Is it more effective for anhedonia and avolition? A systematic review and meta-analysis of non-invasive brain stimulation interventions for negative symptoms in schizophrenia.

BACKGROUND: Noninvasive brain stimulation (NIBS) techniques are a promising tool for treating the negative symptoms of schizophrenia. Growing evidence suggests that different dimensions of negative symptoms have partly distinct underlying pathophysiological mechanisms. Previous randomized controlled trials (RCTs) have shown inconsistent impacts of NIBS across dimensions. OBJECTIVE: This systematic review and meta-analysis evaluated the effects of NIBS on general negative symptoms, and on specific domains, including blunted affect, alogia, asociality, anhedonia, and avolition. DATA SOURCES: PubMed, Web of Science, Embase, Cochrane CENTRAL, PsycINFO, OpenGrey, and Clinicaltrials.gov from the first date available to October, 2023. RESULTS: Among 1049 studies, we identified eight high-quality RCTs. NIBS significantly affects general negative symptoms (SMD = -0.54, 95% CI [-0.88, -0.21]) and all five domains (SMD = -0.32 to -0.63). Among dimensions, better effects have been shown for improvement of avolition (SMD = -0.47, 95% CI [-0.81, -0.13]) and anhedonia (SMD = -0.63, 95% CI [-0.98, -0.28]). Subgroup analyses of studies that applied once daily stimulation or >10 sessions showed significantly reduced negative symptom severity. CONCLUSION: NIBS exerts distinct effects across multiple dimensions of negative symptom, with treatment effects related to stimulation frequency and total sessions. These results need to be confirmed in dedicated studies.

Do you remember if you have olfactory dreams? A content analysis of LOFTER and a questionnaire survey conducted in China.

OBJECTIVES: Dreams often involve visual and auditory sensations, but olfactory experiences have not received the same amount of attention. This study explores the prevalence and content of olfactory dreams in China and investigates the relationship between olfactory imagery, olfactory significance, and olfactory dreamers. METHODS: In the first part of the study, 4302 dream records from LOFTER were screened and classified to preliminarily identify the prevalence and content of olfactory dreams. In the second part, 718 participants completed an online questionnaire about olfactory dreams, imagery, and significance. RESULTS: The prevalence of olfactory dreams in the diary dream entries and questionnaire survey participants were 3.95% and 18.70%, respectively. Instances in which odors appeared in dreams were more positive than negative and were mainly related to food, burning and smoke, body odor, nature, and certain environments and objects. Moreover, individuals with olfactory dreams showed better olfactory imagery, and stronger olfactory significance. CONCLUSIONS: Olfactory sensations occurred in the dreams of Chinese individuals, but their prevalence was very low. Most of the odors that emerged in these dreams were ones that the dreamers were familiar with in their daily lives.

Altered grey matter volume and cortical thickness in patients with schizo-obsessive comorbidity.

Recent findings suggest that schizo-obsessive comorbidity (SOC) may be a unique diagnostic entity. We examined grey matter (GM) volume and cortical thickness in 22 patients with SOC, and compared them with 21 schizophrenia (SCZ) patients, 22 obsessive-compulsive disorder (OCD) patients and 22 healthy controls (HCs). We found that patients with SOC exhibited reduced GM volume in the left thalamus, the left inferior semi-lunar lobule of the cerebellum, the bilateral medial orbitofrontal cortex (medial oFC), the medial superior frontal gyrus (medial sFG), the rectus gyrus and the anterior cingulate cortex (aCC) compared with HCs. Patients with SOC also exhibited reduced cortical thickness in the right superior temporal gyrus (sTG), the right angular gyrus, the right supplementary motor area (SMA), the right middle cingulate cortex (mCC) and the right middle occipital gyrus (mOG) compared with HCs. Together with the differences in GM volume and cortical thickness between patients with SOC and patients with only SCZ or only OCD, these findings highlight the GM changes specific to patients with SOC.