Bipolar Disorder and Bone Mineral Density Z-Scores in Relation to Clinical Characteristics and Lithium Medication.

Bipolar disorder is associated with a long range of medical comorbidities, including migraine, diabetes, and cardiovascular disease. Bipolar disorder has also been associated with an increased risk of bone fractures. Osteoporosis is a reduction in bone mineral density, which leads to an increased risk for fragility fractures. Currently there is limited research on the association between bipolar disorder and osteoporosis. We aimed to study the association between high and low bone mineral density in relation to disease and treatment history in a sample of bipolar patients. We found that bipolar patients with high bone mineral density were more often on lithium medication, had a more active lifestyle and expressed lower current disease burden. Low mineral density was not associated with any of the addressed aspects of disease and treatment history. In conclusion our results support that patients on lithium treatment have higher bone mineral density; further studies are needed to address if lithium medication causes an increase in bone mineral density, and lowers the risk of bone fractures in bipolar disorder.

Hyper- and hypocortisolism in bipolar disorder - A beneficial influence of lithium on the HPA-axis?

BACKGROUND: A hyperactive hypothalamic-pituitary-adrenal axis (HPA-axis) is a well-known phenomenon in bipolar disorder (BD). However, hypocortisolism has also been described and found associated with depression, low quality of life and cardiovascular risk factors in BD patients. Although the pathophysiology related to hypocortisolism in BD is largely unknown, hypocortisolism is associated with chronic stress exposure and after inducing an initial rise in cortisol long-term stress may result in a transition to hypocortisolism. BD patients are throughout life often exposed to chronic stress. We therefore hypothesized that higher age would be associated with lower HPA-axis activity especially among patients without previous mood stabilizing treatment. METHODS: This cross-sectional study consisted of 159 bipolar outpatients and 258 controls. A low-dose-dexamethasone-suppression-test (DST) was used to measure HPA-axis activity. RESULTS: Patients with BD showed a negative association between post DST cortisol and age (-3.0 nmol/l per year; p=0.007). This association gradually increased in subgroups that were naïve to lithium (-7.7 nmol/l per year; p=0.001) and "all mood stabilizers" (-11.4 nmol/l per year; p=0.004). Patients exhibiting hypercortisolism were characterized by younger age and female gender, whereas patients exhibiting hypocortisolism were characterized by long disease duration without prophylactic lithium treatment as well as absence of current lithium medication. LIMITATIONS: Cross sectional study design. CONCLUSIONS: There was a negative association between HPA-axis activity and age in BD, rendering BD patients at risk for developing hypocortisolism. This association was most pronounced among patients without previous or current lithium prophylaxis.

Association between gastrointestinal symptoms and affectivity in patients with bipolar disorder.

AIM: To study if anxiety, depression and experience of stress are associated with gastrointestinal (GI) symptoms in patients with bipolar disorder. METHODS: A total of 136 patients with bipolar disorder (mean age 49.9 years; 61% women) and 136 controls from the general population (mean age 51.0 years; 60% women) were included in the study. GI symptoms were assessed with The Gastrointestinal Symptom Rating Scale-irritable bowel syndrome (GSRS-IBS), level of anxiety and depression with The Hospital Anxiety and Depression Scale (HADS) and stress-proneness with Perceived Stress Questionnaire. Over a ten year period, all visits in primary care were retrospectively recorded in order to identify functional GI disorders. RESULTS: In subjects with low total HADS-score, there were no significant differences in GI-symptoms between patients and controls (GSRS-IBS 7.0 vs 6.5, P = 0.513). In the patients with bipolar disorder there were significant correlations between all GSRS and HADS subscores for all symptom clusters except for "constipation" and "reflux". Factors associated to GI symptoms in the patient group were female sex (adjusted OR = 2.37, 95%CI: 1.07-5.24) and high HADS-Depression score (adjusted OR = 3.64, 95%CI: 1.07-12.4). These patients had also significantly more visits for IBS than patients with low HADS-Depression scores (29% vs 8%, P = 0.008). However, there was no significant differences in consulting behaviour for functional GI disorders between patients and controls (25% vs 17%, P = 0.108). CONCLUSION: Female patients and patients with high HADS depression score reported significantly more GI symptoms, whereas patients with low HADS scores did not differ from control subjects.

Relative hypocortisolism is associated with obesity and the metabolic syndrome in recurrent affective disorders.

BACKGROUND: Cardiovascular disease (CVD) is one of the main causes of excess deaths in affective disorders. Affective disorders are associated with increased frequencies of CVD risk-factors such as obesity, dyslipidemia, and metabolic syndrome. Stress-induced chronic cortisol excess has been suggested to promote obesity and metabolic syndrome. Chronic stress with frequent or persisting hypothalamic-pituitary-adrenal-axis (HPA-axis) hyperactivity may, over time, lead to a state of low HPA-axis activity, also denoted hypocortisolism. A low-dose weight-adjusted dexamethasone-suppression-test (DST) is considered to be a sensitive measure of hypocortisolism. METHODS: 245 patients with recurrent depression or bipolar disorder and 258 controls participated in a low-dose DST and were also examined with regard to metabolic status. RESULTS: Patients with hypocortisolism (low post-DST cortisol) compared with patients without hypocortisolism (normal or high post-DST cortisol) exhibited increased odds ratios (OR) for obesity (OR=4.0), overweight (OR=4.0), large waist (OR=2.7), high LDL (OR=4.2), low HDL (OR=2.4), high LDL/HDL ratio (OR=3.3), high TC/HDL ratio (OR=3.4) and metabolic syndrome (OR=2.0). A similar pattern but less pronounced was also found in the control sample. LIMITATIONS: The cross sectional study design and absence of analyses addressing lifestyle factors. CONCLUSIONS: Our findings suggest that a substantial portion of the metabolic disorders and cardiovascular risk factors seen in recurrent affective disorders are found among individuals exhibiting hypocortisolism. This might indicate that long-term stress is a central contributor to metabolic abnormalities and CVD mortality in recurrent affective disorders.

A network of synaptic genes associated with schizophrenia and bipolar disorder.

Identification of novel candidate genes for schizophrenia (SZ) and bipolar disorder (BP), two psychiatric disorders with large epidemiological impacts, is a key research area in neurosciences and psychiatric genetics. Previous evidence from genome-wide studies suggests an important role for genes involved in synaptic plasticity in the risk for SZ and BP. We used a convergent genomics approach, combining different lines of biological evidence, to identify genes involved in the cAMP/PKA/CREB functional pathway that could be novel candidates for BP and SZ: CREB1, CREM, GRIN2C, NPY2R, NF1, PPP3CB and PRKAR1A. These 7 genes were analyzed in a HapMap based association study comprising 48 common SNPs in 486 SZ, 351 BP patients and 514 control individuals recruited from an isolated population in Northern Sweden. Genetic analysis showed significant allelic associations of SNPs in PRKAR1A with SZ and of PPP3CB and PRKAR1A with BP. Our results highlight the feasibility and the importance of convergent genomic data analysis for the identification of candidate genes and our data provide support for the role of common inherited variants in synaptic genes and their involvement in the etiology of BP and SZ.

Hypothalamus-Pituitary-Adrenal Axis Hypersuppression Is Associated with Gastrointestinal Symptoms in Major Depression.

BACKGROUND/AIMS: Gastrointestinal symptoms and hypothalamus-pituitary-adrenal (HPA) axis dysfunction are frequently observed in patients with major depression. The primary aim of the study was to investigate the relationship between HPA-axis function and self-perceived functional gastrointestinal symptoms in major depression. METHODS: Patients with major depression (n = 73) and controls representative of the general population (n = 146) underwent a weight adjusted very low dose dexamethasone suppression test (DST). Patients and controls completed the gastrointestinal symptom rating scale-iritable bowel syndrome (GSRS-IBS) and the hospital anxiety depression scale. Medical records of the patients were screened over a ten year period for functional gastrointestinal disorder and pain conditions. RESULTS: Patients with high GSRS-IBS scores (above median) exhibited HPA-axis hypersuppression more often than controls (defined by the lowest 10% cutoff of the post-DST cortisol values among controls, adjusted OR 7.25, CI 1.97-26.7) whereas patients with low GSRS-IBS scores did not differ from controls concerning their post-DST cortisol values. Patients who had consulted primary care for functional gastrointestinal disorder (P = 0.039), lumbago (P = 0.006) and chronic multifocal pain (P = 0.057) also exhibited an increased frequency of hypersuppression. CONCLUSIONS: HPA-axis hypersuppression is associated with functional gastrointestinal symptoms in patients with major depression.

Relative hypo- and hypercortisolism are both associated with depression and lower quality of life in bipolar disorder: a cross-sectional study.

BACKGROUND: Depression in unipolar and bipolar disorders is associated with hypothalamic-pituitary-adrenal-axis (HPA-axis) hyperactivity. Also, unipolar disorder has recently been shown to exhibit HPA-axis hypoactivity. We studied for the first time how HPA-axis hypo- and hyperactivity relate to depression and disease burden in bipolar disorder. We were interested in studying hypocortisolism; characterized by increased HPA-axis negative feedback sensitivity and lower basal cortisol levels together with the opposite HPA-axis regulatory pattern of hypercortisolism. METHODS: This cross-sectional study includes 145 type 1 and 2 bipolar outpatients and 145 matched controls. A dexamethasone-suppression-test (DST) measures the negative feedback sensitivity and a weight-adjusted very-low-dose DST was employed, which is sensitive in identifying hypocortisolism and hypercortisolism. The 25th and 75th percentiles of control post-DST values were used as cut-offs identifying patients exhibiting relative hypo-, and hypercortisolism. Self-report questionnaires were employed: Beck-Depression-Inventory (BDI), Montgomery-Åsberg-Depression-Rating-Scale (MADRS-S), World-Health-Organization-Quality-of-Life-Assessment-100 and Global-Assessment-of-Functioning. RESULTS: Patients exhibiting relative hypocortisolism expectedly exhibited lowered basal cortisol levels (p = 0.046). Patients exhibiting relative hypercortisolism expectedly exhibited elevated basal levels (p<0.001). Patients exhibiting relative hypocortisolism showed 1.9-2.0 (BDI, p = 0.017, MADRS-S, p = 0.37) and 6.0 (p<0.001) times increased frequencies of depression and low overall life quality compared with patients exhibiting mid post-DST values (eucortisolism). Adjusted Odds Ratios (OR:s) for depression ranged from 3.8-4.1 (BDI, p = 0.006, MADRS-S, p = 0.011) and was 23.4 (p<0.001) for life quality. Patients exhibiting relative hypercortisolism showed 1.9-2.4 (BDI, p = 0.017, MADRS-S, p = 0.003) and 4.7 (p<0.001) times higher frequencies of depression and low overall life quality compared with patients exhibiting eucortisolism. Adjusted OR:s for depression ranged from 2.2-2.7 (BDI, p = 0.068, MADRS-S, p = 0.045) and was 6.3 (p = 0.008) for life quality. LIMITATIONS: The cross-sectional design and lack of pre-established reference values of the DST employed. CONCLUSIONS: Relative hypocortisolism and relative hypercortisolism were associated with depression and lower life quality, providing novel insights into the detrimental role of stress in bipolar disorder.

Shorter telomere length is linked to brain atrophy and white matter hyperintensities.

BACKGROUND: leukocyte telomere length (TL) is considered a marker of biological aging. Several studies have investigated the link between leukocyte TL and aging-associated functional attributes of the brain, but no prior study has investigated whether TL can be linked to brain atrophy and white matter hyperintensities (WMHs); two prominent structural manifestations of brain aging. METHODS: we investigated whether leukocyte TL was related to brain atrophy and WMHs in a sample of 102 non-demented individuals aged 64-75 years. RESULTS: shorter TL was related to greater degree of subcortical atrophy (ß = -0.217, P = 0.034), but not to cortical atrophy. Furthermore, TL was 371 bp shorter (P = 0.041) in participants exhibiting subcortical WMHs, and 552 bp shorter (P = 0.009) in older participants exhibiting periventricular WMHs. CONCLUSION: this study provides the first evidence of leukocyte TL being associated with cerebral subcortical atrophy and WMHs, lending further support to the concept of TL as a marker of biological aging, and in particular that of the aging brain.

Rare copy number variants in neuropsychiatric disorders: Specific phenotype or not?

From a number of genome-wide association studies it was shown that de novo and/or rare copy number variants (CNVs) are found at an increased frequency in neuropsychiatric diseases. In this study we examined the prevalence of CNVs in six genomic regions (1q21.1, 2p16.3, 3q29, 15q11.2, 15q13.3, and 16p11.2) previously implicated in neuropsychiatric diseases. Hereto, a cohort of four neuropsychiatric disorders (schizophrenia, bipolar disorder, major depressive disorder, and intellectual disability) and control individuals from three different populations was used in combination with Multilpex Amplicon Quantifiaction (MAQ) assays, capable of high resolution (kb range) and custom-tailored CNV detection. Our results confirm the etiological candidacy of the six selected CNV regions for neuropsychiatric diseases. It is possible that CNVs in these regions can result in disturbed brain development and in this way lead to an increased susceptibility for different neuropsychiatric disorders, dependent on additional genetic and environmental factors. Our results also suggest that the neurodevelopmental component is larger in the etiology of schizophrenia and intellectual disability than in mood disorders. Finally, our data suggest that deletions are in general more pathogenic than duplications. Given the high frequency of the examined CNVs (1-2%) in patients of different neuropsychiatric disorders, screening of large cohorts with an affordable and feasible method like the MAQ assays used in this study is likely to result in important progress in unraveling the genetic factors leading to an increased susceptibility for several psychiatric disorders.

Longer leukocyte telomere length is associated with smaller hippocampal volume among non-demented APOE ε3/ε3 subjects.

Telomere length shortens with cellular division, and leukocyte telomere length is used as a marker for systemic telomere length. The hippocampus hosts adult neurogenesis and is an important structure for episodic memory, and carriers of the apolipoprotein E ε4 allele exhibit higher hippocampal atrophy rates and differing telomere dynamics compared with non-carriers. The authors investigated whether leukocyte telomere length was associated with hippocampal volume in 57 cognitively intact subjects (29 ε3/ε3 carriers; 28 ε4 carriers) aged 49-79 yr. Leukocyte telomere length correlated inversely with left (r(s) = -0.465; p = 0.011), right (r(s) = -0.414; p = 0.025), and total hippocampus volume (r(s) = -0.519; p = 0.004) among APOE ε3/ε3 carriers, but not among ε4 carriers. However, the ε4 carriers fit with the general correlation pattern exhibited by the ε3/ε3 carriers, as ε4 carriers on average had longer telomeres and smaller hippocampi compared with ε3/ε3 carriers. The relationship observed can be interpreted as long telomeres representing a history of relatively low cellular proliferation, reflected in smaller hippocampal volumes. The results support the potential of leukocyte telomere length being used as a biomarker for tapping functional and structural processes of the aging brain.

Identification of a CACNA2D4 deletion in late onset bipolar disorder patients and implications for the involvement of voltage-dependent calcium channels in psychiatric disorders.

The GWAS-based association of CACNA1C with bipolar disorder (BPD) is one of the strongest genetic findings to date. CACNA1C belongs to the family of CACN genes encoding voltage-dependent calcium channels (VDCCs). VDCCs are involved in brain circuits and cognitive processes implicated in BPD and schizophrenia (SZ). Recently, it was shown that rare copy number variations (CNVs) are found at an increased frequency in SZ and to a lesser extent also in BPD, suggesting the involvement of CNVs in the causation of these diseases. We hypothesize that CNVs in CACN genes can influence the susceptibility to BPD, SZ, and/or schizoaffective disorder (SZA). A search for CNVs in eight CACN genes in a patient-control sample of European decent was performed. A total of 709 BP patients, 645 SZ patients, 189 SZA patients, and 1,470 control individuals were screened using the Multiplex Amplicon Quantification (MAQ) method. We found a rare, partial deletion of 35.7 kb in CACNA2D4 in two unrelated late onset bipolar I patients and in one control individual. All three deletions shared the same breakpoints removing exons 17-26 of CACNA2D4, comprising part of the CACHE domain. Based on the data we cannot claim causality to BPD of the identified CACNA2D4 deletion but nevertheless this deletion can be important in unraveling the underlying processes leading to psychiatric diseases in general and BPD in particular.

APOE ε4 is associated with longer telomeres, and longer telomeres among ε4 carriers predicts worse episodic memory.

Both leukocyte telomere length and the apolipoprotein ε4 allele have been associated with mortality, cardiovascular disease, cognition, and dementia. The authors investigated whether leukocyte telomere length was associated with APOE genotype or cognitive abilities in the context of APOE genotype. The setting for this cross-sectional study was 427 nondemented individuals aged 41-81 yr. The authors found that ε4 carriers overall exhibited significantly longer telomeres compared with non-carriers (difference of 268 bp, p = 0.001). This difference was greatest at the lower limit of the age span and nonsignificant at the upper limit, which translated into a significantly higher telomere attrition rate (p = 0.049) among ε4 carriers (37 bp/years) compared with non-carriers (21 bp/year). Further, longer telomeres among ε4 carriers significantly predicted worse performance on episodic memory tasks. No significant associations were found on tasks tapping semantic and visuospatial ability, or among ε3/ε3 carriers. In conclusion, APOE ε4 carriers had longer telomeres compared with non-carriers, but higher rate of attrition. Among them, longer telomeres predicted worse performance on episodic memory tasks. These observations suggest that the ε4 allele is associated with abnormal cell turnover of functional and possibly clinical significance.

Short telomeres in depression and the general population are associated with a hypocortisolemic state.

BACKGROUND: The hypothalamic-pituitary-adrenal (HPA) axis plays a central role in stress regulation, and leukocyte telomere length (TL) has been suggested to represent a cumulative measure of stress. Depression is intimately related with stress and frequently exhibits a dysregulated HPA axis. We aimed to study the relationships between TL and biological and psychological facets of stress in recurrent major depressive disorder and controls. METHODS: Leukocyte TL was measured in 91 subjects with recurrent major depressive disorder and 451 control subjects. Stress was assessed from both a biological perspective, by assessing HPA axis function with a weight-adjusted very-low-dose dexamethasone suppression test (DST), and a psychological perspective, with self-report questionnaires. RESULTS: TL was shorter among patients compared with control subjects (277 base pairs, p = .001). Overall, short TL was associated with a hypocortisolemic state (low post-DST cortisol and high percentage of cortisol reduction after the DST) among both patients and control subjects but more pronounced among patients. This state, which was overrepresented among patients, was characterized by high familial loading of affective disorders among patients (p = .001) and high C-reactive protein levels among control subjects (p = .040). TL was also inversely associated with stress measured with the Perceived Stress Questionnaire (r(s) = -.258, p = .003). CONCLUSIONS: Short TL is associated with depression and hypocortisolism. Because hypocortisolism has been shown to develop from chronic stress exposure, our findings corroborate the concept of TL as a cumulative measure of stress and provide novel insights into the detrimental role of stress in depressive illness and the general population.

Evidence for the involvement of the glucocorticoid receptor gene in bipolar disorder in an isolated northern Swedish population.

OBJECTIVES: Dysfunction of the hypothalamus-pituitary-adrenal (HPA) axis is one of the most consistent findings in the pathophysiology of mood disorders. The potential role of genes related to HPA axis function has been investigated extensively in major depression. However, in bipolar disorder (BPD) such studies are scarce. We performed a systematic HapMap-based association study of six genes crucial for HPA axis function in relation to BPD. METHODS: Haplotype tagging single nucleotide polymorphisms (htSNPs) were selected in order to identify all haplotypes with a frequency of more than 1% in the genes encoding the glucocorticoid receptor (GR), mineralocorticoid receptor (MR), corticotrophin releasing hormone receptor 1 (CRH-R1) and 2 (CRH-R2), CRH binding protein (CRH-BP), and FK binding protein 5 (FKBP5). This resulted in a total selection of 225 SNPs that were genotyped and analyzed in 309 BPD patients and 364 matched control individuals all originating from an isolated northern Swedish population. RESULTS: Consistent evidence for an association with BPD was found for NR3C1, the gene encoding GR. Almost all SNPs in two adjacent haplotype blocks contributed to the positive signal, comprised of significant single marker, sliding window, and haplotype-specific p-values. All these results point to a moderately frequent (10-15%) susceptibility haplotype covering the entire coding region and 3' untranslated region (UTR) of NR3C1. CONCLUSIONS: This study contributes to the growing evidence for a role of the glucocorticoid receptor gene (NR3C1) in vulnerability to mood disorders, and BPD in particular, and warrants further in vitro investigation of the at-risk haplotypes with respect to disease etiology. However, this association might be restricted to this specific population, as it is observed in a rather small sample from an isolated population without replication, and data from large meta-analyses for genome-wide association studies in BPD do not show the GR as a very strong candidate.

Sequencing of DISC1 pathway genes reveals increased burden of rare missense variants in schizophrenia patients from a northern Swedish population.

In recent years, DISC1 has emerged as one of the most credible and best supported candidate genes for schizophrenia and related neuropsychiatric disorders. Furthermore, increasing evidence--both genetic and functional--indicates that many of its protein interaction partners are also involved in the development of these diseases. In this study, we applied a pooled sample 454 sequencing strategy, to explore the contribution of genetic variation in DISC1 and 10 of its interaction partners (ATF5, Grb2, FEZ1, LIS-1, PDE4B, NDE1, NDEL1, TRAF3IP1, YWHAE, and ZNF365) to schizophrenia susceptibility in an isolated northern Swedish population. Mutation burden analysis of the identified variants in a population of 486 SZ patients and 514 control individuals, revealed that non-synonymous rare variants with a MAF<0.01 were significantly more present in patients compared to controls (8.64% versus 4.7%, P = 0.018), providing further evidence for the involvement of DISC1 and some of its interaction partners in psychiatric disorders. This increased burden of rare missense variants was even more striking in a subgroup of early onset patients (12.9% versus 4.7%, P = 0.0004), highlighting the importance of studying subgroups of patients and identifying endophenotypes. Upon investigation of the potential functional effects associated with the identified missense variants, we found that ∼90% of these variants reside in intrinsically disordered protein regions. The observed increase in mutation burden in patients provides further support for the role of the DISC1 pathway in schizophrenia. Furthermore, this study presents the first evidence supporting the involvement of mutations within intrinsically disordered protein regions in the pathogenesis of psychiatric disorders. As many important biological functions depend directly on the disordered state, alteration of this disorder in key pathways may represent an intriguing new disease mechanism for schizophrenia and related neuropsychiatric diseases. Further research into this unexplored domain will be required to elucidate the role of the identified variants in schizophrenia etiology.

The relationship between the val158met catechol-O-methyltransferase (COMT) polymorphism and irritable bowel syndrome.

BACKGROUND: The catechol-O-methyltransferase (COMT) enzyme has a key function in the degradation of catecholamines and a functional polymorphism is val158met. The val/val genotype results in a three to fourfold higher enzymatic activity compared with the met/met genotype, with the val/met genotype exhibiting intermediate activity. Since pain syndromes as well as anxiety and depression are associated to low and high COMT activity respectively and these conditions are all associated with irritable bowel syndrome (IBS) we wanted for the first time to explore the relationship between the polymorphism and IBS. METHODOLOGY/PRINCIPAL FINDINGS: 867 subjects (445 women) representative of the general population and 70 consecutively sampled patients with IBS (61 women) were genotyped for the val158met polymorphism and the IBS patients filled out the Hospital-Anxiety-and-Depression-Scale (HADS) questionnaire, and an IBS symptom diary. RESULTS: There was a significantly higher occurrence of the val/val genotype in patients compared with controls (30% vs 20%; Chi(2) (1) 3.98; p = 0.046) and a trend toward a lower occurrence of the val/met genotype in IBS patients compared with controls (39% vs 49%; Chi(2) (1) 2.89; p = 0.089). Within the IBS patients the val/val carriers exhibited significantly increased bowel frequency (2.6 vs 1.8 stools per day; Chi(2) (1) 5.3; p = 0.03) and a smaller proportion of stools with incomplete defecation (41% vs 68%; Chi(2) (1) 4.3; p = 0.04) compared with the rest (val/met+met/met carriers). The val/val carriers also showed a trend for a smaller proportion of hard stools (0% vs 15%; Chi(2) (1) 3.2; p = 0.08) and a higher frequency of postprandial defecation (26% vs 21%; Chi(2) (1) 3.0; p = 0.08). CONCLUSIONS/SIGNIFICANCE: In this study we found an association between the val/val genotype of the val158met COMT gene and IBS as well as to specific IBS related bowel pattern in IBS patients.

Dual association of a TRKA polymorphism with schizophrenia.

OBJECTIVE: An interaction between predisposing genes and environmental stressors is thought to underlie the neurodevelopmental disorder schizophrenia. In a targeted gene screening, we previously found that the minor allele of the single nucleotide polymorphism (SNP) rs6336 in the neurotrophic tyrosine kinase receptor 1 (NTRK1/TRKA) gene is associated with schizophrenia as a risk factor. METHODS: We genotyped the TRKA SNP in a total of eight independent Caucasian schizophrenia case-control groups. RESULT: Remarkably, although in five of the groups a higher frequency of the risk allele was indeed found in the patients compared with the controls, in the three other groups the SNP acted as a protective factor. CONCLUSION: An intriguing possibility is that this dual character of the TRKA SNP is caused by its interaction with endophenotypic and/or epistatic factors.

PCM1 and schizophrenia: a replication study in the Northern Swedish population.

Previous studies implicated centrosomal dysfunction as a source of various neuropsychiatric disorders, including schizophrenia (SZ). Two recent reports [Gurling et al., 2006; Datta et al., 2008. Mol Psychiatry] described an association between polymorphisms in the PCM1 gene and SZ in a UK/Scottish population. In this study, we aimed to replicate these findings in a Northern Swedish association sample of 486 research subjects with SZ and 512 unrelated control individuals. We genotyped 12 previously described SNP markers and carried out haplotype analyses using the same multi-marker haplotypes previously reported. Though we could not replicate the association with SNPs rs445422 and rs208747, we did observe a significant protective association with intronic SNP rs13276297. Furthermore, we performed a meta-analysis comprising 1,794 SZ patients and 1,553 controls, which confirmed the previously reported association with rs445422 and rs208747. These data provide further evidence that PCM1-though certainly not a major risk factor in the Northern Swedish population-cannot be ruled out as a contributor to SZ risk and/or protection, and deserves further replication in larger populations to elucidate its role in disease etiology.

Large-scale parent-child comparison confirms a strong paternal influence on telomere length.

Telomere length is documented to have a hereditary component, and both paternal and X-linked inheritance have been proposed. We investigated blood cell telomere length in 962 individuals with an age range between 0 and 102 years. Telomere length correlations were analyzed between parent-child pairs in different age groups and between grandparent-grandchild pairs. A highly significant correlation between the father's and the child's telomere length was observed (r=0.454, P<0.001), independent of the sex of the offspring (father-son: r=0.465, P<0.001; father-daughter: r=0.484, P<0.001). For mothers, the correlations were weaker (mother-child: r=0.148, P=0.098; mother-son: r=0.080, P=0.561; mother-daughter: r=0.297, P=0.013). A positive telomere length correlation was also observed for grandparent-grandchild pairs (r=0.272, P=0.013). Our findings indicate that fathers contribute significantly stronger to the telomere length of the offspring compared with mothers (P=0.012), but we cannot exclude a maternal influence on the daughter's telomeres. Interestingly, the father-child correlations diminished with increasing age (P=0.022), suggesting that nonheritable factors have an impact on telomere length dynamics during life.

Support for NRG1 as a susceptibility factor for schizophrenia in a northern Swedish isolated population.

CONTEXT: Neuregulin 1 (NRG1), a growth factor involved in neurodevelopment, myelination, neurotransmitter receptor expression, and synaptic plasticity, first joined the list of candidate genes for schizophrenia when a 7-marker haplotype at the 5' end of the gene (Hap(ICE)) was shown to be associated with the disorder in the Icelandic population. Since then, more genetic and functional evidence has emerged, which supports a role for NRG1 in the development of schizophrenia. OBJECTIVE: To determine the contribution of NRG1 to susceptibility for schizophrenia in a northern Swedish isolated population. DESIGN: Detailed linkage disequilibrium (LD)-based patient-control association study. This is the first study to type and analyze the 7 Hap(ICE) markers and a set of 32 HapMap tagging single-nucleotide polymorphisms (SNPs) that represents variants with a minor allele frequency of at least 1% and fully characterizes the LD structure of the 5' part of NRG1. SETTING: Outpatient and inpatient hospitals. PARTICIPANTS: A total of 486 unrelated patients with schizophrenia and 514 unrelated control individuals recruited from a northern Swedish isolated population. MAIN OUTCOME MEASURES: Association between markers and disease. RESULTS: Analysis of the Hap(ICE) markers showed the association of a 7-marker and 2-microsatellite haplotype, different from the haplotypes associated in the Icelandic population and overrepresented in northern Swedish control individuals. Subsequently, a more detailed analysis that included all 37 genotyped SNPs was performed by investigating haplotypic association, dependent and independent of LD block structure. We found significant association with 5 SNPs located in the second intron of NRG1 (.007