Mikael Landén

The Age of Olfactory Bulb Neurons in Humans

Continuous turnover of neurons in the olfactory bulb is implicated in several key aspects of olfaction. There is a dramatic decline postnatally in the number of migratory neuroblasts en route to the olfactory bulb in humans, and it has been unclear to what extent the small number of neuroblasts at later stages contributes new neurons to the olfactory bulb. We have assessed the age of olfactory bulb neurons in humans by measuring the levels of nuclear bomb test-derived (14)C in genomic DNA. We report that (14)C concentrations correspond to the atmospheric levels at the time of birth of the individuals, establishing that there is very limited, if any, postnatal neurogenesis in the human olfactory bulb. This identifies a fundamental difference in the plasticity of the human brain compared to other mammals.

Long-term follow-up of transsexual persons undergoing sex reassignment surgery: Cohort study in Sweden

Context The treatment for transsexualism is sex reassignment, including hormonal treatment and surgery aimed at making the persons body as congruent with the opposite sex as possible. There is a dearth of long term, follow-up studies after sex reassignment. Objective To estimate mortality, morbidity, and criminal rate after surgical sex reassignment of transsexual persons. Design A population-based matched cohort study. Setting Sweden, 1973-2003. Participants All 324 sex-reassigned persons (191 male-to-females, 133 female-to-males) in Sweden, 1973–2003. Random population controls (10∶1) were matched by birth year and birth sex or reassigned (final) sex, respectively. Main Outcome Measures Hazard ratios (HR) with 95% confidence intervals (CI) for mortality and psychiatric morbidity were obtained with Cox regression models, which were adjusted for immigrant status and psychiatric morbidity prior to sex reassignment (adjusted HR [aHR]). Results The overall mortality for sex-reassigned persons was higher during follow-up (aHR 2.8; 95% CI 1.8–4.3) than for controls of the same birth sex, particularly death from suicide (aHR 19.1; 95% CI 5.8–62.9). Sex-reassigned persons also had an increased risk for suicide attempts (aHR 4.9; 95% CI 2.9–8.5) and psychiatric inpatient care (aHR 2.8; 95% CI 2.0–3.9). Comparisons with controls matched on reassigned sex yielded similar results. Female-to-males, but not male-to-females, had a higher risk for criminal convictions than their respective birth sex controls. Conclusions Persons with transsexualism, after sex reassignment, have considerably higher risks for mortality, suicidal behaviour, and psychiatric morbidity than the general population. Our findings suggest that sex reassignment, although alleviating gender dysphoria, may not suffice as treatment for transsexualism, and should inspire improved psychiatric and somatic care after sex reassignment for this patient group.

Polygenic dissection of diagnosis and clinical dimensions of bipolar disorder and schizophrenia

Bipolar disorder and schizophrenia are two often severe disorders with high heritabilities. Recent studies have demonstrated a large overlap of genetic risk loci between these disorders but diagnostic and molecular distinctions still remain. Here, we perform a combined genome-wide association study (GWAS) of 19 779 bipolar disorder (BP) and schizophrenia (SCZ) cases versus 19 423 controls, in addition to a direct comparison GWAS of 7129 SCZ cases versus 9252 BP cases. In our case–control analysis, we identify five previously identified regions reaching genome-wide significance (CACNA1C, IFI44L, MHC, TRANK1 and MAD1L1) and a novel locus near PIK3C2A. We create a polygenic risk score that is significantly different between BP and SCZ and show a significant correlation between a BP polygenic risk score and the clinical dimension of mania in SCZ patients. Our results indicate that first, combining diseases with similar genetic risk profiles improves power to detect shared risk loci and second, that future direct comparisons of BP and SCZ are likely to identify loci with significant differential effects. Identifying these loci should aid in the fundamental understanding of how these diseases differ biologically. These findings also indicate that combining clinical symptom dimensions and polygenic signatures could provide additional information that may someday be used clinically.

Genome-wide association study in a Swedish population yields support for greater CNV and MHC involvement in schizophrenia compared with bipolar disorder

Schizophrenia (SCZ) and bipolar disorder (BD) are highly heritable psychiatric disorders with overlapping susceptibility loci and symptomatology. We conducted a genome-wide association study (GWAS) of these disorders in a large Swedish sample. We report a new and independent case–control analysis of 1507 SCZ cases, 836 BD cases and 2093 controls. No single-nucleotide polymorphisms (SNPs) achieved significance in these new samples; however, combining new and previously reported SCZ samples (2111 SCZ and 2535 controls) revealed a genome-wide significant association in the major histocompatibility complex (MHC) region (rs886424, P=4.54 × 10−8). Imputation using multiple reference panels and meta-analysis with the Psychiatric Genomics Consortium SCZ results underscored the broad, significant association in the MHC region in the full SCZ sample. We evaluated the role of copy number variants (CNVs) in these subjects. As in prior reports, deletions were enriched in SCZ, but not BD cases compared with controls. Singleton deletions were more frequent in both case groups compared with controls (SCZ: P=0.003, BD: P=0.013), whereas the largest CNVs (>500 kb) were significantly enriched only in SCZ cases (P=0.0035). Two CNVs with previously reported SCZ associations were also overrepresented in this SCZ sample: 16p11.2 duplications (P=0.0035) and 22q11 deletions (P=0.03). These results reinforce prior reports of significant MHC and CNV associations in SCZ, but not BD.

Effect of buspirone on sexual dysfunction in depressed patients treated with selective serotonin reuptake inhibitors.

To evaluate the possible influence of buspirone on sexual dysfunction in depressed patients treated with a selective serotonin reuptake inhibitor (SSRI), we analyzed data from a placebo-controlled trial designed to explore the efficacy of buspirone as add-on treatment for patients not responding to an SSRI alone. At baseline, all patients met the criteria for a major depressive episode according to DSM-IV and had received citalopram or paroxetine during a minimum of 4 weeks without responding to the treatment. Buspirone (flexible dosage, 20-60 mg/day) or placebo was added to the SSRI for 4 weeks; the mean daily dose of buspirone at endpoint was 48.5 mg (SD = 1.0). Sexual dysfunction was evaluated using a structured interview. Before starting medication with buspirone or placebo, 40% (47 of 117) reported at least one kind of sexual dysfunction (decreased libido, ejaculatory dysfunction, orgasmic dysfunction). During the 4 weeks of treatment, approximately 58% of subjects treated with buspirone reported an improvement with respect to sexual function; in the placebo group, the response rate was 30%. The difference between placebo and active drug treatment was more pronounced in women than in men. The response was obvious during the first week, with no further improvement during the course of the study. It is suggested that the effect of buspirone on sexual dysfunction is a result of a reversal of SSRI-induced sexual side effects rather than of an antidepressant effect of the drug.

Fecundity of Patients With Schizophrenia, Autism, Bipolar Disorder, Depression, Anorexia Nervosa, or Substance Abuse vs Their Unaffected Siblings

CONTEXT It is unknown how genetic variants conferring liability to psychiatric disorders survive in the population despite strong negative selection. However, this is key to understanding their etiology and designing studies to identify risk variants. OBJECTIVES To examine the reproductive fitness of patients with schizophrenia and other psychiatric disorders vs their unaffected siblings and to evaluate the level of selection on causal genetic variants. DESIGN We measured the fecundity of patients with schizophrenia, autism, bipolar disorder, depression, anorexia nervosa, or substance abuse and their unaffected siblings compared with the general population. SETTING Population databases in Sweden, including the Multi-Generation Register and the Swedish Hospital Discharge Register. PARTICIPANTS In total, 2.3 million individuals among the 1950 to 1970 birth cohort in Sweden. MAIN OUTCOME MEASURES Fertility ratio (FR), reflecting the mean number of children compared with that of the general population, accounting for age, sex, family size, and affected status. RESULTS Except for women with depression, affected patients had significantly fewer children (FR range for those with psychiatric disorder, 0.23-0.93; P < 10-10). This reduction was consistently greater among men than women, suggesting that male fitness was particularly sensitive. Although sisters of patients with schizophrenia and bipolar disorder had increased fecundity (FR range, 1.02-1.03; P < .01), this was too small on its own to counterbalance the reduced fitness of affected patients. Brothers of patients with schizophrenia and autism showed reduced fecundity (FR range, 0.94-0.97; P < .001). Siblings of patients with depression and substance abuse had significantly increased fecundity (FR range, 1.01-1.05; P < 10-10). In the case of depression, this more than compensated for the lower fecundity of affected individuals. CONCLUSIONS Our results suggest that strong selection exists against schizophrenia, autism, and anorexia nervosa and that these variants may be maintained by new mutations or an as-yet unknown mechanism. Bipolar disorder did not seem to be under strong negative selection. Vulnerability to depression, and perhaps substance abuse, may be preserved by balancing selection, suggesting the involvement of common genetic variants in ways that depend on other genes and on environment.

Creativity and mental disorder: family study of 300 000 people with severe mental disorder

BACKGROUND There is a long-standing belief that creativity is coupled with psychopathology. AIMS To test this alleged association and to investigate whether any such association is the result of environmental or genetic factors. METHOD We performed a nested case-control study based on Swedish registries. The likelihood of holding a creative occupation in individuals who had received in-patient treatment for schizophrenia, bipolar disorder or unipolar depression between 1973 and 2003 and their relatives without such a diagnosis was compared with that of controls. RESULTS Individuals with bipolar disorder and healthy siblings of people with schizophrenia or bipolar disorder were overrepresented in creative professions. People with schizophrenia had no increased rate of overall creative professions compared with controls, but an increased rate in the subgroup of artistic occupations. Neither individuals with unipolar depression nor their siblings differed from controls regarding creative professions. CONCLUSIONS A familial cosegregation of both schizophrenia and bipolar disorder with creativity is suggested.

Women with polycystic ovary syndrome are often depressed or anxious--a case control study.

OBJECTIVE Polycystic ovary syndrome (PCOS) is a common hyperandrogenic endocrine disorder affecting women of fertile age. The aim of this study was to survey whether the rate of clinical psychiatric disorders in PCOS differs from the normal population. METHOD Women with PCOS (n=49) meeting the Rotterdam criteria for PCOS, and 49 age-matched controls identified from the population registry, were recruited. Trained clinicians used the MINI International Neuropsychiatric Interview to establish lifetime occurrence of Axis I DSM diagnoses. Serum-testosterone and sex hormone binding globulin were analyzed. RESULTS Women with PCOS had higher lifetime incidence of depressive episodes, social phobia, and eating disorders than controls. Suicide attempts were seven times more common in the PCOS group than in the controls. Current as well as lifetime use of antidepressants and anxiolytic drugs were more common in the PCOS group. CONCLUSIONS Previous studies have found that PCOS is associated with decreased quality of life and self-rated mental symptoms. This study demonstrates that PCOS is also linked to psychiatric syndromes as verified by structured clinical assessments. The clinical implication of this study is that clinicians treating women with PCOS should be aware that these women are a high risk group for common affective and anxiety disorders as well as suicide attempts.

Prevalence, incidence and sex ratio of transsexualism

Landén M, Wålinder J, Lundström B. Prevalence, incidence and sex ratio of transsexualism.

Sex steroid-related genes and male-to-female transsexualism.

Transsexualism is characterised by lifelong discomfort with the assigned sex and a strong identification with the opposite sex. The cause of transsexualism is unknown, but it has been suggested that an aberration in the early sexual differentiation of various brain structures may be involved. Animal experiments have revealed that the sexual differentiation of the brain is mainly due to an influence of testosterone, acting both via androgen receptors (ARs) and--after aromatase-catalyzed conversion to estradiol--via estrogen receptors (ERs). The present study examined the possible importance of three polymorphisms and their pairwise interactions for the development of male-to-female transsexualism: a CAG repeat sequence in the first exon of the AR gene, a tetra nucleotide repeat polymorphism in intron 4 of the aromatase gene, and a CA repeat polymorphism in intron 5 of the ERbeta gene. Subjects were 29 Caucasian male-to-female transsexuals and 229 healthy male controls. Transsexuals differed from controls with respect to the mean length of the ERbeta repeat polymorphism, but not with respect to the length of the other two studied polymorphisms. However, binary logistic regression analysis revealed significant partial effects for all three polymorphisms, as well as for the interaction between the AR and aromatase gene polymorphisms, on the risk of developing transsexualism. Given the small number of transsexuals in the study, the results should be interpreted with the utmost caution. Further study of the putative role of these and other sex steroid-related genes for the development of transsexualism may, however, be worthwhile.