Presynaptic dopaminergic function: implications for understanding treatment response in psychosis

Worsening psychosis associated with administrations of buspirone and concerns for intranasal administration: A case report

Buspirone is commonly used to treat generalized anxiety disorder and demonstrates a limited side-effect profile compared to other anxiolytics. Buspirone is considered generally safe, and neuropsychiatric adverse reactions are uncommon. There are rare clinical case reports that suggest buspirone-induced psychosis. We present a case of buspirone worsening psychosis for a patient psychiatrically hospitalized for an episode of decompensated schizoaffective disorder. The patient had a primary diagnosis of schizoaffective disorder and was treated with antipsychotics during this hospitalization, but his symptoms worsened when buspirone was administered on two separate occasions. During the first trial of buspirone, the patient exhibited traits of increased aggression, odd behaviors, and paranoia. The buspirone was discontinued after the patient admitted to hiding his pills to later consume through nasal ingestion. The second trial resulted in repeated exacerbated symptoms of paranoia related to food and substantially decreased oral intake. Considering its complex mechanism of action, buspirone is suggested to derive its neuropharmacological effects through 5-HT1A receptors. However, the drug also has been found to mediate dopamine neurotransmission. Buspirone acts as an antagonist at presynaptic dopamine D2, D3, and D4 receptors. Yet, contrary to expected outcomes, it was unable to produce antipsychotic effects and instead resulted in a substantial increase in dopaminergic metabolites. The route of administration may also play a role in the enhancement of the buspirone's effects, particularly considering that after first-pass metabolism, buspirone has approximately 4% oral bioavailability. Intranasal administration of buspirone leads to faster drug absorption by direct transport from the nasal mucosa to the brain and increased bioavailability.

Neuropathology of the Brainstem to Mechanistically Understand and to Treat Alzheimer's Disease

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder as yet without effective therapy. Symptoms of this disorder typically reflect cortical malfunction with local neurohistopathology, which biased investigators to search for focal triggers and molecular mechanisms. Cortex, however, receives massive afferents from caudal brain structures, which do not only convey specific information but powerfully tune ensemble activity. Moreover, there is evidence that the start of AD is subcortical. The brainstem harbors monoamine systems, which establish a dense innervation in both allo- and neocortex. Monoaminergic synapses can co-release neuropeptides either by precisely terminating on cortical neurons or, when being “en passant”, can instigate local volume transmission. Especially due to its early damage, malfunction of the ascending monoaminergic system emerges as an early sign and possible trigger of AD. This review summarizes the involvement and cascaded impairment of brainstem monoaminergic neurons in AD and discusses cellular mechanisms that lead to their dysfunction. We highlight the significance and therapeutic challenges of transmitter co-release in ascending activating system, describe the role and changes of local connections and distant afferents of brainstem nuclei in AD, and summon the rapidly increasing diagnostic window during the last few years.

The Prevalence of Negative Symptoms Across the Stages of the Psychosis Continuum

BACKGROUND

Patients in every stage of the psychosis continuum can present with negative symptoms. While no treatment is currently available to address these symptoms, a more refined characterization of their course over the lifetime could help in elaborating interventions. Previous reports have separately investigated the prevalence of negative symptoms within each stage of the psychosis continuum. Our aim in this review is to compare those prevalences across stages, thereby disclosing the course of negative symptoms.

METHODS

We searched several databases for studies reporting prevalences of negative symptoms in each one of our predetermined stages of the psychosis continuum: clinical or ultra-high risk (UHR), first-episode of psychosis (FEP), and younger and older patients who have experienced multiple episodes of psychosis (MEP). We combined results using the definitions of negative symptoms detailed in the Brief Negative Symptom Scale, a recently developed tool. For each negative symptom, we averaged and weighted by the combined sample size the prevalences of each negative symptom at each stage.

RESULTS

We selected 47 studies totaling 1872 UHR, 2947 FEP, 5039 younger MEP, and 669 older MEP patients. For each negative symptom, the prevalences showed a comparable course. Each negative symptom decreased from the UHR to FEP stages and then increased from the FEP to MEP stages.

CONCLUSIONS

Certain psychological, environmental, and treatment-related factors may influence the cumulative impact of negative symptoms, presenting the possibility for early intervention to improve the long-term course.

Auditory verbal hallucinations: neuroimaging and treatment

Auditory verbal hallucinations (AVH) are a frequently occurring phenomenon in the general population and are considered a psychotic symptom when presented in the context of a psychiatric disorder. Neuroimaging literature has shown that AVH are subserved by a variety of alterations in brain structure and function, which primarily concentrate around brain regions associated with the processing of auditory verbal stimuli and with executive control functions. However, the direction of association between AVH and brain function remains equivocal in certain research areas and needs to be carefully reviewed and interpreted. When AVH have significant impact on daily functioning, several efficacious treatments can be attempted such as antipsychotic medication, brain stimulation and cognitive-behavioural therapy. Interestingly, the neural correlates of these treatments largely overlap with brain regions involved in AVH. This suggests that the efficacy of treatment corresponds to a normalization of AVH-related brain activity. In this selected review, we give a compact yet comprehensive overview of the structural and functional neuroimaging literature on AVH, with a special focus on the neural correlates of efficacious treatment.