Immunological causes of obsessive-compulsive disorder: is it time for the concept of an "autoimmune OCD" subtype?

Obsessive-compulsive disorder (OCD) is a highly disabling mental illness that can be divided into frequent primary and rarer organic secondary forms. Its association with secondary autoimmune triggers was introduced through the discovery of Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal infection (PANDAS) and Pediatric Acute onset Neuropsychiatric Syndrome (PANS). Autoimmune encephalitis and systemic autoimmune diseases or other autoimmune brain diseases, such as multiple sclerosis, have also been reported to sometimes present with obsessive-compulsive symptoms (OCS). Subgroups of patients with OCD show elevated proinflammatory cytokines and autoantibodies against targets that include the basal ganglia. In this conceptual review paper, the clinical manifestations, pathophysiological considerations, diagnostic investigations, and treatment approaches of immune-related secondary OCD are summarized. The novel concept of "autoimmune OCD" is proposed for a small subgroup of OCD patients, and clinical signs based on the PANDAS/PANS criteria and from recent experience with autoimmune encephalitis and autoimmune psychosis are suggested. Red flag signs for "autoimmune OCD" could include (sub)acute onset, unusual age of onset, atypical presentation of OCS with neuropsychiatric features (e.g., disproportionate cognitive deficits) or accompanying neurological symptoms (e.g., movement disorders), autonomic dysfunction, treatment resistance, associations of symptom onset with infections such as group A streptococcus, comorbid autoimmune diseases or malignancies. Clinical investigations may also reveal alterations such as increased levels of anti-basal ganglia or dopamine receptor antibodies or inflammatory changes in the basal ganglia in neuroimaging. Based on these red flag signs, the criteria for a possible, probable, and definite autoimmune OCD subtype are proposed.

Autoantibody-associated psychiatric syndromes: a systematic literature review resulting in 145 cases.

BACKGROUND: Autoimmune encephalitis (AE) is an important consideration during the diagnostic work-up of secondary mental disorders. Indeed, isolated psychiatric syndromes have been described in case reports of patients with underlying AE. Therefore, the authors performed a systematic literature review of published cases with AE that have predominant psychiatric/neurocognitive manifestations. The aim of this paper is to present the clinical characteristics of these patients. METHODS: The authors conducted a systematic Medline search via Ovid, looking for case reports/series of AEs with antineuronal autoantibodies (Abs) against cell surface/intracellular antigens combined with predominant psychiatric/neurocognitive syndromes. The same was done for patients with Hashimoto encephalopathy/SREAT. Only patients with signs of immunological brain involvement or tumors in their diagnostic investigations or improvement under immunomodulatory drugs were included. RESULTS: We identified 145 patients with AE mimicking predominant psychiatric/neurocognitive syndromes. Of these cases, 64% were female, and the mean age among all patients was 43.9 (±22.1) years. Most of the patients had Abs against neuronal cell surface antigens (55%), most frequently against the NMDA-receptor (N = 46). Amnestic/dementia-like (39%) and schizophreniform (34%) syndromes were the most frequently reported. Cerebrospinal fluid changes were found in 78%, electroencephalography abnormalities in 61%, and magnetic resonance imaging pathologies in 51% of the patients. Immunomodulatory treatment was performed in 87% of the cases, and 94% of the patients responded to treatment. CONCLUSIONS: Our findings indicate that AEs can mimic predominant psychiatric and neurocognitive disorders, such as schizophreniform psychoses or neurodegenerative dementia, and that affected patients can be treated successfully with immunomodulatory drugs.

Spreading of acute myeloid leukemia cells by trafficking along the peripheral outflow pathway of cerebrospinal fluid.

Acute myeloid leukemia (AML) can affect not only bone marrow (BM) and peripheral blood (PB), but also the compartment of cerebrospinal fluid (CSF). Besides standard chemotherapy, specific and non-specific immunotherapy has been employed synergistically to treat AML patients. Here we report on a patient who received standard chemotherapy, unspecific immunotherapy with interleukin-2, as well as later specific CD8+ T-cell stimulation by RHAMM-R3 peptide vaccination. The patient maintained a complete remission in BM and PB, while he developed recurrent relapses in the CSF. Moreover, the patient developed a chloroma in the vicinity of neuronal sheaths during hematological CR, but high leukemia cell numbers within the CSF spaces over a long time period. This rare observation demonstrates several aspects. There is a previously unknown site of leukemia cell distribution, namely the peripheral cerebrospinal outflow pathway (PCOP). This demonstrates the ineffective therapy of this previously unknown mechanism of leukemia cell spread. The hypothesis that the PCOP is a site of physiological CSF-T-cell trafficking, and the lumen of the PCOP should be considered as an extension of the subarachnoidal spaces without closed anatomical borders is supported by this observation. The CSF spaces, but possibly specifically the PCOP, may represent a previously unknown survival niche of tumor cells within intrathecal spaces.

Personality disorders improved after arachnoid cyst neurosurgery, then rediagnosed as 'minor' organic personality disorders.

The prevalence of arachnoid cysts (AC) is considerably increased in psychiatric patients, suggesting a possible causal relationship between AC and certain psychiatric disorders. Neurosurgery of AC in psychiatric disorders is, however, not recommended if no accompanying neurological symptoms or signs of increased intracranial pressure are present. In two cases of slow onset personality disorder in persons suffering from so-called asymptomatic AC, we performed AC neurosurgery beyond established rules. Both comparisons before and after neurosurgery of psychopathology and the following long-term course support in retrospect that both cases might be re-diagnosed as having suffered from 'minor' organic personality disorders before AC neurosurgery, which improved thereafter. The two cases did not initially appear to fulfill the established criteria for organic personality disorders either according to ICD-10 or DSM-IV, but in retrospect satisfied most criteria. In themselves, the personality disorders appeared not very severe, but had considerable relevance for the patients' lives. The established rules for AC neurosurgery should be reconsidered at least when therapy-resistant psychiatric disorders are observed in AC sufferers.

Flow cytometric analysis of T cell subsets in paired samples of cerebrospinal fluid and peripheral blood from patients with neurological and psychiatric disorders.

Recent studies suggest inflammatory mechanisms involved in the pathogenesis of major psychiatric disorders (MPD). T cells play a major role during inflammation, but little is known about T cell subpopulations in the cerebrospinal fluid (CSF). We investigated the frequency of cells positive for the surface markers CD4, CD8, CD25, CD45, CD69, and CD127 in 45 paired cerebrospinal fluid (CSF) and peripheral blood (PB) samples by multiparameter flow cytometry from patients with MPD of the schizophrenic and affective spectrum with normal CSF cell counts and compared them with those from patients with non-inflammatory (NIND), chronic inflammatory (CIND) neurological disorders, and meningitis (MEN). In MEN patients, CD4+ cell frequency in PB, but not in CSF, was significantly increased as compared to CIND and NIND. No difference between patient groups was observed for CD8+. CD4+CD45RO+ double positive cells in PB were significantly lower in CIND than in MEN or NIND. The frequency of CD4+CD25+ cells in PB was significantly higher in MEN than in MPD or CIND. For CSF, the percentage of CD4+CD127(dim) cells was significantly lower in MEN than in MPD. CD4+CD127(dim) in PB and CSF showed overlapping characteristic clusters between MPD and CIND and MEN patients. Overall, the hypothesis of low degree inflammation in a subgroup of MPD is supported. The analysis of lymphocyte subsets in PB and CSF constitutes a novel promising tool to understand underlying pathomechanisms in psychiatric and neurological disorders on an individual case level.