clozapine and Neurodegenerative-Diseases

It is widely accepted that schizophrenia originates from abnormalities occurring during the early stages of neural development. Although large studies have revealed behavioral precursors of schizophrenia in childhood, the disorder is usually not evident until patients are in their 20s or 30s. Some patients will be resistant to typical antipsychotic treatment at this first-onset of schizophrenia; however, treatment resistance develops in the majority of patients during the course of successive episodes. This ongoing deterioration suggests that a degenerative process operates during the active psychotic phase of the illness. This review presents evidence of neurodevelopmental and neurodegenerative mechanisms for the development of schizophrenia. These data indicate the importance of effective treatment at the first onset of schizophrenia to improve patient outcome. In addition, animal studies suggest that treatment with clozapine may prevent the neurodegenerative component responsible for the development of treatment resistance.

Topics: Animals; Antipsychotic Agents; Brain; Clozapine; Disease Models, Animal; Drug Resistance; Female; Humans; Magnetic Resonance Imaging; Male; Mice; Neurodegenerative Diseases; Pregnancy; Rats; Schizophrenia; Schizophrenic Psychology; Treatment Outcome

Schizophrenia, a complex psychiatric disorder, is often associated with cognitive, neurological and neuroimaging abnormalities. The processes underlying these abnormalities, and whether a subset of people with schizophrenia have a neuroprogressive or neurodegenerative component to schizophrenia, remain largely unknown. Examining fluid biomarkers of diverse types of neuronal damage could increase our understanding of these processes, as well as potentially provide clinically useful biomarkers, for example with assisting with differentiation from progressive neurodegenerative disorders such as Alzheimer and frontotemporal dementias.. We found no differences in NfL levels between treatment-resistant schizophrenia (mean NfL, M = 6.3 pg/mL, 95% confidence interval: [5.5, 7.2]), first-degree relatives (siblings, M = 6.7 pg/mL, 95% confidence interval: [5.2, 8.2]; parents, M after adjusting for age = 6.7 pg/mL, 95% confidence interval: [4.7, 8.8]), controls (M = 5.8 pg/mL, 95% confidence interval: [5.3, 6.3]) and not treated with clozapine (M = 4.9 pg/mL, 95% confidence interval: [4.0, 5.8]). Exploratory, hypothesis-generating analyses found weak correlations in treatment-resistant schizophrenia, between NfL and clozapine levels (Spearman's. Treatment-resistant schizophrenia does not appear to be associated with neuronal, particularly axonal degeneration. Further studies are warranted to investigate the utility of NfL to differentiate treatment-resistant schizophrenia from neurodegenerative disorders such as behavioural variant frontotemporal dementia, and to explore NfL in other stages of schizophrenia such as the prodome and first episode.

Topics: Alzheimer Disease; Biomarkers; Child; Clozapine; Frontotemporal Dementia; Humans; Intermediate Filaments; Neurodegenerative Diseases; Neurofilament Proteins; Schizophrenia; Schizophrenia, Treatment-Resistant

Topics: Clozapine; Humans; Neurodegenerative Diseases; Parkinson Disease; Psychotic Disorders; Quetiapine Fumarate; United States

Designer receptors exclusively activated by designer drugs (DREADDs) are novel and powerful tools to investigate discrete neuronal populations in the brain. We have used DREADDs to stimulate degenerating neurons in a Down syndrome (DS) model, Ts65Dn mice. Individuals with DS develop Alzheimer's disease (AD) neuropathology and have elevated risk for dementia starting in their 30s and 40s. Individuals with DS often exhibit working memory deficits coupled with degeneration of the locus coeruleus (LC) norepinephrine (NE) neurons. It is thought that LC degeneration precedes other AD-related neuronal loss, and LC noradrenergic integrity is important for executive function, working memory, and attention. Previous studies have shown that LC-enhancing drugs can slow the progression of AD pathology, including amyloid aggregation, oxidative stress, and inflammation. We have shown that LC degeneration in Ts65Dn mice leads to exaggerated memory loss and neuronal degeneration. We used a DREADD, hM3Dq, administered via adeno-associated virus into the LC under a synthetic promoter, PRSx8, to selectively stimulate LC neurons by exogenous administration of the inert DREADD ligand clozapine-N-oxide. DREADD stimulation of LC-NE enhanced performance in a novel object recognition task and reduced hyperactivity in Ts65Dn mice, without significant behavioral effects in controls. To confirm that the noradrenergic transmitter system was responsible for the enhanced memory function, the NE prodrug l-threo-dihydroxyphenylserine was administered in Ts65Dn and normosomic littermate control mice, and produced similar behavioral results. Thus, NE stimulation may prevent memory loss in Ts65Dn mice, and may hold promise for treatment in individuals with DS and dementia.

Topics: Animals; Antipsychotic Agents; Cell Count; Clozapine; Cross-Over Studies; Designer Drugs; Disease Models, Animal; Down Syndrome; Exploratory Behavior; Gene Expression Regulation; Humans; Locus Coeruleus; Male; Maze Learning; Memory Disorders; Mice; Mice, Neurologic Mutants; Motor Activity; Neurodegenerative Diseases; Receptor, Muscarinic M3; Serine

Fahr's syndrome is a rare disorder characterized by abnormal deposits of calcium in areas of the brain that control movement, including the basal ganglia and the cerebral cortex associated with many neurological and psychiatric abnormalities such as a rigid hypokinetic syndrome, mood disorders and cognitive impairment. Fahr's syndrome is secondary to some disorders, such as hypoparathyroidism.. We report the case of a 56 year-old man, with a history of cataract, who was admitted to our psychiatric hospital for the first time in his life because of psychotic symptoms associated with irritability and aggressiveness. Since the age of 38 the patient had become nervous, 10 years later he developed tonic-clonic seizures. Two months ago, he began expressing delusions of persecution against his wife and sons and making fugues. According to his family during this period, he was agitated, aggressive, and suffered from insomnia and anorexia. The general and psychiatric examination showed an upright and bronzed patient with neglected hygiene. He was indifferent to his environment and expressed poor mimics and gestures. He was anxious, suspicious and not very talkative. He was conscious but his attention was slightly decreased. Moreover, he was not aware of his problems. The neurological examination showed extrapyramidal syndrome with postural tremor and cerebellar ataxia. A cranial computed tomography brain scan found bilateral, symmetric basal ganglia calcifications, in favour of Fahr's syndrome. Phosphocalcic investigations revealed low concentration of serum calcium at 1.01mmol/L (normal 2.15 to 2.57mmol/L) and hyperphosphoremia at 2.69mmol/L (normal 0.81 to 1.55mmol/L). He also had low concentrations of 25-OH vitamin as well as decreased urinary levels of phosphate and calcium. The blood level of parathyroid hormone was 0ng/L. The diagnosis of Fahr's syndrome, revealing a hypoparathyroidism was posed. He was supplemented with calcium and alpha cholecalciferol and treated with clozapine (100mg per day). After four weeks, psychotic symptoms responded well to this treatment without expressing any side effects, notably seizures.. Psychotic symptoms seen in Fahr's disease include auditory and visual hallucinations, complex perceptual distortions, delusions, and fugue state. Some of them were manifest in this patient. It is likely that the psychosis in both Fahr's disease and schizophrenia share a similar pathology. Positive psychotic symptoms, hallucinations, and paranoia are not necessarily generated by the classical hypothesis of dopamine-mediated attachment of salience to internally generated stimuli. Still, there is some evidence that disruption of the cortex involved in the pathophysiology of schizophrenia is also seen in Fahr's disease, particularly in areas of the limbic system.. Psychiatrists should consider Fahr's syndrome as a differential diagnosis in the evaluation of psychosis associated with seizures. This case, along with others in the literature, further emphasizes the importance of the role of neuro-imaging and the search for disrupted phosphocalcic metabolism in patients with atypical psychotic symptoms. Moreover, further research should focus on pharmacologic interventions. The efficacy and risks of neuropharmacologic and psychopharmacologic interventions in Fahr's syndrome, and correlates of good and poor outcome with these interventions remain to be defined.

Topics: Basal Ganglia; Basal Ganglia Diseases; Brain Diseases; Calcinosis; Calcium; Cholecalciferol; Clozapine; Humans; Hypoparathyroidism; Male; Middle Aged; Neurocognitive Disorders; Neurodegenerative Diseases; Tomography, X-Ray Computed

Phencyclidine (PCP) administration in rats acutely in high doses or chronically in lower doses causes neurotoxicity characterized by neuronal vacuolization and apoptotic neuronal death, respectively. The purpose of this study was to determine whether drugs that previously had been reported to prevent either type of neurotoxicity were also able to prevent locomotor sensitization following chronic PCP administration. PCP (5 or 20 mg/kg) was administered once a day for 5 days following drug pretreatment. After withdrawal, rats were challenged with 3.2 mg/kg PCP and locomotor activity was assessed. Haloperidol and clozapine significantly attenuated sensitization elicited by PCP (20 mg/kg). The D(1)-like antagonist SCH23390 was much less effective than clozapine, showing a marginal inhibition. Risperidone, a D(2)/serotonin (5-HT(2)) antagonist, also resulted in a marginal attenuation of 15%. Ketanserin, a 5-HT(2) antagonist, had no effect. Atropine retarded sensitization by 35% and (+)-sulpiride caused a 50% reduction. The AMPA/kainate antagonist, 6,7-dinitroquinoxaline-2,3-dione, had no effect, but barbital sodium reduced sensitization by 54%. These data suggest that gamma-aminobutyric acid A, D(2), and muscarinic receptors play a major role in the complex pathway underlying sensitization to PCP, whereas D(1), 5-HT(2) and AMPA receptors have little or no relevance in the behavioral sensitization produced by 20 mg/kg PCP. In a model using 5 mg/kg PCP, the effects of sulpiride and SCH23390 replicated those observed with 20 mg/kg PCP and further showed that acute locomotor activation is not a strict requirement for the development of sensitization. These data argue that there is overlap, but nonidentity, between the mechanisms underlying PCP-induced sensitization and neurotoxicity.

Topics: Animals; Clozapine; Excitatory Amino Acid Antagonists; Female; GABA Antagonists; Motor Activity; Neurodegenerative Diseases; Phencyclidine; Rats; Rats, Sprague-Dawley