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Attention is one of the cognitive domains typically affected in multiple sclerosis. The Attention Network Test was developed to measure the function of the three distinct attentional networks, alerting, orienting, and executive control. The Attention Network Test has been performed in various neuropsychiatric conditions, but not in multiple sclerosis. Our objective was to investigate functions of attentional networks in multiple sclerosis by means of the Attention Network Test. Patients with relapsing-remitting multiple sclerosis (n = 57) and healthy controls (n = 57) matched for age, sex, and education performed the Attention Network Test. Significant differences between patients and controls were detected in the alerting network (p = 0.003), in contrast to the orienting (p = 0.696) and the conflict (p = 0.114) network of visual attention. Mean reaction time in the Attention Network Test was significantly longer in multiple sclerosis patients than in controls (p = 0.032), Multiple sclerosis patients benefited less from alerting cues for conflict resolution compared with healthy controls. The Attention Network Test revealed specific alterations of the attention network in multiple sclerosis patients which were not explained by an overall cognitive slowing.

The results contribute to the accumulating evidence for an association of the X-chromosomal HTR2C gene with antipsychotic-induced BWG. The proposed underlying mechanisms include decreased HTR2C gene expression with reduced 5-HT-modulated activation of hypothalamic proopiomelanocortin-neurons, and inverse 5-HT(2C) agonism in the presence of D(2) receptor antagonism.

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Clozapine-induced agranulocytosis (CA) is still among the least understood adverse drug reactions in psychopharmacology. In particular, its genetic background is far from being clarified. Within the framework of a casecontrol study, we performed human leukocyte antigen (HLA) genotyping and haplotype analyses in 42 non-Jewish Caucasian schizophrenic patients (N ¼ 42) suffering from CA and 75 non-Jewish Caucasian schizophrenic patients treated with clozapine without developing CA. While controlling for age (Po0.0001) and sex (P ¼ 0.835), testing of the alleles from both HLA-loci resulted in borderline results for Cw2 (P ¼ 0.085, odds ratio (OR) ¼ 0.36, 95% confidence interval (CI): 0.08-1.23), Cw7 (P ¼ 0.058, OR ¼ 2.0, 95% CI: 0.87-4.63) and DRB5*0201 (P ¼ 0.005, adjusted OR ¼ 22.15). For haplotype analysis, we obtained significant association results with CA for the two-locus haplotypes HLA-Cw-B (P ¼ 0.022) and HLA-DRB5-DRB4 (P ¼ 0.050), and for the three-locus haplotype HLA-Cw-B-DRB5 (P ¼ 0.030). The complex nature of CA implies that many genes might play a role, but currently, only HLA associations with CA are identified as clinically relevant.

Clozapine-induced agranulocytosis (CiA) is a potentially life-threatening pharmacological adverse drug reaction, which limits a broader application of this highly effective atypical antipsychotic in schizophrenic patients. Although this adverse reaction has been well known for almost 30 years, only few genetically based determinants can be identified to date. Furthermore, owing to rare occurrence, specific clinical course and complexity of pathomechanisms of antipsychotic-induced agranulocytosis, only a few of the findings met the criteria of replication. The most promising susceptibility genes for CiA include genes involved in the human leukocyte antigen system and in specific metabolizing enzyme systems. However, complex idiosyncratic drug reactions such as CiA are considered to be determined by multiple, possibly interacting genetic variations, rather than by a single causative variant.

Our data suggest a disease-related dissociation of executive attention with reduced conflict effects in SZP. Furthermore, they support the hypothesis of differential tonic-phasic dopamine activation and specific dopamine level effects in different cognitive tasks, which helps interpreting contradictory findings of Met allele load on cognitive performance. Disease status seems to modulate the impact of COMT Val108/158Met on cognitive performance.

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