Does treating schizophrenia reduce the chances of developing amyotrophic lateral sclerosis?

Subacute combined degeneration of the spinal cord masking motor neuron disease: a case report

Background

Subacute combined degeneration of the spinal cord is a potentially reversible myelopathy typically associated with vitamin B12 deficiency. There is predominant involvement of spinal cord posterior and lateral tracts, and manifestations include peripheral paraesthesia, impaired proprioception, gait disturbance, neuropathy and cognitive changes. Motor neuron disease (MND) is an unremittingly progressive neurodegenerative disorder involving upper and lower motor neurons with an average prognosis of 2–3 years. The diagnosis is clinical and may be supported by electromyography. A subset of MND occurs concurrently with frontotemporal dementia (FTD-MND) and may be initially misdiagnosed as a primary psychotic disorder.

Case presentation

We describe a 57-year-old Caucasian woman who presented with confusion and dysarthria. Low vitamin B12 levels and MRI findings led to an initial diagnosis of subacute combined degeneration of the spinal cord. Despite treatment, persistent dysarthria and presence of both upper and lower motor neuron signs on clinical examination prompted further assessment. Electromyography supported the diagnosis of MND. Comorbid chronic paranoid schizophrenia complicated the diagnostic process. We discuss overlapping features between B12 deficiency and MND as well as the neuropsychiatric overlap of B12 deficiency, FTD-MND and chronic schizophrenia.

Conclusions

Firstly, variability in neurocognitive and imaging manifestations of B12 deficiency can limit delineation of other pathologies. Failure to improve following correction of nutritional deficiencies warrants further investigation for an alternate diagnosis. Secondly, re-evaluation of patients with comorbid mental health conditions is important in reaching timely and accurate diagnoses.

Pathomechanisms of Blood-Brain Barrier Disruption in ALS

The blood-brain barrier (BBB) and the blood-spinal cord barrier (BSCB) are responsible for controlling the microenvironment within neural tissues in humans. These barriers are fundamental to all neurological processes as they provide the extreme nutritional demands of neural tissue, remove wastes, and maintain immune privileged status. Being a semipermeable membrane, both the BBB and BSCB allow the diffusion of certain molecules, whilst restricting others. In amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases, these barriers become hyperpermeable, allowing a wider variety of molecules to pass through leading to more severe and more rapidly progressing disease. The intention of this review is to discuss evidence that BBB hyperpermeability is potentially a disease driving feature in ALS and other neurodegenerative diseases. The various biochemical, physiological, and genomic factors that can influence BBB permeability in ALS and other neurodegenerative diseases are also discussed, in addition to novel therapeutic strategies centred upon the BBB.

Neuroleptics as therapeutic compounds stabilizing neuromuscular transmission in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing, fatal disorder with no effective treatment. We used simple genetic models of ALS to screen phenotypically for potential therapeutic compounds. We screened libraries of compounds in C. elegans, validated hits in zebrafish, and tested the most potent molecule in mice and in a small clinical trial. We identified a class of neuroleptics that restored motility in C. elegans and in zebrafish, and the most potent was pimozide, which blocked T-type Ca2+ channels in these simple models and stabilized neuromuscular transmission in zebrafish and enhanced it in mice. Finally, a short randomized controlled trial of sporadic ALS subjects demonstrated stabilization of motility and evidence of target engagement at the neuromuscular junction. Simple genetic models are, thus, useful in identifying promising compounds for the treatment of ALS, such as neuroleptics, which may stabilize neuromuscular transmission and prolong survival in this disease.

Genetic correlation between amyotrophic lateral sclerosis and schizophrenia

We have previously shown higher-than-expected rates of schizophrenia in relatives of patients with amyotrophic lateral sclerosis (ALS), suggesting an aetiological relationship between the diseases. Here, we investigate the genetic relationship between ALS and schizophrenia using genome-wide association study data from over 100,000 unique individuals. Using linkage disequilibrium score regression, we estimate the genetic correlation between ALS and schizophrenia to be 14.3% (7.05-21.6; P=1 × 10-4) with schizophrenia polygenic risk scores explaining up to 0.12% of the variance in ALS (P=8.4 × 10-7). A modest increase in comorbidity of ALS and schizophrenia is expected given these findings (odds ratio 1.08-1.26) but this would require very large studies to observe epidemiologically. We identify five potential novel ALS-associated loci using conditional false discovery rate analysis. It is likely that shared neurobiological mechanisms between these two disorders will engender novel hypotheses in future preclinical and clinical studies.

Cooccurrences of Putative Endogenous Retrovirus-Associated Diseases

At least 8% of the human genome is composed of endogenous retrovirus (ERV) sequences. ERVs play a role in placental morphogenesis and can sometimes protect the host against exogenous viruses. On the other hand, ERV reactivation has been found to be associated with different diseases, for example, multiple sclerosis (MS), schizophrenia, type 1 diabetes mellitus (T1D), or amyotrophic lateral sclerosis (ALS). Little is known about the cooccurrence of these diseases. If all these diseases are caused by ERV, antiretroviral therapy should perhaps also show some effects in the other diseases. Here, we summarize literature demonstrating that some ERV-associated diseases seem to appear together more often than expected, for example, MS and ALS, MS and T1D, MS and schizophrenia, or ALS and T1D. In contrast, some ERV-associated diseases seem to appear together less frequently than expected, for example, schizophrenia and T1D. Besides, some reports demonstrate amelioration of MS, ALS, or schizophrenia under antiretroviral therapy in human immunodeficiency virus-infected patients. If such results could be confirmed in larger studies, alternative therapy strategies for ERV-associated diseases like MS and schizophrenia might be possible.

NAP (davunetide) modifies disease progression in a mouse model of severe neurodegeneration: protection against impairments in axonal transport

NAP (davunetide) is a novel neuroprotective compound with mechanism of action that appears to involve microtubule (MT) stabilization and repair. To evaluate, for the first time, the impact of NAP on axonal transport in vivo and to translate it to neuroprotection in a severe neurodegeneration, the SOD1-G93A mouse model for amyotrophic lateral sclerosis (ALS) was used. Manganese-enhanced magnetic resonance imaging (MRI), estimating axonal transport rates, revealed a significant reduction of the anterograde axonal transport in the ALS mice compared to healthy control mice. Acute NAP treatment normalized axonal transport rates in these ALS mice. Tau hyperphosphorylation, associated with MT dysfunction and defective axonal transport, was discovered in the brains of the ALS mice and was significantly reduced by chronic NAP treatment. Furthermore, in healthy wild type (WT) mice, NAP reversed axonal transport disruption by colchicine, suggesting drug-dependent protection against axonal transport impairment through stabilization of the neuronal MT network. Histochemical analysis showed that chronic NAP treatment significantly protected spinal cord motor neurons against ALS-like pathology. Sequential MRI measurements, correlating brain structure with ALS disease progression, revealed a significant damage to the ventral tegmental area (VTA), indicative of impairments to the dopaminergic pathways relative to healthy controls. Chronic daily NAP treatment of the SOD1-G93A mice, initiated close to disease onset, delayed degeneration of the trigeminal, facial and hypoglossal motor nuclei as was significantly apparent at days 90-100 and further protected the VTA throughout life. Importantly, protection of the VTA was significantly correlated with longevity and overall, NAP treatment significantly prolonged life span in the ALS mice.

Microparticles and microscopic structures in three fractions of fresh cerebrospinal fluid in schizophrenia: case report of twins

Schizophrenia is a diagnosis with a set of symptoms of aberrant psychological phenomena. Here, we discuss that there may be an imbalance of proteostasis of neurons in the brain leading to increase in membrane shedding and buildup of microparticles (MPs) appearing in the cerebrospinal fluid. The number of MPs can be determined and their phenotypes verified by size and membrane expression with flow cytometry. This is the first report of specified MPs in cerebrospinal fluid (CSF) in schizophrenia. Two 56-year-old Swedish-born female monozygotic twins of Caucasian ethnicity with onset of schizophrenia more than 30years ago were studied. Three fractions of fresh CSF were examined for microparticles by flow cytometry analysis, which measure the specific binding of antibodies to CD42a (platelet-MP; 33 GPIX), CD144 (endothelial-MP; Ve-cadherin), CD45 (leukocyte-MP; pan-leukocyte antigen) and of phosphatidylserine to lactadherin. The patients with schizophrenia displayed more phosphatidylserine-positive MPs in CSF compared with healthy control subjects. The scanning electron microscopic (SEM) structures in CSF studied over a 3-year period in twins with schizophrenia were of similar appearance at both time points. The increased number of MPs in fresh CSF may be a sign of enhanced membrane shedding in the central nervous system. Such MPs can be investigated for both human and non-human DNA, RNA and microRNA that may activate different immune signaling systems in patients with schizophrenia.

Serum and cerebrospinal fluid prolactin levels in male and female patients with clinically-isolated syndrome or relapsing-remitting multiple sclerosis

There is considerable evidence that prolactin (PRL) exerts immunomodulatory actions, thus being involved in the processes of autoimmune diseases. Animal studies suggest that elevated serum PRL levels may be related to neuroprotection or participate in remyelination after brain injury. To address this question, we estimated PRL levels in both serum and cerebrospinal fluid (CSF) in drug-free male and female patients with clinically-isolated syndrome (CIS) suggestive of MS (i.e. after the first episode) as well as in patients with relapsing-remitting (RR) MS after two or more relapses, and related them to clinical, paraclinical and laboratory data. Seventy two patients with RR MS and 80 patients with CIS in the age range 17-61 years were studied. PRL levels of patients were compared with 74 control subjects, separately for males and females. Significantly higher PRL levels in serum and CSF were found in female RRMS patients but not in males. Patients with CIS had normal PRL levels. No associations were found with disease activity, duration of illness, presence of active lesions or the presence of oligoclonal bands in CSF. The elevated PRL levels observed in female but not in male RRMS patients, or in patients with CIS, could be suggestive of a sexually dimorphic response to central nervous system injury as a result of an increased proneness of females to synthesise and release PRL, which is possibly linked to the relatively more favourable prognosis of MS in women.