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    Ada Johansson

    Naturalistic studies of gene-environment interactions (G X E) have been plagued by several limitations, including difficulty isolating specific environmental risk factors from other correlated aspects of the environment, gene-environment... more
    Naturalistic studies of gene-environment interactions (G X E) have been plagued by several limitations, including difficulty isolating specific environmental risk factors from other correlated aspects of the environment, gene-environment correlation (rGE ), and the use of a single genetic variant to represent the influence of a gene. We present results from 235 Finnish young men in two lab studies of aggression and alcohol challenge that attempt to redress these limitations of the extant G X E literature. Specifically, we use a latent variable modeling approach in an attempt to more fully account for genetic variation across the oxytocin receptor gene (OXTR) and to robustly test its main effects on aggression and its interaction with alcohol exposure. We also modeled aggression as a latent variable comprising various indices, including the average and maximum levels of aggression, the earliest trial on which aggression was expressed, and the proportion of trials on which the minimum...
    The multifaceted gut-brain peptide ghrelin and its receptor (GHSR-1a) are implicated in mechanisms regulating not only the energy balance but also the reward circuitry. In our pre-clinical models, we have shown that ghrelin increases... more
    The multifaceted gut-brain peptide ghrelin and its receptor (GHSR-1a) are implicated in mechanisms regulating not only the energy balance but also the reward circuitry. In our pre-clinical models, we have shown that ghrelin increases whereas GHSR-1a antagonists decrease alcohol consumption and the motivation to consume alcohol in rodents. Moreover, ghrelin signaling is required for the rewarding properties of addictive drugs including alcohol and nicotine in rodents. Given the hereditary component underlying addictive behaviors and disorders, we sought to investigate whether single nucleotide polymorphisms (SNPs) located in the pre-proghrelin gene (GHRL) and GHSR-1a gene (GHSR) are associated with alcohol use, measured by the alcohol use disorders identification test (AUDIT) and smoking. Two SNPs located in GHRL, rs4684677 (Gln90Leu) and rs696217 (Leu72Met), and one in GHSR, rs2948694, were genotyped in a subset (n = 4161) of a Finnish population-based cohort, the Genetics of Sexual...
    Recently, testosterone (T) has been shown to be associated with premature ejaculation (PE) symptoms in the literature. Furthermore, studies suggest that the etiology of PE is partly under genetic control. The aim of this study was to... more
    Recently, testosterone (T) has been shown to be associated with premature ejaculation (PE) symptoms in the literature. Furthermore, studies suggest that the etiology of PE is partly under genetic control. The aim of this study was to reassess findings suggesting an association between testosterone (T) and a key symptom of PE, ejaculation latency time (ELT), as well as exploratively investigating associations between six androgen-related genetic polymorphisms and ELT. Statistical analyses were performed on a population-based sample of 1,429 Finnish men aged 18-45 years (M = 26.9, SD = 4.7). Genotype information was available for 1,345-1,429 of these (depending on the polymorphism), and salivary T samples were available from 384 men. Two androgen receptor gene-linked, two 5-alpha-reductase type 2-gene-linked, and two sex hormone-binding globuline gene-linked polymorphisms were genotyped. Ejaculatory function was assessed using self-reported ELT. We found no association between salivar...
    Introduction.  Recently, attempts to formulate valid and suitable definitions for (different subcategories of) premature ejaculation have resulted in substantial progress in the pursuit to gain knowledge about ejaculatory function.... more
    Introduction.  Recently, attempts to formulate valid and suitable definitions for (different subcategories of) premature ejaculation have resulted in substantial progress in the pursuit to gain knowledge about ejaculatory function. However, the association between ejaculatory dysfunction and different types of sexual activities has yet to be thoroughly investigated, and (due to conflicting results between studies) the potential effects of age and relationship length still need to be taken into account.Aim.  The aim of this study is to investigate the associations of age, relationship length, frequency of different sexual activities, and different modes of achieving ejaculation with self-reported ejaculation latency time.Main Outcome Measures.  The main outcome is establishing associations between age, relationship length, self-reported ejaculation latency time, and frequency of different kinds of sexual activities and different modes of achieving ejaculation (such as achieving ejaculation through oral or vaginal sex).Methods.  Statistical analyses of data on age, relationship length, self-reported ejaculation latency time, and frequency of different sexual activities and different modes of achieving ejaculation were conducted on a population-based sample of 3,189 males aged 18–48 years (mean = 29.9 years, standard deviation = 6.94).Results.  Age and relationship length were significantly negatively associated with self-reported ejaculation latency time. Frequency of different kinds of sexual behavior generally had a positive association with self-reported ejaculation latency time, as had different modes of achieving ejaculation.Conclusions.  The findings highlight the need for more extensive studies on and increased knowledge of different aspects of ejaculatory function before a valid and suitable definition for premature ejaculation can be formulated. Jern P, Santtila P, Johansson A, Varjonen M, Witting K, von der Pahlen B, and Sandnabba K. Subjectively measured ejaculation latency time and its association with different sexual activities while controlling for age and relationship length. J Sex Med 2009;6:2568–2578.
    Introduction.  Recently, in anticipation of the Diagnostic and Statistical Manual of Mental Disorders V, much consideration has been given to the diagnostic criteria for premature ejaculation (PE). The scientific community is yet to agree... more
    Introduction.  Recently, in anticipation of the Diagnostic and Statistical Manual of Mental Disorders V, much consideration has been given to the diagnostic criteria for premature ejaculation (PE). The scientific community is yet to agree not only on the etiology of PE, but also on the most suitable diagnosis and forms of treatment. It has been suggested that the diagnostic criteria of PE should be strictly empirical and rely on intravaginal latency time alone, whereas others stress the need to also include psychological and personal factors.Aim.  To examine different indicators of PE and their relationship with and ability to predict sexual distress.Main Outcome Measures.  Statistical analyses of data on sexual distress and different measures of ejaculatory function on a population-based sample of 3,332 Finnish men.Methods.  The present study involved a population-based sample of 3,332 males, of which 2,328 were twins aged 18–33, and 1,004 were over 18-year-old siblings to the aforementioned (M = 26.17 years of age). The individual contributions of different PE-indicator variables to experienced sexual distress were investigated by calculating correlations and performing a regression analysis.Results.  All included indicators of PE were significantly associated with sexual distress, and significant and logical differences in sexual distress were found between intravariable levels for several of the indicator variables. Only variables relating to subjective experience (e.g., worrying about PE) were uniquely related to sexual distress when other indicators were controlled for.Conclusions.  The results suggest that variables measuring subjective experience may be useful when considering diagnostic criteria if indicators that are related to sexual distress are considered useful. However, overall, the association between PE and sexual distress is not especially strong, emphasizing the fact that more objective indicators of PE may not necessarily be associated with significant distress. Jern P, Santtila P, Johansson A, Varjonen M, Witting K, Ålgars M, Alanko K, von der Pahlen B, and Sandnabba K. Indicators of premature ejaculation and their associations with sexual distress in a population-based sample of young twins and their siblings. J Sex Med 2008;5:2191–2201.
    Introduction.  A number of different theoretical approaches to understanding the etiology of ejaculatory dysfunction have been proposed, but no behavior genetic study has yet, to our knowledge, been conducted to explore the genetic and... more
    Introduction.  A number of different theoretical approaches to understanding the etiology of ejaculatory dysfunction have been proposed, but no behavior genetic study has yet, to our knowledge, been conducted to explore the genetic and environmental influences on ejaculatory dysfunction.Aim.  The aim of the present study was to explore the genetic and environmental effects on premature (PE) and delayed (DE) ejaculation in a population-based sample.Methods.  The genetic and environmental influences on PE and DE were investigated in a population-based sample of 1,196 Finnish male twins, age 33–43 years, with 91 identical and 110 complete twin pairs. Several different aspects of ejaculatory function were measured by a self-report questionnaire (e.g., latency time, subjective experience of ejaculatory control). Factor analyses distinguished two subcomponents of ejaculatory function, and subsequently, composite variables measuring PE and DE were created. Structural equation modeling was performed on the composite variables.Main Outcome Measures.  Measurement of genetic and environmental effects on PE and DE.Results.  The results suggested moderate genetic influence (28%) on PE, but not on DE (0%). There was a moderate familial effect on DE with shared environmental effects accounting for 24% of the variance. However, omission of the shared environmental component did not directly result in a significantly decreased model fit for DE, and omission of the additive genetic component did not directly result in a significantly decreased fit for the PE model.Conclusions.  The findings from the present study provide useful information regarding the etiology and understanding of ejaculatory dysfunction. Jern P, Santtila P, Witting K, Alanko K, Harlaar N, Johansson A, von der Pahlen B, Varjonen M, Vikström N, Ålgars M, and Sandnabba K. Premature and delayed ejaculation: Genetic and environmental effects in a population-based sample of Finnish twins. J Sex Med 2007;4:1739–1749.
    The Sexual Inhibition and Sexual Excitation Scales (SIS/SES) measure the propensity for sexual inhibition and excitation in men. According to the theoretical model underlying the SIS/SES, sexual response and associated behavior depend on... more
    The Sexual Inhibition and Sexual Excitation Scales (SIS/SES) measure the propensity for sexual inhibition and excitation in men. According to the theoretical model underlying the SIS/SES, sexual response and associated behavior depend on dual control mechanisms in the brain involving the balance of excitatory and inhibitory systems which impinge on sexual response. Previous research with the SIS/SES has indicated one higher-order excitatory factor and two higher-order inhibitory factors affecting sexual response. The present study analyzed the item structure and the psychometric properties of the instrument in a population based sample of Finnish male twins (N = 1,289), and, including 37 out of 45 items of the original scales, estimated the heritability of and the environmental influences on the excitatory and inhibitory mechanisms.The twin correlations and the structural equation modeling suggested modest heritability for both inhibitory mechanisms. Sexual excitation, in contrast, was not influenced by genetic effects and similarities between twins for this mechanism seemed to be caused by the common environment of the twins.
    Associations between number of children, pregnancy, and overall relationship satisfaction were explored in a population-based sample of 2081 women, aged 33–43 years. Multiparous women had less orgasm problems compared to nulliparous... more
    Associations between number of children, pregnancy, and overall relationship satisfaction were explored in a population-based sample of 2081 women, aged 33–43 years. Multiparous women had less orgasm problems compared to nulliparous women. Nulliparous women had more pain problems and were sexually less satisfied compared to women with children, regardless of the number. Women pregnant with the first child had fewer pain problems compared to a matched nonpregnant control and were sexually more satisfied. Being more satisfied with the overall relationship was related to higher sexual satisfaction and less sexual function problems.
    OBJECTIVE. Body image and perceived attractiveness were examined, and the impact of age, gender, and body mass index (BMI) was analyzed and discussed from an evolutionary and a sociocultural perspective. METHOD. The population-based... more
    OBJECTIVE. Body image and perceived attractiveness were examined, and the impact of age, gender, and body mass index (BMI) was analyzed and discussed from an evolutionary and a sociocultural perspective. METHOD. The population-based sample consisted of 11,468 Finnish men and women aged 18 to 49 years. RESULTS. Both age-related decrease and increase in body satisfaction was detected as well as interactions between age and gender. Some effects were nonlinear. Women were generally less satisfied with their bodies than men. BMI had a stronger influence on women's body image than men's. DISCUSSION. It was proposed that it is insufficient to merely study how age affects general body image because adults might become more satisfied with some aspects of their bodies as a function of age and less satisfied with other aspects. Body satisfaction might also fluctuate during different phases of the adult life, and the patterns possibly differ between men and women.
    Sexual body image was examined in a population-based sample of 9,532 Finnish men and women, age 18 to 49 years. More than one half of women and men were satisfied with their genitals, one half of the women were satisfied with their... more
    Sexual body image was examined in a population-based sample of 9,532 Finnish men and women, age 18 to 49 years. More than one half of women and men were satisfied with their genitals, one half of the women were satisfied with their breasts. Higher levels of genital satisfaction were related to higher frequencies of sexual behavior and better sexual function for both genders. For men, penis size satisfaction was associated with lower levels of premature ejaculation and better erectile function. Sexual body image was related to overall perceived attractiveness, for women a higher body mass index was related to satisfaction with breast size. Having children was negatively related to women's sexual body image, abortions and miscarriages likewise. Limitations of the study and clinical implications of the findings are discussed.
    The factor structure and reliability of the Female Sexual Function Index (FSFI) was evaluated in a Finnish population based sample of 2,081 women, age 33–43 years. In addition, associations between female sexual function and age,... more
    The factor structure and reliability of the Female Sexual Function Index (FSFI) was evaluated in a Finnish population based sample of 2,081 women, age 33–43 years. In addition, associations between female sexual function and age, psychological distress, alcohol use, hormone based contraceptives, child sexual abuse (CSA), and adult sexual abuse were examined. The results supported a six factor solution for the FSFI with high internal consistencies, in line with earlier research in clinical populations. Psychological distress was positively associated with every dimension of the FSFI except desire problems. Age was associated with fewer pain problems. Alcohol use was associated with every dimension of the FSFI, but the direction of the association depended on if it was drinking in general or in connection to intercourse. More drinking in general was related to fewer sexual function problems while drinking in connection to intercourse was related to more sexual function problems. No significant correlation was found between adult sexual abuse and sexual function but between CSA and lubrication, satisfaction, and pain problems. Usage of oral contraceptive pill was not significantly associated with sexual function. The use of hormone based intrauterine systems was significantly associated with less pain and more desire, arousal, and satisfaction. In conclusion, the study supports use of the FSFI for assessing sexual function not only in clinical samples but also in population based samples. The associations found between sexual function and other important variables showed the complexity of sexual function.
    The genetic and environmental influences on sexual coercion, and to what extent its associations with alcohol use and psychopathy depend on shared genetic and environmental effects, were explored in a Finnish population-based sample of... more
    The genetic and environmental influences on sexual coercion, and to what extent its associations with alcohol use and psychopathy depend on shared genetic and environmental effects, were explored in a Finnish population-based sample of 938 men, aged 33–43 years, using the classical twin study design. All three phenotypes were associated positively and affected by genes (sexual coercion 28%, alcohol use 60%, psychopathy 54%), with 46% of the correlation between sexual coercion and psychopathy, 89% of the correlation between alcohol use and psychopathy and 100% of the correlation between sexual coercion and alcohol use being explained by shared genetic effects. Further, the results showed that a proportion of the variance in sexual coercion was derived from a highly genetic source that was common with alcohol use and psychopathy. This latent factor was hypothesized to reflect a general tendency for antisocial behavior that is pervasive across different situations. Relevant theories on sexual coercion were discussed in light of the results. Aggr. Behav. 34:190–202, 2008. © 2007 Wiley-Liss, Inc.
    We explored if the disposition to react with aggression while alcohol intoxicated was moderated by polymor-phic variants of the oxytocin receptor gene (OXTR). Twelve OXTR polymorphisms were genotyped in 116 Finnish men [aged 18–30, M =... more
    We explored if the disposition to react with aggression while alcohol intoxicated was moderated by polymor-phic variants of the oxytocin receptor gene (OXTR). Twelve OXTR polymorphisms were genotyped in 116 Finnish men [aged 18–30, M = 22.7, standard deviation (SD) = 2.4] who were randomly assigned to an alcohol condition in which they received an alcohol dose of 0.7 g pure ethanol/kg body weight or a placebo condition. Aggressive behavior was measured using a laboratory paradigm in which it was operationalized as the level of aversive noise administered to a fictive opponent. No main effects of the polymorphisms on aggressive behavior were found after controlling for multiple testing. The interactive effects between alcohol and two of the OXTR polymorphisms (rs4564970 and rs1488467) on aggressive behavior were nominally significant and remained significant for the rs4564970 when controlled for multiple tests. To the best of our knowledge, this is the first experimental study suggesting interactive effects of specific genetic variants and alcohol on aggressive behavior in humans.