Immunological influences in attention-deficit disorder and schizophrenia; is there a link between these two conditions?

Schizophrenia: a pathogenetic autoimmune disease caused by viruses and pathogens and dependent on genes

Many genes have been implicated in schizophrenia as have viral prenatal or adult infections and toxoplasmosis or Lyme disease. Several autoantigens also target key pathology-related proteins. These factors are interrelated. Susceptibility genes encode for proteins homologous to those of the pathogens while the autoantigens are homologous to pathogens' proteins, suggesting that the risk-promoting effects of genes and risk factors are conditional upon each other, and dependent upon protein matching between pathogen and susceptibility gene products. Pathogens' proteins may act as dummy ligands, decoy receptors, or via interactome interference. Many such proteins are immunogenic suggesting that antibody mediated knockdown of multiple schizophrenia gene products could contribute to the disease, explaining the immune activation in the brain and lymphocytes in schizophrenia, and the preponderance of immune-related gene variants in the schizophrenia genome. Schizophrenia may thus be a “pathogenetic” autoimmune disorder, caused by pathogens, genes, and the immune system acting together, and perhaps preventable by pathogen elimination, or curable by the removal of culpable antibodies and antigens.

Chain reaction or time bomb: a neuropsychiatric-developmental/neurodevelopmental formulation of tourettisms, pervasive developmental disorder, and schizophreniform symptomatology associated with PANDAS

We present the case of a boy who over time sequentially exhibited symptoms consistent with a pervasive developmental disorder, schizophreniform symptomatology, multiple motor and vocal tics, and myoclonus. During this period he experienced multiple episodes of group A beta-haemolytic streptococcal (strep) infection confirmed by culture and serological studies. We speculate that paediatric autoimmune neuropsychiatric disorder associated with strep (PANDAS) may have served as an element in a complex chain of causation influencing the expression of his symptoms. Our main emphasis is to utilize our case study as an example of the application in case formulation of the neuropsychiatric developmental model and of the neurodevelopmental model on symptom ontogenesis and clinical outcome.

Signal transducer and activator of transcription 6 (STAT6) and attention-deficit hyperactivity disorder: A speculative hypothesis

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by hyperactivity, impulsiveness and inattention that begins in childhood. The underlying pathogenesis of this disorder is still unknown, although pharmacological, genetic and neuroimaging studies suggest that dopamine transportation may be implicated in the pathogenesis of ADHD. Signal transducer and activator of transcription 6 (STAT6), similar to other members of the signal transducer and activator of transcription family of proteins, is an important molecule in the induction and regulation of the immune response. Animal studies have demonstrated that STAT6 is highly expressed in the CNS, especially in the developing brain. Recent studies have demonstrated that STAT6-deficient mice exhibit increased locomotor activity and decreased levels of dopamine transporter expression in the striatum, when compared with the wild-type. From these findings, and evidence from other studies, it can be proposed that STAT6 may be implicated in the pathogenesis of ADHD. Several proposals to test this hypothesis are suggested; attempts to prove the STAT6-ADHD hypothesis may provide a new direction that elucidates the pathogenesis of and a treatment for ADHD.

Antibodies against astrocyte M1and M2muscarinic cholinoceptor from schizophrenic patients' sera

We demonstrated the presence of circulating antibodies from schizophrenic patients able to interact with cultured astrocytes activating muscarinic acetylcholine receptors (mAChRs). Sera and purified IgG from 15 paranoid schizophrenic and 15 age-matched normal subjects were studied by indirect immunofluorescence (IFI), flow cytometry, dot blot, enzyme immunoassay (ELISA), and radioligand competition assays. Astrocyte membranes and/or a synthetic peptide, with identical amino acid sequence of human M(1) and M(2) mAChR, were used as antigens. By IFI and flow cytometry procedures, we proved that serum purified IgG fraction from schizophrenic patients, reacted to astrocyte cell surface. The same antibodies were able to inhibit the binding of the specific mAChR radioligand (3)H-QNB. Using synthetic peptide for dot blot and ELISA, we demonstrated that these antibodies reacted against the second extracellular loop of human cerebral M(1) and M(2) mAChR. Also, the corresponding affinity-purified antipeptide antibody displayed an agonistic-like activity associated to specific M(1) and M(2) mAChR activation, increasing inositol phosphates accumulation and decreasing cyclic AMP production, respectively. This article gives support to the participation of an autoimmune process in schizophrenia disease.

The role of tumor necrosis factor-alpha in the pathogenesis of anorexia and bulimia nervosa, cancer cachexia and obesity

In this paper a new immunological model of anorexia and bulimia nervosa will be presented in which the inflammatory cytokines are conceived as the fundamental regulators of body metabolism. This conception differs from the conventional view in which the inflammatory cytokines are perceived primarily as peptide molecules utilized by the immune system to control infection, inflammation and tissue or neuronal damage. Given that the inflammatory cytokines are also fundamental regulators of body metabolism, when they become dysregulated they create physiological chaos which results in the development of a number of autoimmune, metabolic and psychiatric disorders. In this proposed immunological model of anorexia and bulimia nervosa, elevated tumor necrosis factor-alpha features as the primary cause of these conditions. Pathophysiological parallels are drawn between anorexia nervosa and cancer cachexia in terms of the causal role the cytokines, neuropeptides and neurotransmitters play in the manifestation of shared symptoms. These shared symptoms include elevated tumour necrosis factor-alpha, down-regulated interleukin-2 and interleukin-4 and depletion of lean body mass. Furthermore, the following neuropeptides are dysregulated in both anorexia nervosa and cancer cachexia: vasoactive intestinal peptide, cholecystokinin, corticotropin-releasing factor, neuropeptide Y, peptide YY and beta-endorphin. In addition, in anorexia and bulimia nervosa, secretion of the neurotransmitter serotonin is inhibited while norepinephrine is enhanced. It will be argued that the causal interplay between the cytokines, neuropeptides and neurotransmitters initiates a cascade of biochemical events which may result in either anorexia or bulimia nervosa, or cancer cachexia. The extent to which these inflammatory cytokines, neuropeptides and neurotransmitters are causally efficacious in the pathogenesis of other autoimmune disorders, such as diabetes mellitus and rheumatoid arthritis, will also be addressed.