Role of genetic factors in human sexual behavior based on studies of Tourette syndrome and ADHD probands and their relatives

Distressing Problems with Sexual Function and Symptoms of Attention-Deficit/Hyperactivity Disorder

Cognitive models of sexual dysfunction situate distraction as a core mechanism underlying difficulties with sexual function. It follows that individuals who have difficulties with inattention and distractibility (e.g., attention-deficit/hyperactivity disorder; ADHD) may be at increased risk of problems with their sexual function, though previous research is mixed, and no research has examined links with sexual distress despite distress being a necessary criterion for sexual dysfunction. The goals of the current study were to: (1) examine associations between ADHD symptoms, sexual function, and sexual distress; (2) examine group differences in sexual function and sexual distress as a function of presumptive ADHD diagnosis; and (3) establish whether individuals with presumptive ADHD are at greater risk of distressing problems with sexual function relative to controls. In a large mixed-gender community sample (N = 943: controls n = 837, presumptive ADHD n = 106), we found that ADHD symptoms were positively correlated with worse overall sexual function, as well as orgasm difficulties and greater sexual distress. Relative to controls, individuals with presumptive ADHD reported worse sexual function and greater sexual distress, controlling for age, biological sex, and sexual orientation. Individuals with presumptive ADHD were significantly more likely (OR = 2.16) to have distressing problems with sexual function than controls. Core difficulties related to ADHD, including inattention, distractibility, and emotion dysregulation, may make individuals more vulnerable to experiencing problems with sexual function and sexual distress, putting them at risk for developing sexual dysfunction. Taken together, these data support associations between ADHD and distressing sexual function problems, including possible mechanisms explaining these links such as difficulties with emotion regulation.

Compulsive sexual behavior and paraphilic interests in adults with chronic tic disorders and Tourette syndrome: a survey-based study

Early research suggested that compulsive sexual behavior (CSB) and paraphilic interests (PI) are more prevalent in adults with primary tic disorders compared to the general population. However, recent data on this topic remain scarce. We conducted an anonymous online survey capturing data on CSB and PI in adult patients with primary tic disorders. We also explored the role of antipsychotic tic medication and the impact of neuropsychiatric comorbidities like attention-deficit hyperactivity disorder and depression. In total, 62 participants (26 females/36 males) completed the survey. The prevalence of CSB and PI were 12.9% and 19.4%, respectively. There was no association with antipsychotic medication nor with symptoms of depression. However, the presence of attention-deficit hyperactivity disorder was associated with a higher prevalence of both CSB and PI. The current results contrast with earlier reports and show that in adults with primary tic disorders, the prevalence of CSB and PI is not overly prominent.

Association of ADHD and hypersexuality and paraphilias

Subjects with ADHD suffer from inattention, hyperactivity, and impulsivity. Clinicians often assume that specific symptoms of ADHD are bound to affect sexual desire by increasing the frequency of hypersexuality. There is a lack of knowledge about the comorbidity between ADHD, hypersexuality, and paraphilias. The aim of this article was to provide a review of the literature on the association of ADHD and hypersexuality and paraphilias and to discuss the screening and the management of these syndromes when associated with ADHD. A systematic review of the literature was performed in PubMed, PsychInfo, and Embase databases. The studies reviewed show that some individuals who suffer from ADHD report hypersexuality and paraphilias, but no clear data emerged supporting the idea that hypersexuality and paraphilias are more frequent in an ADHD population. On the other hand, some studies showed a high prevalence of ADHD in hypersexual and paraphilic subjects. This is the first systematic review of hypersexuality and paraphilias in individuals with ADHD. However, the results are limited by differences in the methodology and measurement instruments for hypersexuality and paraphilias as well as by the small number of studies and the small sample sizes of many studies.

Sexual Function, Sexual Dysfunctions, and ADHD: A Systematic Literature Review

BACKGROUND

The scientific literature on sexuality among mentally ill patients clearly shows a higher prevalence of sexual disorders for many mental disorders, but little is known about sexuality in individuals suffering from ADHD. Clinicians will often assume that specific difficulties of ADHD are bound to affect sexual functioning.

AIM

The aim of this study was to provide a review of the literature to gain better knowledge about sexuality in subjects with ADHD and to discuss screening and management of their potential sexual problems.

METHODS

A systematic review of the literature was performed in Pubmed, PsychInfo, and Embase databases.

MAIN OUTCOME MEASURES

The main outcome measures were sexual function and sexual dysfunctions.

RESULTS

The studies indicated that subjects with ADHD report more sexual desire, more masturbation frequency, less sexual satisfaction, and more sexual dysfunctions than the general population.

CLINICAL IMPLICATIONS

Clinicians working with subjects with ADHD should explore the quality of their sexual life.

STRENGTHS & LIMITATIONS

This is the first systematic review of the sexuality of individuals with ADHD. However, the results are limited by the small number of studies, by the small sample size of many studies, and the potential for bias.

CONCLUSIONS

ADHD is a mental disorder affecting sexual health. Further studies are warranted to learn more about sexuality in subjects with ADHD. Soldati L, Bianchi-Demicheli F, Schockaert P, et al. Sexual Function, Sexual Dysfunctions, and ADHD: A Systematic Literature Review. J Sex Med 2020;17:1653-1664.

Clinical Features That Evoke the Concept of Disinhibition in Tourette Syndrome

The capacity to efficiently control motor output, by either refraining from prepotent actions or disengaging from ongoing motor behaviors, is necessary for our ability to thrive in a stimulus-rich and socially complex environment. Failure to engage in successful inhibitory motor control could lead to aberrant behaviors typified by an excess of motor performance. In tic disorders and Tourette syndrome (TS) - the most common tic disorder encountered in clinics - surplus motor output is rarely the only relevant clinical sign. A range of abnormal behaviors is often encountered which are historically viewed as "disinhibition phenomena". Here, we present the different clinical features of TS from distinct categorical domains (motor, sensory, complex behavioral) that evoke the concept of disinhibition and discuss their associations. We also present evidence for their consideration as phenomena of inhibitory dysfunction and provide an overview of studies on TS pathophysiology which support this view. We then critically dissect the concept of disinhibition in TS and illuminate other salient aspects, which should be considered in a unitary pathophysiological approach. We briefly touch upon the dangers of oversimplification and emphasize the necessity of conceptual diversity in the scientific exploration of TS, from disinhibition and beyond.

Masochism and pathological gambling

That all pathological gamblers have an "unconscious wish to lose," an idea first expressed by Freud and Bergler, is neither true nor useful; wrong as well, however, are the reasons for neglecting masochism in relation to gambling. There is a small but clinically significant subgroup of pathological gamblers who are masochistic. I present clinical vignettes and a more extended treatment account to illustrate its importance. Masochism has been a confusing concept. As used here it refers to the deliberate seeking of pain, loss, suffering, or humiliation. There may be pleasure in pain, or an obligatory combining of pleasure and pain. A sense of power and control may be achieved through suffering. The case material illustrates clinically useful types (sexual masochism, masochistic personality disorder, moral masochism, relational masochism) as well as some common masochistic dynamics encountered in the treatment of pathological gamblers. These masochistic patterns are often identifiable during the initial evaluation. Distinguishing features may include a reversal of normal attitudes about winning and losing, the absence of an early winning phase, sometimes a memorable early loss. Gamblers may sabotage opportunities for success or create unnecessary obstacles for themselves. Losing may be more comfortable than winning or may be overtly sexualized.

Potential implications of research on genetic or heritable contributions to pedophilia for the objectives of criminal law

In recent years, there has been increasing scientific research on possible genetic or heritable influences to the etiology of pedophilia, driven by national and public concerns about better understanding the disorder in order to reduce children's vulnerabilities to pedophilic and child sex offenders. This research has corresponded to growing academic dialogue on how advances in genetic research, especially concerning the causes and development of particular mental disorders or behaviors, may affect traditional practices of criminal law and how the justice system views, manages, and adjudicates different types of criminal behavior and offenders. This paper strives to supplement this dialogue by exploring several of the many possible effects and implications of research surrounding genetic or heritable contributions to pedophilia for the five widely accepted objectives that enforce and regulate the punishment of criminal law. These include retribution, incapacitation, deterrence, rehabilitation, and restoration. Although still currently in early stages, genetic and heritability research on the etiology of pedophilia may have the potential moving forward to influence the current and established punitive methods and strategies of how the justice system perceives, adjudicates, regulates, and punishes pedophilic and sex offenders, as well as how to best prevent sexual offending against children by pedophilic offenders in the future.

Hypothesizing repetitive paraphilia behavior of a medication refractive Tourette's syndrome patient having rapid clinical attenuation with KB220Z-nutrigenomic amino-acid therapy (NAAT)

Background and aims Many patients presenting multiple behaviors including drug and food abuse as well as other pathological repetitive unwanted activities such as gambling, self-mutilation and paraphilias may not be appropriately diagnosed. Here we present a case of a male presenting many of these seemingly diverse behaviors and finally diagnosed with reward deficiency syndrome (RDS) by his attending physician. Methods The use of the dopamine agonist, ropinirole after two weeks showed improvement in terms of sexual behavior but tolerance set in and was discontinued especially when an infraction occurred with the patient's insurance. In this article, we carefully explore the potential of ropinirole to downregulate dopamine receptors causing adenylate cyclase receptor supersensitivity and tolerance a feature of neurotransmitter cross-talk. Based on previous scientific evidence showing KB220Znutrigenomic amino-acid therapy (NAAT) to rapidly (post one-hour) activate dopaminergic pathways in both the pre-frontal cortex cingulate gyrus (relapse loci) and ventral tegmental area-caudate-accumbens-putamen (craving and emotion loci) the patient was prescribed NAAT. Results and discussion Within one week of utilization the repetitive paraphilia was eliminated. There were also a number of other positive effects such as enhanced focus that persisted even after the patient stopped using KB220Z suggesting neuroplasticity (e.g. altruistic thoughts). However, these observed profound benefits require more in-depth study, especially in a large cohort against a placebo. While this report focused on a rapid response rather than long-term benefits previously associated with NAAT, it is somewhat encouraging and longer term required follow-up and larger placebo controlled studies are warranted before any definitive conclusions could be gleaned from this case report.

Pedophilia: neuropsychological evidence encouraging a brain network perspective

Although the vast majority of current pathogenetic theories support a neurobiological understanding of psychiatric disorders, the brain functional correlates of pedophilia are largely unknown. Based on prior behavior genetics research on human sexual orientation and phenomenology as well as the phenotypical intersection of pedophilia with other psychiatric spectrum disorders, we hypothesize the involvement of striato-thalamo-cortical processing loops in the formation of pedophilic urges and behaviors. Data from a current neuropsychological pilot study in four pedophiles encourage our brain functional perspective. As deduced from the network model, all four patients exhibited pronounced and circumscribed deficits in cognitive domains mediated by striato-thalamically controlled areas of the frontal cortex. All patients were especially impaired in neuropsychological functions associated with the prefrontal and motor processing loops (e.g., response inhibition, working memory and cognitive flexibility), with a performance level located up to five standard deviations below the normative data. Contrary to this, neuropsychological performances in cognitive domains without a comparable high frontal loading were in all participants unobtrusive. In future, studying gene by environment interactions in combination with functional neuroimaging and neuropsychological assessment is promising to elucidate the pathophysiological relationship of psychiatric disorders that are characterized by inadequate urges and poor behavioral inhibition.

Psychiatric disorders and recidivism in sexual offenders

Research on psychiatric morbidity in sexual offenders (SOs) has mostly been based on small, selected samples. We studied psychiatric disorders and their relationship with criminal recidivism in a nationwide, representative cohort of SOs. Data on ICD-9 and -10 psychiatric and neurologic morbidity diagnosed during hospital admissions 1987-1997, but prior to sexual offending, were retrieved for all adult male SOs released from Swedish prisons 1993-1997 (N = 1215). Preoffending disorder prevalence and associations between morbidity and criminal reconvictions during a 5-year postdetainment follow-up were explored. Alcohol use disorder was the most frequent diagnosis, followed by drug use disorder, personality disorder, and psychosis. Morbidity requiring admission to hospital was more common in rapists as compared to child molesters. Alcohol use disorder, drug use disorder, personality disorder, and psychosis all increased the risk for sexual recidivism whereas alcohol use disorder and personality disorder predicted violent nonsexual recidivism. Controlling for sociodemographic confounds changed the risk estimates only marginally. Because disorders were identified among only those who had been admitted to psychiatric hospitals as inpatients, underestimation of true prevalence rates was inevitable. However, our findings support psychiatric consultation for improved assessment and management of mental health needs and recidivism risk in SOs.

Sexual differentiation of the brain: genes, estrogen, and neurotrophic factors

Based on evidence obtained during the past 50 years, the current hypothesis to explain the sexual dimorphism of structure and function in the brain of vertebrates maintains that these differences are produced by the epigenetic action of gonadal hormones. However, evidence has progressively accumulated suggesting that genetic mechanisms controlling sexual-specific neuronal characteristics precede, or occur in parallel with, hormonal effects. 1. In cultures of hypothalamic neurons taken from gestation day 16 (GD16) embryos, treatment of sexually segregated cultures with estradiol (E2) induces axon growth in neurons from male neurons, but not from female neurons. In these cultures treatment with E2 increased the levels of tyrosine kinase type B (TrkB) and insulin-like growth factor I (IGF-I) receptors in male but not in female neurons. This and other sex differences cannot be explained by differences in hormonal environment, because the donor embryos were obtained when gonadal secretion of steroids is just beginning, before the perinatal surge of testosterone that determines development of the male brain beginning at GD17/18. 2. The response to estrogen is contingent upon coculture with heterotopic glia (mostly astrocytes) from a target region (amygdala) harvested from same-sex fetuses at GD16, whereas in the presence of homotopic glia or in cultures without glia, E2 had no effect. It was concluded that the axogenic effect of E2 depends on interaction between neurons and glia from a target region and that neurons from fetal male donors appear to mature earlier than neurons from females, a differentiated response that takes place prior to divergent exposure to gonadal secretions. 3. The effects of target and nontarget glia-conditioned media (CM) on the E2-induced growth of neuronal processes of hypothalamic neurons obtained from sexually segregated fetal donors were also studied. Estrogen added to media conditioned by target glia modified the number of primary neurites and the growth of axons of hypothalamic neurons of males but not of females. 4. Neither the Type III steroidal receptor blocker tamoxifen nor Type I antiestrogen ICI 182,780 prevented the axogenic effects of the hormone. Estradiol made membrane-impermeable by conjugation to a protein of high molecular weight (E2-BSA) preserved its axogenic capacity, suggesting the possibility of a membrane effect responsible for the action of E2. 5. Western blot analysis of the tyrosine kinase type A (TrkA), type B (TrkB), type C (TrkC), and insulin-like growth factor (IGF-I R) receptors in extracts from homogenates of cultured hypothalamic neurons showed that in cultures of male-derived neurons grown with E2 and CM from target glia, the amounts of TrkB and IGF-I R increased notably. Densitometric quantification showed that these cultures had more TrkB than cultures with CM alone or E2 alone. On the contrary, in cultures of female-derived neurons, the presence of CM alone induced maximal levels of TrkB, which were not further increased by E2; female-derived neurons in all conditions did not contain IGF-I R. Levels of TrkC were not modified by any experimental condition in male- or female-derived cultures and Trk A was not found in the homogenates. These results are compared with similar data from other laboratories and integrated in a model for the confluent interaction of estrogen and neurotrophic factors released by glia that may contribute to the sexual differentiation of the brain.

The central role of magnesium deficiency in Tourette's syndrome: causal relationships between magnesium deficiency, altered biochemical pathways and symptoms relating to Tourette's syndrome and several reported comorbid conditions

Prior studies have suggested a common etiology involved in Tourette's syndrome and several comorbid conditions and symptomatology. Reportedly, current medications used in Tourette's syndrome have intolerable side-effects or are ineffective for many patients. After thoroughly researching the literature, I hypothesize that magnesium deficiency may be the central precipitating event and common pathway for the subsequent biochemical effects on substance P, kynurenine, NMDA receptors, and vitamin B6 that may result in the symptomatology of Tourette's syndrome and several reported comorbid conditions. These comorbid conditions and symptomatology include allergy, asthma, autism, attention deficit hyperactivity disorder, obsessive compulsive disorder, coprolalia, copropraxia, anxiety, depression, restless leg syndrome, migraine, self-injurious behavior, autoimmunity, rage, bruxism, seizure, heart arrhythmia, heightened sensitivity to sensory stimuli, and an exaggerated startle response. Common possible environmental and genetic factors are discussed, as well as biochemical mechanisms. Clinical studies to determine the medical efficacy for a comprehensive magnesium treatment option for Tourette's syndrome need to be conducted to make this relatively safe, low side-effect treatment option available to doctors and their patients.

The paraphilic and hypersexual disorders: an overview

In this article, the first of a two-part series, the authors present reasons for considering the paraphilic and hypersexual disorders together and provide an overview of these disorders. The DSM-IV diagnostic criteria for paraphilias are reviewed, and proposed criteria for hypersexual disorders are presented. The question of whether the paraphilic and hypersexual disorders should be considered within the spectrum of obsessive-compulsive disorders is considered. The authors then review the epidemiology of these disorders, and discuss some implications of recent sexual predator legislation. The authors discuss the etiology of the paraphilias and hypersexual disorders, and consider the role of endocrinological function, findings from brain imaging and neuropsychological testing, findings from primate research, the monoamine hypothesis, the imprinting hypothesis, social learning theory, the concept of courtship disorder, the role of obsessive-compulsive elements, psychodynamic theories, and genetic factors. The phenomenology of the paraphilias and hypersexual disorders is discussed, including the tendency for multiple paraphilias to co-occur, the lack of a specific offender profile, the predominance of males among those with paraphilias, the incidence of a history of victimization in individuals with paraphilias and compulsive sexual disorders, the onset and course of both types of disorders, and the lack of internal motivation for change in individuals with paraphilias and hypersexual disorders. The authors then discuss disorders that commonly co-occur with paraphilias and compulsive sexual disorders, including mood disorders, substance abuse and dependence disorders, attention-deficit/hyperactivity disorder, anxiety and impulse control disorders, and personality disorders. The second article in the series will discuss the clinical assessment and the behavioral and psychopharmacological treatment of these disorders. A guide for clinicians and patients on where and how to find specialized clinicians and treatment resources in the United States will also be provided.

Clinical and molecular genetics of ADHD and Tourette syndrome. Two related polygenic disorders

ADHD is a polygenic disorder due to the additive effect of genes affecting dopamine, norepinephrine, serotonin, GABA, and other neurotransmitters. Some of the specific loci involved are dopamine genes--DRD2, DRD4, DRD5, and the dopamine transporter; norepinephrine (NE) and epinephrine (EPI) genes--dopamine beta-hydroxylase, ADRA2A, ADRA2C, PNMT, norepinephrine transporter, MAOA, COMT; serotonin genes--TDO2, HTR1A, HTR1DA, serotonin transporter; GABA genes--GABRB3; androgen receptor and other genes. This model is consistent with all of the present knowledge about ADHD including (a) the increased frequency of ADHD in the relatives of ADHD probands, (b) the presence of a wide spectrum of comorbid behaviors (depression, anxiety, learning, conduct, oppositional-defiant, conduct and substance abuse disorders) in ADHD probands and their relatives on both parental sides, (c) the close relationship to Tourette syndrome (TS), (d) the failure to find the genes for TS using linkage analysis, (e) the brain imaging studies showing hypometabolism of the frontal lobes, (f) the relationship between dopamine D2 receptor density and regional blood flow, (g) the correlation between tics and dopamine D2 receptor density in TS, (h) the motor hyperactivity of dopamine transporter and dopamine D3 receptor gene knockout mice, (i) the LeMoal and Shaywitz dopamine deficiency animal models of ADHD, (j) the NE models of ADHD, (k) the failure to explain ADHD on the basis of any single neurotransmitter defect, (l) the response of ADHD to dopamine and alpha 2-adrenergic agonists, (m) the small percentage of the variance of specific behaviors accounted for by each gene, and numerous other aspects of ADHD. The implications of the polygenic model for the understanding, diagnosis and treatment of ADHD and TS, as well as other psychiatric disorders, are reviewed.

Neuropsychiatry of hypersexuality

Relatively few studies of the psychobiology of hypersexuality have been undertaken. Nevertheless, the literature does suggest the possibility of a neurobiology of hypersexuality. Three cases of hypersexual behavior are presented in the context of neuropsychiatric disorders, and the literature on this phenomenon is briefly reviewed. These case studies and the literature provide evidence that different brain systems may play a role in this disorder. Frontal lesions may be accompanied by disinhibition, including impulsive hypersexual response to external cues, while striatal lesions may be accompanied by repetitive triggering of internally generated response patterns. Temporal-limbic lesions may be accompanied by disturbances in sexual appetite itself, including change in the direction of sexual drive. These case studies demonstrate that a neurobiology of hypersexuality may prove of some heuristic value in the clinic. However, further research is required to consolidate the literature in this area.

Psychopharmacologic treatments for nonparaphilic compulsive sexual behaviors

This article reviews the use of pharmacologic agents to treat nonparaphilic compulsive sexual behaviors (paraphilia-related disorders). Recent data suggest that serotonergic antidepressants, especially serotonin reuptake inhibitors (SRIs), may be effective in treating nonparaphilic sexual behaviors characterized by hypersexuality. The rationale, prescriptive use, and limitations of SRIs are reviewed, as are the proposed mechanisms of action, prescriptive use, and side effects of medications that lower serum testosterone (including triptorelin and the antiandrogens medroxyprogesterone acetate and cyproterone acetate).The potential use of psychostimulants, mood stabilizers, and atypical antipsychotics for paraphilia-related disorders in specific clinical situations is discussed. Practical guidelines, augmentation strategies with adjunctive psychopharmacologic agents, and indications regarding pharmacologic combinations of the above medications are suggested.

Attention deficit hyperactivity disorder in the presence of Tourette syndrome

Increasing attention to comorbidity in Tourette syndrome has led to a search for factors that would help in the development of treatment strategies for attention deficit hyperactivity disorder. Despite arguments and some research supporting various viewpoints, it is still unclear to what extent the frequency of co-occurrence is high in Tourette syndrome. It also is unclear whether attention deficit hyperactivity disorder and obsessive-compulsive disorder are part of a spectrum with related genetic or environmental factors. One of the main difficulties is obtaining a truly representative community sample and agreeing upon the categorical boundaries. The consequences of this argument are discussed. Effective treatment of attention deficit hyperactivity disorder in the presence of tics and Tourette syndrome has undergone considerable change from an absolute contraindication of stimulants to cautious use. For those whom stimulants fail or produce unacceptable side effects, nonstimulant medications are available in increasing variety. Much more methodologically adequate research needs to be undertaken with them.

Attention deficit hyperactivity disorder: an evolutionary perspective

Attention deficit hyperactivity disorder (ADHD) affects a significant portion of the population--some 5% of all school-aged children--and approximately half of these individuals continue to show the full disorder in adulthood. Recent studies point to a strong genetic component in the etiology of this disorder. Questions have been raised as to the relatively high prevalence of this condition in the population, given its apparent maladaptive nature in present-day society. In this article, we review and discuss three theories regarding the possible adaptive function of ADHD: the hunter, fighter, and wader theories. Although no theory entirely explains the occurrence of ADHD, it is worthwhile to note that, at least historically, ADHD may have served an adaptive function and may have been selected by the environment for survival.

Studies of the c-Harvey-Ras gene in psychiatric disorders

Hérault et al. (1993) previously reported a significant association between autism and the larger fragments of the c-Harvey-Ras (HRAS) Bam H1 polymorphism. We have sought to verify this finding and determine if there was any evidence for an association with other psychiatric disorders. Because of its greater sensitivity, we have examined the HRAS Msp 1 polymorphism. We found a just significant increase in the prevalence of the > 2.1 kb alleles in 48 subjects with autism versus 50 control subjects. There was no increase in the prevalence of the > 2.1 kb alleles in 164 probands with Tourette's syndrome. Examination of 16 preselected symptom clusters, however, showed a significant trend toward higher scores for obsessive-compulsive and phobic symptoms in > 2.1 kb homozygotes. While this locus requires further study, in conjunction with the results of Hérault et al., the present findings suggest that genetic defects in HRAS, and possibly other components of the G protein secondary messenger system, may play a role in some psychiatric disorders.

Polygenic inheritance of Tourette syndrome, stuttering, attention deficit hyperactivity, conduct, and oppositional defiant disorder: the additive and subtractive effect of the three dopaminergic genes--DRD2, D beta H, and DAT1

Polymorphisms of three different dopaminergic genes, dopamine D2 receptor (DRD2), dopamine beta-hydroxylase (D beta H), and dopamine transporter (DAT1), were examined in Tourette syndrome (TS) probands, their relatives, and controls. Each gene individually showed a significant correlation with various behavioral variables in these subjects. The additive and substractive effects of the three genes were examined by genotyping all three genes in the same set of subjects. For 9 of 20 TS associated comorbid behaviors there was a significant linear association between the degree of loading for markers of three genes and the mean behavior scores. The behavior variables showing the significant associations were, in order attention deficit hyperactivity disorder (ADHD), stuttering oppositional defiant, tics, conduct, obsessive-compulsive, mania, alcohol abuse and general anxiety-behaviors that constitute the most overt clinical aspects of TS. For 16 of the 20 behavior scores there was a linear progressive decrease in the mean score with progressively lesser loading for the three gene markers. These results suggest that TS, ADHD, stuttering oppositional defiant and conduct disorder, and other behaviors associated with TS, are polygenic, due in part to these three dopaminergic genes, and that the genetics of other polygenic psychiatric disorders may be deciphered using this technique.

Increased expression of aphidicolin-induced common fragile sites in Tourette syndrome: the key to understand the genetics of comorbid phenotypes?

In a comparison of 80 common aphidicolin-induced fragile sites (FS) between 26 DSM-IV Tourette syndrome (TS) and 24 control individuals, the mean of the summed break frequencies following mild aphidicolin pretreatment was significantly higher in TS individuals than in controls (P < 0.001). Other breakpoints encountered during this study, i.e., random breaks, breaks corresponding to rare FS, and breakpoints recorded by others but not listed as common FS according to the Chromosome Coordinating Meeting [1992] were listed as category II breakpoints. By using the most significantly different mean FS breakage figures between TS and control individuals, further stepwise discriminant analysis allowed identification of TS individuals from only a few sites in both the common FS and category II breakpoint groups. Future research needs to focus on confirmation of altered common fragile site expression in association with behavioral variation, whether expression of certain discriminatory sites concurs with specific comorbid disorder expression; the nature of the molecular alterations at these FS and the implications of a genomic instability phenotype for the mapping of a primary TS gene or genes.

Role of genetic factors in depression based on studies of Tourette syndrome and ADHD probands and their relatives

Tourette syndrome (TS) is a common, neuropsychiatric disorder which has many similarities to attention deficit hyperactivity disorder (ADHD). TS probands have a high frequency of a variety of behavioral disorders including depression. The depression may be due to a pleiotrophic effect of the Gts genes, proband ascertainment bias, or a result of coping with the chronic tics. To distinguish between these hypotheses we examined the responses to 17 Diagnostic Interview Schedule questions to evaluate the 9 DSM-III-R criteria for major depressive episode in 1,080 adults consisting of TS and ADHD probands, their relatives and controls. Using a Bonferonni corrected p there was a significant progressive increase in 16 of 17 depressive symptoms and for a life time history of a major depressive episode in groups with increased genetic loading for Gts genes. Similar trends were seen in the small number of ADHD probands and their relatives. There was also a significant increase for these variables in non-proband TS relatives versus non-TS relatives, indicating the association of depression with Gts genes was not due to ascertainment bias or the inappropriate choice of controls. Multiple linear regression analysis indicated that obsessive-compulsive behaviors, sex, ADHD, drug abuse, and age all showed a more significant effect on depressive symptoms than the number of tics. The presence or absence of TS in the relatives had a much greater effect on risk for depression than the presence or absence of an episode of major depression in the proband. These results are consistent with the hypothesis that Gts and ADHD genes play a major role in depression.

Genetic factors in substance abuse based on studies of Tourette syndrome and ADHD probands and relatives. I. Drug abuse

There have been relatively few studies of genetic factors in drug abuse. Childhood Attention Deficit Hyperactivity Disorder (ADHD) has been implicated as a risk factor, and pedigree studies of Tourette Syndrome (TS), a hereditary impulse disorder closely related to ADHD, show an increased prevalence of substance abuse in relatives. These observations suggest the genes for TS and ADHD may play an important role in the development of drug abuse. To examine this hypothesis 217 TS probands and 328 of their relatives, 58 ADHD probands and 35 of their relatives, and 50 controls were prospectively studied using a structured questionnaire based on the Diagnostic Interview Schedule. All subjects were Caucasians 16 to 49 years of age. The responses concerning the use of 8 different drugs and 8 different symptoms of drug abuse were compared. The results showed a highly significant increase in positive responses with increased loading for the TS and ADHD genes for 6 of the 8 drugs and all of the drug abuse symptoms. The percentage of positive responses in TS probands was markedly influenced by the presence of comorbid ADHD, as well as discipline, obsessive-compulsive, or alcohol problems. These results suggest that the genes responsible for TS and ADHD play an important role in drug abuse/dependence. The dopamine D2 receptor gene (DRD2) appears to be one of these genes since variants at this locus are significantly increased in frequency in TS, ADHD, conduct disorder and drug abuse.