Methamphetamine (MA) use and MA-induced psychosis are associated with increasing aberrations in the compensatory immunoregulatory system, interleukin-1α, and CCL5 levels

There are only a few studies reporting on the immunological profiles of methamphetamine (MA) use, MA dependency, or MA-induced psychosis (MAP). This study measured M1 macrophage, T helper (Th)-1, Th-2, growth factor, and chemokine profiles, as well as the immune inflammatory response system (IRS) and compensatory immunoregulatory system (CIRS) in peripheral blood samples from patients with MA use (n = 51), MA dependence (n = 47), and MAP (n = 43) in comparison with controls (n = 32). We discovered that persistent MA use had a robust immunosuppressive impact on all immunological profiles. The most reliable biomarker profile of MA use is the combination of substantial CIRS suppression and a rise in selected pro-inflammatory cytokines, namely CCL27 (CTACK), CCL11 (eotaxin), and interleukin (IL)-1α. In addition, MA dependency is associated with increased immunosuppression, as demonstrated by lower stem cell factor levels and higher IL-10 levels. MAP is related to a significant decrease in all immunological profiles, particularly CIRS, and an increase in CCL5 (RANTES), IL-1α, and IL-12p70 signaling. In conclusion, long-term MA use and dependency severely undermine immune homeostasis, whereas MAP may be the consequence of increased IL-1α - CCL5 signaling superimposed on strongly depleted CIRS and Th-1 functions. The widespread immunosuppression established in longstanding MA use may increase the likelihood of infectious and immune illness or exacerbate disorders such as hepatitis and AIDS. Furthermore, elevated levels of CCL5, CCL11, CCL27, IL-1α, and/or IL-12p70 may play a role in the peripheral (atherosclerosis, cutaneous inflammation, immune aberrations, hypospermatogenesis) and central (neuroinflammation, neurotoxic, neurodegenerative, depression, anxiety, and psychosis) side effects of MA use.

A New Schizophrenia Model: Immune Activation is Associated with the Induction of Different Neurotoxic Products which Together Determine Memory Impairments and Schizophrenia Symptom Dimensions

Methods:

Serum levels of macrophage inflammatory protein-1 (MIP-1), soluble interleukin (IL)-1 receptor antagonist (sIL-1RA), IL-10, eotaxin, IgA/IgM responses to TRYCATs, and Consortium to Establish a Registry for Alzheimer’s disease (CERAD) tests were assessed in 40 controls and 80 schizophrenia patients.

Results:

Schizophrenia and MNP were predicted by significantly increased levels of IL-10, eotaxin and TRYCATs. A large part of variance in both PHEMN/DAPS symptom dimensions (42.8%) was explained by cytokine levels and TRYCATs combined. The MIP+sIL-1RA+IL-10 composite score and eotaxin explained each around on the basis of 19% of the variance in symptom dimensions, and approximately 18% of memory deficits. Moreover, MIP+sIL-1RA+IL-10 was significantly associated with elevations in picolinic acid, xanthurenic acid and 3-OH-kynurenine. Partial Least Squares path modeling shows that highly significant effects of MIP+sIL-1RA+IL-10 on symptomatology are mediated by the effects of noxious TRYCATs on memory deficits.

Conclusion:

Current findings indicate that in schizophrenia, immune activation may underpin activation of indoleamine-2,3-dioxygenase and kynurenine monooxygenase, while impairments in episodic and semantic memory may be caused by the neurotoxic effects of TRYCATs and eotaxin. The combined effects of immune activation, eotaxin and memory defects determine to a large extent, PHEMN/DAPS symptoms and the MNP phenotype. These findings indicate that schizophrenia phenomenology is largely mediated by multiple neuro-immune pathways and that immune activation, increased production of eotaxin and neurotoxic TRYCATs (picolinic acid, xanthurenic acid and 3-HOkynurenine) are new drug targets in schizophrenia and MNP.

Towards a new classification of stable phase schizophrenia into major and simple neuro-cognitive psychosis: Results of unsupervised machine learning analysis

RATIONALE

Deficit schizophrenia, as defined by the Schedule for Deficit Syndrome, may represent a distinct diagnostic class defined by neurocognitive impairments coupled with changes in IgA/IgM responses to tryptophan catabolites (TRYCATs). Adequate classifications should be based on supervised and unsupervised learning rather than on consensus criteria.

METHODS

This study used machine learning as means to provide a more accurate classification of patients with stable phase schizophrenia.

RESULTS

We found that using negative symptoms as discriminatory variables, schizophrenia patients may be divided into two distinct classes modelled by (A) impairments in IgA/IgM responses to noxious and generally more protective tryptophan catabolites, (B) impairments in episodic and semantic memory, paired associative learning and false memory creation, and (C) psychotic, excitation, hostility, mannerism, negative, and affective symptoms. The first cluster shows increased negative, psychotic, excitation, hostility, mannerism, depression and anxiety symptoms, and more neuroimmune and cognitive disorders and is therefore called "major neurocognitive psychosis" (MNP). The second cluster, called "simple neurocognitive psychosis" (SNP) is discriminated from normal controls by the same features although the impairments are less well developed than in MNP. The latter is additionally externally validated by lowered quality of life, body mass (reflecting a leptosome body type), and education (reflecting lower cognitive reserve).

CONCLUSIONS

Previous distinctions including "type 1" (positive)/"type 2" (negative) and DSM-IV-TR (eg, paranoid) schizophrenia could not be validated using machine learning techniques. Previous names of the illness, including schizophrenia, are not very adequate because they do not describe the features of the illness, namely, interrelated neuroimmune, cognitive, and clinical features. Stable-phase schizophrenia consists of 2 relevant qualitatively distinct categories or nosological entities with SNP being a less well-developed phenotype, while MNP is the full blown phenotype or core illness. Major neurocognitive psychosis and SNP should be added to the DSM-5 and incorporated into the Research Domain Criteria project.

Deficit schizophrenia is a discrete diagnostic category defined by neuro-immune and neurocognitive features: results of supervised machine learning

Deficit schizophrenia is characterized by neurocognitive impairments and changes in the patterning of IgA/IgM responses to plasma tryptophan catabolites (TRYCATs). In the current study, supervised pattern recognition methods, including logistic regression analysis (LRA), Support Vector Machine (SVM), and Soft Independent Modeling of Class Analogy (SIMCA), were used to examine whether deficit schizophrenia is a discrete diagnostic class with respect to Consortium To Establish a Registry for Alzheimer's disease (CERAD) and Cambridge Neuropsychological Test Automated Battery (CANTAB) tests and IgA/IgM responses to noxious (NOX) and generally more protective (PRO) TRYCATs. We recruited patients with (n = 40) and without (n = 40) deficit schizophrenia and healthy volunteers (n = 40). The combined use of TRYCAT and CERAD features strongly segregates deficit from nondeficit schizophrenia and healthy controls. Three out of the top five most important features in LRA, SVM and SIMCA agreed, namely two different NOX/PRO TRYCAT ratios and false memory recall. SIMCA shows that deficit schizophrenia is significantly separated from nondeficit schizophrenia and controls with as top 6 features IgA responses to picolinic acid, IgM responses to 3-OH-kynurenine and kynurenic acid, and impairments in Word List Memory and Verbal Fluency Tests and Mini-Mental State Examination. Nevertheless, nondeficit schizophrenia was not significantly separated from controls. The results show that schizophrenia is not a unitary disease with mere continuous differences in severity of illness between apparent subtypes. Deficit schizophrenia is a qualitatively distinct class defined by neuroimmune (autoimmune responses to TRYCATs) and neurocognitive (episodic and semantic memory) features coupled or not with clinical (negative) symptoms.

Eotaxin, an Endogenous Cognitive Deteriorating Chemokine (ECDC), Is a Major Contributor to Cognitive Decline in Normal People and to Executive, Memory, and Sustained Attention Deficits, Formal Thought Disorders, and Psychopathology in Schizophrenia Patients

Eotaxin is increased in neurodegenerative disorders and schizophrenia, and preclinical studies indicate that eotaxin may induce cognitive deficits. This study aims to examine whether peripheral levels of eotaxin impact cognitive functioning in healthy volunteers and formal thought disorder (FTD) and psychopathology in schizophrenia patients. Serum levels of eotaxin were assayed and cognitive tests were performed on a sample of 40 healthy participants and 80 schizophrenia patients. Among healthy participants, eotaxin levels were significantly associated with episodic/semantic memory, executive functions, Mini Mental State Examination, emotion recognition, and sustained attention. In addition, age-related effects on these cognitive measures were partly mediated by eotaxin. The super-variable "age-eotaxin" predicted a large part of the variance in cognitive functions among healthy participants, and hence, eotaxin may act as an "accelerated brain aging chemokine" (ABAC). In schizophrenia, eotaxin levels had a strong impact on formal thought disorders and psychopathology. In schizophrenia, increased eotaxin strongly impacts memory and sustained attention, which together to a large extent determine FTD. FTD together with memory deficits predicts around 92.5% of the variance in psychopathology. Moreover, the effects of eotaxin are partially mediated by executive functioning, while the effects of male sex on FTD and psychopathology are mediated by eotaxin. In healthy subjects, eotaxin strongly impacts executive functioning and multiple cognitive domains. In schizophrenia, peripheral levels of eotaxin strongly impact both negative symptoms and psychosis (hallucinations and delusions), and these eotaxin effects are mediated by impairments in frontal functioning, memory, sustained attention, and FTD. Eotaxin is an endogenous cognitive deteriorating chemokine (ECDC) and a novel therapeutic target for age-related cognitive decline and schizophrenia as well.

In Schizophrenia, Depression, Anxiety, and Physiosomatic Symptoms Are Strongly Related to Psychotic Symptoms and Excitation, Impairments in Episodic Memory, and Increased Production of Neurotoxic Tryptophan Catabolites: a Multivariate and Machine Learning Study

The depression, anxiety and physiosomatic symptoms (DAPS) of schizophrenia are associated with negative symptoms and changes in tryptophan catabolite (TRYCAT) patterning. The aim of this study is to delineate the associations between DAPS and psychosis, hostility, excitation, and mannerism (PHEM) symptoms, cognitive tests as measured using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) and IgA/IgM responses to TRYCATs. We included 40 healthy controls and 80 participants with schizophrenia. Depression and anxiety symptoms were measured with The Hamilton Depression (HAM-D) and Anxiety (HAM-A) Rating Scales, respectively. Physiosomatic symptoms were assessed with the Fibromyalgia and Chronic Fatigue Syndrome Rating Scale (FF). Negative symptoms as well as CERAD tests, including Verbal Fluency Test (VFT), Mini-Mental State Examination (MMSE), Word List Memory (WLM), and WL Delayed Recall were measured, while ratios of IgA responses to noxious/protective TRYCATs (IgA NOX_PRO) were computed. Schizophrenia symptoms consisted of two dimensions, a first comprising PHEM and negative symptoms, and a second DAPS symptoms. A large part of the variance in DAPS was explained by psychotic symptoms and WLM. Of the variance in HAM-D, 58.9% was explained by the regression on excitement, IgA NOX_PRO ratio, WLM, and VFT; 29.9% of the variance in HAM-A by psychotic symptoms and IgA NOX/PRO; and 45.5% of the variance in FF score by psychotic symptoms, IgA NOX/PRO, and WLM. Neural network modeling shows that PHEM, IgA NOX_PRO, WLM, and MMSE are the dominant variables predicting DAPS. DAPS appear to be driven by PHEM and negative symptoms coupled with impairments in episodic memory, especially false memory creation, while all symptom dimension and cognitive impairments may be driven by an increased production of noxious TRYCATs, including picolinic, quinolinic, and xanthurenic acid.

Affective symptoms in schizophrenia are strongly associated with neurocognitive deficits indicating disorders in executive functions, visual memory, attention and social cognition

The aim of this study was to assess the neurocognitive correlates of affective symptoms in schizophrenia. Towards this end, 40 healthy controls and 80 schizophrenia patients were investigated with six tests of the Cambridge Neuropsychological Test Automated Battery (CANTAB), assessing spatial working memory, paired-association learning, one touch stocking, rapid visual information (RVP), emotional recognition test and intra/extradimensional set shifting. The Hamilton Depression (HDRS) and Anxiety (HAMA) Rating Scales and the Calgary Depression Scale for Schizophrenia (CDSS) as well as the Positive and Negative Syndrome Scale (PANSS) were also used. There were highly significant associations between all 6 CANTAB tests and HDRS, HAMA and CDSS (except RVP) scores. The most significant items associating with neurocognitive impairments in schizophrenia were self-depreciation (CDSS), fatigue, psychomotor retardation and agitation, psychic and somatic anxiety (HDRS), fears, cognitive symptoms, somatic-muscular, genito-urinary and autonomic symptoms and anxious behavior (HAMA). The selected HDRS and HAMA symptoms indicate fatigue, fears, anxiety, agitation, retardation, somatization and subjective cognitive complaints (SCC) and are therefore labeled "FAARS". Up to 28.8% of the variance in the 6 CANTAB measurements was explained by FAARS, which are better predictors of neurocognitive impairments than the PANSS negative subscale score. Neurocognitive deficits in schizophrenia are best predicted by FAARS combined with difficulties in abstract thinking. In conclusion, depression and anxiety symptoms accompanying the negative and positive symptoms of schizophrenia are associated with neurocognitive deficits indicating disorders in executive functions, attention, visual memory, and social cognition. Neurocognitive deficits in schizophrenia reflect difficulties in abstract thinking and FAARS, including subjective cognitive complaints.

Physio-somatic symptoms in schizophrenia: association with depression, anxiety, neurocognitive deficits and the tryptophan catabolite pathway

To investigate the frequency of physio-somatic symptoms (PS) symptoms in schizophrenia and their relation to positive, negative and affective symptoms; neurocognitive deficits and impairments in the tryptophan catabolite (TRYCAT) pathway. Eighty four patients with schizophrenia and 40 healthy controls were assessed using the 12 item Fibromyalgia and Chronic Fatigue Syndrome Rating scale (FF) and scales for negative and positive symptoms, depression and anxiety. Cognitive functioning was tested using the Cambridge Neuropsychological Test Automated Battery (CANTAB). Other assessments included: immunoglobulin (Ig)A and IgM responses to tryptophan catabolites (TRYCATs), namely quinolinic (QA), 3-OH-kynurenine (3HK), picolinic (PA), xanthurenic (XA) and kynurenic acid (KA) and anthranilic acid (AA). More than 50% of the patients studied had elevated levels of physio-somatic (PS) symptoms, significantly co-occurring with depression and anxiety, but not with negative or positive symptoms. PS symptoms were significantly associated with IgA/IgM responses to TRYCATs, including increased IgA responses to 3 HK, PA and XA, and lowered IgA to QA and AA. Fatigue, muscle pain and tension, autonomic and cognitive symptoms and a flu-like malaise were strongly associated with cognitive impairments in spatial planning and working memory, paired associative learning, visual sustained attention and attention set shifting. PS symptoms in schizophrenia aggregate with depression and anxiety symptoms and may be driven by TRYCAT patterning of IgA/IgM-responses, with IgA indicating mucosal-mediated changes and IgM indicating regulatory functions. As such, the patterning of IgA/IgM responses to TRYCATs may indicate differential TRYCATs regulation of neuronal and glia activity that act to regulate PS signalling in schizophrenia.