[The endocannabinoid system and its possible role in neurobiology of psychiatric disorders]. / Il sistema endocannabinoide e il suo possibile ruolo nella neurobiologia dei disturbi psichiatrici.

In the last years, numerous researches led to identify endocannabinoid system, a sophisticated short-range signaling system which is located both in Central Nervous System (CNS) and in whole organism. Because of its flexibility of expression, it plays a modulatory role in controlling the answers to stimuli which disturb homeostasis. On one hand it lets them occur whilst on the other it limits them in order to protect organism from consequences due to excessive reaction. In the CNS, endocannabinoid system is able to control the release of several neurotransmitters thanks to its retrograde signaling, modulating synaptic activity. Analysing this property during preclinical studies, it came out that the endocannabinoid system is involved in numerous physiologic processes, such as neuroendocrine axes, food consumption, brain reward and satisfaction mechanisms, memories storing and extinction, emotions and neurodevelopment regulation. Such discoveries have led researchers to suppose and investigate an alteration of this system in the physiopathology of some psychiatric disorders such as anxiety disorder, depression, eating disorders, addiction and schizophrenia. Results of such studies on animal models show a possible involvement of this system and were quickly followed by clinical studies which seem to confirm it. These findings might open new scenarios for understanding the pathogenesis of several psychiatric disorders and, at same time, they show new prospects for their treatment.

Olfactory identification deficits and associated response inhibition in obsessive-compulsive disorder: on the scent of the orbitofronto-striatal model.

Olfactory identification ability implicates the integrity of the orbitofrontal cortex (OFC). The fronto-striatal circuits including the OFC have been involved in the neuropathology of Obsessive Compulsive Disorder (OCD). However, only a few studies have examined olfactory function in patients with OCD. The Brief Smell Identification Test (B-SIT) and tests from the Cambridge Neuropsychological Automated Battery (CANTAB) were administered to 25 patients with OCD and to 21 healthy matched controls. OCD patients showed a significant impairment in olfactory identification ability as well as widely distributed cognitive deficits in visual memory, executive functions, attention, and response inhibition. The degree of behavioural impairment on motor impulsivity (prolonged response inhibition Stop-Signal Reaction Time) strongly correlated with the B-SIT score. Our study is the first to indicate a shared OFC pathological neural substrate underlying olfactory identification impairment, impulsivity, and OCD. Deficits in visual memory, executive functions and attention further indicate that regions outside of the orbitofronto-striatal loop may be involved in this disorder. Such results may help delineate the clinical complexity of OCD and support more targeted investigations and interventions. In this regard, research on the potential diagnostic utility of olfactory identification deficits in the assessment of OCD would certainly be useful.

[Dissociative symptoms in patients with mood and anxiety disorders]. / Presenza di elementi dissociativi in pazienti con disturbi dell'umore e disturbi d'ansia.

AIM: The objective of this study was to evaluate the occurrence of dissociative symptoms in outpatients affected by mood or anxiety disorder and their potential implication in general psychopathology and treatment response. METHODS: The sample was recruited at Italian and Spanish psychiatric outpatient services. The sample consisted in 40 (13 Male, 27 Female) outpatients, 22 Italians (55%) and 18 Spanish (45%). Inclusion criteria were the Axis I diagnosis of any DSM-IV-TR mood or anxiety disorder and Clinical Global Impression/Global Severity Index (CGI) baseline scores > or = 3 and Hamilton Depression Rating Scale (HAM-D) and Hamilton Anxiety Scale (HAM-A) baseline scores > or = 18. General psychopathology, dissociative symptoms and personality traits were respectively assessed by the self-report symptom inventory Symptom Check-List 90 (SCL-90), the Dissociative Experience Scale (DES) and the Cloninger's Temperament and Character Inventory (TCI). RESULTS: Dissociative symptoms emerged as relatively frequent in mood and anxiety disorders. Globally, depression symptoms seem to correlate positively with the dissociative experiences and the severity of global psychopathology. Dissociative symptoms seem to correlate positively with some personality traits and the severity of global psychopathology and should receive further investigation in clinical practice, as might be a predictor of poor response to conventional drug treatment.

Corpus callosum abnormalities and potential age effect in men with schizophrenia: an MRI comparative study.

The goal of this investigation was to evaluate corpus callosum (CC) morphometry in schizophrenia. In consideration of possible confounders such as age, gender and handedness, our study sample was restricted to right-handed male subjects, aged 18-55 years. In addition, we controlled for age at onset, illness duration and exposure to antipsychotic medication. Midsagittal CC linear and area Magnetic Resonance Imaging (MRI) measurements were performed on 50 subjects with schizophrenia and 50 healthy controls. After controlling for midsagittal cortical brain area and age, Analysis of Covariance (ANCOVA) revealed an overall effect of diagnosis on CC splenium width and CC anterior midbody area and a diagnosis by age interaction. Independent Student t tests revealed a smaller CC splenium width in the 36- to 45-year-old age group among the patients with schizophrenia and a smaller CC anterior midbody area in the 18- to 25-year-old age group among the patients with schizophrenia compared with controls. Age, age at onset, illness duration and psychopathology ratings did not show any significant correlations with the whole CC MRI measurements. A negative correlation was found between CC rostrum area and the estimated lifetime neuroleptic consumption. The results are discussed in terms of the possibility that CC structural changes may underlie the functional impairments, frequently reported in schizophrenia, of the associated cortical regions.