Evaluation of a susceptibility gene for schizophrenia on chromosome 6p by multipoint affected sib-pair linkage analysis.

The influence of genetic factors in schizophrenia has been convincingly demonstrated by family, twin and adoption studies, but the mode of transmission remains uncertain. The reported pattern of recurrence risks suggests a set of interacting loci. Based on prior evidence for linkage on chromosome 6p (K. Kendler, pers. comm.), we have scanned the short arm of chromosome 6 in 54 families for loci predisposing to schizophrenia, using 25 microsatellite markers spanning 60 centiMorgans (cM). Allele sharing identity by descent was examined in affected sib-pairs from these families, followed by multipoint sib-pair linkage analysis. Positive lod scores were obtained over a wide region (D6S470 to D6S271), with a maximum lod score of 2.2 occurring near D6S274, located in 6p22. However, we obtained a lod score of -2 at D6S296, the locus found by others to provide the greatest linkage evidence. At D6S274, we report a positive lod score as do Straub et al. (individually non-significant). A combined total lod of 3.6-4.0 suggests the possibility of a susceptibility locus in this region. However, methodological differences between our studies makes a firm conclusion difficult.

Catecholamines and their receptors in blood: evidence for alterations in schizophrenia.

The simultaneous determination of serum catecholamine (CA) and their receptors in blood cells offers the possibility of evaluating disturbances of the dopamine (DA) and noradrenaline (NA) neuronal systems in man. High-affinity binding sites for 3H-yohimbine in platelets, 3H-DHA in granulocytes, and 3H-spiperone in lymphocytes from healthy control persons, unmedicated (n = 28), and medicated (n = 8) schizophrenics, and from an unmedicated psychiatric control group (n = 14) were investigated. Furthermore, the actual concentration of the circulating CA was determined with HPLC-ECD. In unmedicated schizophrenics, as compared with controls, specific binding of 3H-spiperone to lymphocytes was markedly elevated in capacity and less in affinity. For beta 2 receptors a significant decrease was found in capacity with no change in affinity. The changes in alpha 2 receptors, viz. a slight decrease in capacity, were less distinct. The concentrations of circulating CA ranged from normal values to a more than threefold increase in NA and DA, whereas adrenaline (A) concentrations were nearly unchanged. No overall change in these data was found in the medicated schizophrenic patients. 3H-Spiperone binding was characteristically increased only in schizophrenics, but did not rise above control data in the nonschizophrenic psychiatric control group. Preliminary family studies suggest that this model could be valuable as a vulnerability marker.

Decreased levels of soluble intercellular adhesion molecule-1 (sICAM-1) in unmedicated and medicated schizophrenic patients.

BACKGROUND: The soluble intercellular adhesion molecule-1 (sICAM-1) is a marker for the activation of the cellular immune system. Since an activation of the immune system has been observed in a part of the schizophrenic patients, we measured the serum levels of soluble ICAM-1 (sICAM-1) in schizophrenic patients and correlated them to the patient's psychopathology. METHODS: To monitor a possible effect of antipsychotic therapy, 36 schizophrenic patients were examined twice: first without antipsychotic medication immediately after admission to the hospital and then, after clinical improvement before discharge. The results were compared with those of 36 age- and gender-related healthy individuals. RESULTS: The schizophrenic patients showed significantly decreased serum levels of sICAM-1 at the first examination (248 +/- 95 ng/mL) and at re-examination (266 +/- 95 ng/mL) compared with the comparison group (323 +/- 74 ng/mL). Patients with more pronounced negative symptoms showed higher levels of sICAM-1 at the first examination. CONCLUSIONS: We conclude that reduced sICAM-1 levels in schizophrenia indicate a reduced activity of the cellular immune system in at least a subgroup of schizophrenic patients.

Tardive dyskinesia: relation to computer-tomographic, endocrine, and psychopathological variables.

Severity of tardive dyskinesia (TD) and psychopathology of 36 chronic schizophrenic patients under long-term treatment with neuroleptics (NL) was rated during NL therapy and again 12 days after NL withdrawal. Both times serum levels of prolactin, norepinephrine, beta-endorphin, and cortisol were determined. In 27 of these patients ventricular-brain ratio, width of third ventricle, maximal width of anterior horns, distance between choroid plexus, and width of four largest sulci were also measured. Fifteen patients had no signs of TD; 14 had moderate, and 7 severe TD. TD was not related to age, age at onset of illness, duration of illness, dosage and type of neuroleptics, number of ECTs, or any endocrine variable. Psychopathology was barely related to TD, but after NL withdrawal, patients with TD tended to show more deterioration, particularly with regard to thought disorder and activation. With regard to computer-tomographic (CT) variables, patients without TD showed significantly less sulcal enlargement than those with TD. These results indicate that individual predisposition, which may have led to the development of TD, also seems to involve a higher risk of relapse after NL withdrawal.

Evidence against linkage of schizophrenia to chromosome 5q11-q13 markers in systematically ascertained families.

Ten pedigrees systematically ascertained in Germany were tested for linkage to chromosome 5q11-q13. In order to replicate the previous report by Sherrington et al (1988), families with a bipolar family member were omitted from the lod score calculations, all diagnoses were based upon Research Diagnostic Criteria, and four different models of the affection status were calculated, including the model for which Sherrington et al calculated the highest lod scores. None of the families investigated showed a positive lod score. Using multipoint linkage analyses, we were able to exclude the region for which a positive linkage has been reported.

Antibodies to heat shock proteins in schizophrenic patients: implications for the mechanism of the disease.

OBJECTIVE: The involvement of heat shock proteins has been determined in the pathophysiology of several disorders of the central nervous system, including multiple sclerosis. To elucidate their role in schizophrenia, the authors investigated antibody titers to heat shock proteins in unmedicated and medicated patients with schizophrenia. METHOD: Using the enzyme-linked immunosorbent assay technique, the authors measured titers of antibodies to 60 kilodaltons (kD) heat shock proteins (HSP60) and 70 kD heat shock proteins (HSP70) in 30 patients with schizophrenia before and during neuroleptic treatment and compared the titers with those of 31 healthy individuals. RESULTS: Ten (33%) of 30 patients with schizophrenia but only one (3%) of 31 healthy individuals showed immunoreactivity to HSP60 or HSP70. The authors found especially high anti-HSP70 titers in never-medicated patients. High anti-HSP60 titers were mainly found in patients who were being treated with neuroleptics. CONCLUSIONS: Since heat shock proteins are involved in diverse neuroprotective mechanisms, antibodies against heat shock proteins may inhibit neuroprotection. The authors discuss the implications of these findings for schizophrenia.

Increase in expression of adhesion molecule receptors on T helper cells during antipsychotic treatment and relationship to blood-brain barrier permeability in schizophrenia.

OBJECTIVE: The authors estimated the expression of adhesion molecule receptors (VLA-4 and LFA-1) on T helper (CD4+) and T suppressor/cytotoxic (CD8+) lymphocytes in schizophrenic patients before and during antipsychotic treatment and studied the relationship of these subpopulations to CSF measures and blood-brain barrier permeability. METHOD: Blood was drawn from hospitalized patients with schizophrenia before (N = 45) and after (N = 22) neuroleptic treatment and from an age-matched comparison group (N = 41). Lumbar punctures were performed on 32 of the schizophrenic patients. RESULTS: During antipsychotic treatment there were significant increases in the percentage of VLA-4+/CD4+ and VLA-4+/CD8+ cells. VLA-4+/CD4+ and LFA-1+/CD4+ cells were both closely related to disturbance of the blood-brain barrier. Higher values for VLA-4+/CD4+ and LFA-1+/CD4+ cells were found in patients with a disturbed blood-brain barrier. CONCLUSIONS: The findings suggest that adhesion molecules are involved in immunoregulation between the central nervous system and the peripheral immune system in schizophrenia.

Identification of dopamine D4 receptor mRNA in circulating human lymphocytes using nested polymerase chain reaction.

There is a long standing controversy if dopamine receptors are present on human lymphocytes. In recent years the expression of dopamine D3 and D5 receptors was demonstrated with molecular biological methods. Using reverse transcription and polymerase chain reaction (RT-PCR) we were able to demonstrate the expression of the dopamine D4 receptor (DRD4) mRNA in human circulating lymphocytes. Direct sequencing of the RT-PCR product assured that it corresponds to the human DRD4 sequence. However, because of the unusual high G/C content of the DRD4, several precautions have to be applied for reliable results.

Potential linkage for schizophrenia on chromosome 22q12-q13: a replication study.

In an attempt to replicate a potential linkage on chromosome 22q12-q13.1 reported by Pulver et al. [1994: Am J Med Genet 54:36-43], we have analyzed 4 microsatellite markers which span this chromosomal region, including the IL2RB locus, for linkage with schizophrenia in 30 families from Israel and Germany. Linkage analysis by pairwise lod score analysis as well as by multipoint analysis did not provide evidence for a single major gene locus. However, a lod score of Zmax = 0.612 was obtained for a dominant model of inheritance with the marker D22S304 at recombination fraction 0.2 by pairwise analysis. In addition, using a nonparametric method, sib pair analysis, a P value of 0.068 corresponding to a lod score of 0.48 was obtained for this marker. This finding, together with those of Pulver et al. [1994: Am J Med Genet 54:36-43] and Coon et al. [1994: Am J Med Genet 54:72-79], is suggestive of a genetic factor in this region, predisposing for schizophrenia in a subset of families. Further studies using nonparametric methods should be conducted in order to clarify this point.

Lack of association of serotonin-2A receptor gene polymorphism (T102C) with suicidal ideation and suicide.

Serotonergic dysfunction has been implicated in the pathophysiology of affective disorders and suicidality. Especially the density of the 5-HT2A receptor was claimed as being increased in suicidality, proposed as an adaptive upregulation due to reduced serotonergic transmission. Recent studies have shown an association of allele C of the 5-HT2A-T102C polymorphism with suicidal ideation in patients with major depression. The purpose of this study was to test whether this proposed marker indicates susceptibility not only to suicidal ideation in depressed patients but also to suicidality as a syndrome. We investigated the 5-HT2A-T102C polymorphism in 131 suicide victims with unknown underlying psychiatric diagnoses, 84 patients with major depression with or without suicidal ideation, and 125 healthy controls. We were unable to find any association of genotype or allele frequencies to major depression, suicidal ideation, or suicide as a syndrome. Thus, our results suggest that this polymorphism may not commonly be involved in the susceptibility to suicidality. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:831-835, 2000.

A European multicenter association study of HTR2A receptor polymorphism in bipolar affective disorder.

The available data on the role of 5-HT in a variety of behaviors support the hypothesis that a dysfunction in brain serotoninergic system activity contributes to vulnerability to major depression. The diversity in the electrophysiological actions of 5-HT in the central nervous system can now be categorized according to receptor subtypes and their respective effector mechanisms. In particular, the implication of central postsynaptic 5-HT2A receptor in affective disorders has been supported by findings consistent with the hypothesis of 5-HT2A receptor up-regulation in depression. For these reasons, the 5-HT2A receptor (HTR2A) gene can be considered as a candidate gene in bipolar affective disorder (BPAD). We tested the possible genetic contribution of the polymorphic DNA variation T102C in exon 1 of HTR2A (chromosome 13q14-21) gene in a large European multicentric case-control sample. Allele and genotype frequencies, as well as homo-heterozygote distributions were compared between the two groups of 309 bipolar affective disorder patients and 309 matched controls. No significant differences were observed in the allelic and genotypic (also for homo-heterozygote) distribution between BPAD and controls. These results indicate that, in our sample, the 5-HT2A receptor polymorphism studied is unlikely to play a major role in the genetic susceptibility to BPAD. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:136-140, 2000.

Tyrosine hydroxylase polymorphism and phenotypic heterogeneity in bipolar affective disorder: a multicenter association study.

Tyrosine hydroxylase (TH), the rate-limiting enzyme in the metabolism of catecholamines, is considered a candidate gene in bipolar affective disorder (BPAD) and has been the subject of numerous linkage and association studies. Taken together, most results do not support a major gene effect for the TH gene in BPAD. Genetic and phenotypic heterogeneity may partially explain the difficulty of confirming the exact role of this gene using both association and linkage methods. Four hundred one BPAD patients and 401 unrelated matched controls were recruited within a European collaborative project (BIOMED1 project in the area of brain research, European Community grant number CT 92-1217, project leader: J. Mendlewicz) involving 14 centers for a case-control association study with a tetranucleotide polymorphism in the TH gene. Patients and controls were carefully matched for geographical origin. Phenotypic heterogeneity was considered and subgroup analyses were performed with relevant variables: age at onset, family history, and diagnostic stability. No association was observed in the total sample or for subgroups according to age at onset (n = 172), family history alone (n = 159), or high degree of diagnostic stability and a positive family history (n = 131). The results of this association study do not confirm the possible implication of TH polymorphism in the susceptibility to BPAD.

The dependence of the clonidine growth hormone test on alcohol drinking habits and the menstrual cycle.

The dependence of the growth hormone (GH) response to clonidine (CLON) on alcohol drinking habits and on the menstrual cycle was investigated. GH response to CLON (0.15 mg i.v.) was blunted in 6 of 9 male, regularly beer-drinking non-depressed probands. After 14-17 and 30-37 days of abstinency, the probands showed a slight but not significant increase of the CLON stimulated GH maxima, and with great variability. During their menses, female probands had a significantly lower GH response to CLON than during ovulation. For these reasons, both alcohol drinking habits and, in females, the day of the menstrual cycle should be considered when the CLON-GH test is carried out in clinical studies.

Blunted growth hormone response to clonidine in Gilles de la Tourette syndrome.

Noradrenergic mechanisms have been involved in the pathogenesis of Gilles de la Tourette Syndrome (GTS). Since the central alpha 2 adrenergic agonist clonidine is widely used as a therapeutic agent in GTS, the present study aimed at assessing whether GH release after clonidine, representing central alpha 2-adrenergic receptor sensitivity, was altered in GTS. After administration of 2 micrograms/kg body weight clonidine, the GH response was examined in nine drug-free, alcohol-abstinent GTS patients (eight men, one woman) and in nine age- and sex-matched abstinent healthy controls. A blunted response of GH release (< 5 ng/ml) was observed in seven patients and the area under the curve (AUC) of the GH-release was significantly reduced (p < .01) compared to controls. This finding indicates an involvement of the noradrenergic system in GTS.

Clozapine--pharmacokinetic investigations and biochemical effects in man.

Clozapine with its unique pharmacological profile was investigated in different studies in order to elucidate its clinical-biochemical effects. Acute pharmacokinetic data showed a wide interindividual range with a mean halflife time of 6.0 h. The excretion pattern of catecholamines and their metabolites as well as hormone secretion were influenced in a different way. After 30 days of treatment, psychotic symptoms had markedly improved. However, only weak correlations were found to plasma levels. Side effects, such as sedation and orthostatic dysregulation, adapted and normalized during treatment. CSF-MHPG, CSF-5-HIAA decreased, CSF-HVA increased after 20 days of treatment indicating that the dopamine as well as the serotonin and noradrenaline systems are affected by Clozapine.

Changes in noradrenaline plasma levels and behavioural responses induced by benzodiazepine agonists with the benzodiazepine antagonist Ro 15-1788.

Noradrenaline (NA) plasma levels were examined in 18 healthy volunteers on 2 consecutive days after a single treatment with either lormetazepam (0.06 mg/kg) (LMZ group), flunitrazepam (0.03 mg/kg) (FNZ group) or placebo (PLA group) in combination with the benzodiazepine (BZ) antagonist Ro 15-1788 (0.1 mg/kg). Behavioural responses (mood changes, anxiety) were also investigated in parallel. Both BZ decreased NA plasma levels to 50% of the basal values 10 min after the injection; administration of Ro 15-1788 15 min later reinstated NA plasma levels to basal values. A second administration of Ro 15-1788 (0.1 mg/kg) 24 h after BZ or PLA treatment increased NA plasma levels, estimated 10 min after the injection in both the LMZ- and the FNZ groups, but not in the PLA group. Behavioural responses measured under the same treatment also indicated minor anxiety responses followed by mood impairment. These data suggest that a stressful situation may be precipitated by the antagonist Ro 15-1788 24 h after a single BZ treatment, which resembles a withdrawal response, and increases NA plasma levels.

Long-term neuroleptic treatment of chronic schizophrenic patients: clinical and biochemical effects of withdrawal.

In 17 chronic schizophrenic patients under chronic neuroleptic treatment for 13 years, a 30-day drug withdrawal resulted in early relapse of four patients, slight deterioration in five, and slight amelioration in eight patients. No incidence of neuroleptic symptoms such as tardive dyskinesia occurred. Prolactin in plasma and cerebrospinal fluid (CSF), not being elevated under chronic treatment, decreased significantly after 30 days of withdrawal. Homovanillic acid and 3-methoxy-4-hydroxyphenylglycol in CSF ranged normally and did not change during withdrawal. In contrast, plasma noradrenaline was elevated and decreased after drug discontinuation. No unequivocal relationship between biochemical and psychopathological features was found.

Neuroendocrine effects of clonidine in chronic schizophrenic patients under long-term neuroleptic therapy and after drug withdrawal: relations to psychopathology.

The sensitivity of the alpha-adrenergic hypothalamic pituitary system, as indicated by growth hormone (GH) release after clonidine (0.15 mg i.v.), was studied in nine chronic schizophrenic in-patients (study 1) under long-term neuroleptic (NL) therapy and after 5 days' drug withdrawal and in 17 chronic schizophrenic in-patients (study 2) under long-term NL therapy and after 12 days' drug withdrawal. GH response after 5- and 12-day drug-free periods did not differ significantly from that under NL treatment; however, it was significantly lower after 12 days' drug withdrawal (AUC: 319.9 +/- 445.5 ng/ml X min) compared to age- and sex-matched normal controls (579 +/- 611 ng/ml X min). The basal norepinephrine (NE) plasma levels under long-term NL therapy were significantly elevated in both studies (study 1:894 +/- 553 pg/ml; study 2:432 +/- 268 pg/ml) compared to controls (study 1:253 +/- 55 pg/ml, study 2:234 +/- 126 pg/ml), and were decreased significantly after 5 days' drug withdrawal compared to NL treatment. There was no significant correlation between age, duration of NL therapy, last daily dosage, psychopathology, and NE plasma levels and GH response. The data presented suggest hyposensitivity of alpha-adrenergic receptor function in the hypothalamic-pituitary axis after 12 days' drug withdrawal in chronic schizophrenics. The significantly elevated NE plasma levels under NL therapy indicate that there is no adaption mechanism, even after long-term treatment.

Neuroendocrine effects of apomorphine in chronic schizophrenic patients under long-term neuroleptic therapy and after drug withdrawal: relations to psychopathology and tardive dyskinesia.

The sensitivity of the dopaminergic hypothalamic pituitary system, as indicated by growth hormone (GH) release after apomorphine (0.5 mg SC), was studied in 11 chronic schizophrenic in-patients under long-term neuroleptic (NL) therapy and after 12 and 30 days' drug withdrawal. GH peak levels after a 12-day drug-free period were significantly elevated (13.1 +/- 12 ng/ml) as compared to NL therapy (4.6 +/- 6.1 ng/ml). Controls showed a significant higher mean peak GH response (13.6 +/- 10 ng/ml) compared to chronic schizophrenic patients under long-term NL therapy. The GH response of patients with symptoms of tardive dyskinesia (TD) did not differ significantly from that of patients without signs of TD. The prolactin (PRL) serum levels under long-term NL treatment were within the normal range in male schizophrenics but decreased significantly after 12 days' drug withdrawal. The data presented indicate a reduced sensitivity of the hypothalamic-pituitary dopamine receptors under long-term NL therapy. The significant increase in GH response on day 12 probably corresponds to a readjustment from a mostly blunted GH response under NL therapy back to stimulated levels of normal controls. No supersensitivity of the pituitary dopamine receptors could be detected.

Immunoglobulin and albumin content of cerebrospinal fluid in schizophrenic patients: relationship to negative symptomatology.

Alterations of the cerebrospinal fluid (CSF) protein contents and the blood brain barrier (BBB) in schizophrenia have been observed by several authors but no relationship to clinical characteristics like psychopathology, the course or the duration of the disease could be described until now. We have studied 27 schizophrenic patients upon each of whom a lumbar punction had been carried out for clinical reasons. The average values of the patients were within the normal range. Nine patients (33%) showed the total protein content to be > 45 mg% and 6 (22%) > 50 mg%. In the latter 6 patients an impaired BBB (raised albumin CSF/serum quotient) and in 4 patients (15%) a raised CSF immunoglobulin (IgG) were observed. No relation to the patient's age and the duration of the disease was found but correlations with the Scale for the Assessment of Negative Symptoms (SANS) showed significant results in the subscores "affective flattening/affective blunting", "alogia/paralogia" as well as in the total score with respect to the CSF contents of albumin and IgG (p = 0.009-0.02). These correlations suggest that the CSF albumin and the CSF IgG are related to the negative symptomatology in schizophrenia and that patients with these CSF alterations may have a higher risk of developing negative symptoms.