BACKGROUND: Stable-phase schizophrenia may comprise two distinct nosological entities namely Major Neuro-Cognitive Psychosis (MNP, largely overlapping with the deficit syndrome) and simple NP (SNP), which are defined by neuroimmune and neurocognitive abnormalities. Furthermore, cognitive impairments and PHEM (psychotic, hostility, excitation, mannerism) and negative symptoms load on the same dimension.METHODS: The current study aimed to investigate associations of psychomotor retardation (PMR) and clinical as well as biomarker characteristics of schizophrenia. We recruited 40 healthy controls and 79 schizophrenia patients and measured IgA responses to tryptophan catabolites (TRYCATs), IgM to malondialdehyde and nitroso (NO)-cysteinyl, macrophage inflammatory protein-1 (MIP-1), soluble interleukin (IL)-1 receptor antagonist (sIL-1RA), IL-10, CCL-11 as well as PMR items of different rating scales and motor screening task (MOT). RESULTS: PMR differentiated schizophrenia from controls and MNP from SNP. In addition, PMR was strongly associated with executive functions, deficits in episodic and semantic memory, PHEM and negative (PHEMN) symptoms. Around 50% of the variance in PMR was predicted by the cumulative effects of immune activation, CCL-11, TRYCATs and NO-Cysteinyl levels, and lowered natural IgM. PRM may be reliably combined with PHEMN symptoms and memory and executive impairments into one latent vector reflecting overall psychopathology.CONCLUSIONS: Current findings indicate that PMR may be a key psychopathological feature of schizophrenia and mainly MNP. In addition, PMR and associated impairments in memory and executive functions, and PHEMN symptoms may be driven by deficits in the compensatory immune regulatory system (natural IgM) combined with increased production of neurotoxic immune products, namely TRYCATs and IgM to NO-cysteinyl, and an endogenous cognition deteriorating chemokine, namely CCL-11.