. In analyses by stroke type, SSRI use was associated with incident hemorrhagic stroke (HR, 2.12 [95% CI, 1.10-4.07]) and fatal stroke (HR, 2.10 [95% CI, 1.15-3.81]). CONCLUSIONS In postmenopausal women, there were no significant differences between SSRI and TCA use in risk of CHD, stroke, or mortality. Antidepressants were not associated with risk of CHD. Tricyclic antidepressants and SSRIs may be associated with increased risk of mortality, and SSRIs with increased risk of hemorrhagic and fatal stroke, although absolute event risks are low. These findings must be weighed against quality of life and established risks of cardiovascular disease and mortality associated with untreated depression.