Background Mental disorders in comorbidity with chronic skin diseases may worsen disease outcome and patients’ quality of life. We hypothesized the comorbidity of depression, anxiety syndromes, or symptoms as attributable to biological mechanisms that the combined diseases share. Methods We conducted a systematic review based on the Preferred Reporting Items for Systematic Review and Meta-Analysis statement searching into PubMed, PsycInfo, and Scopus databases. We examined the literature regarding the comorbidity of psoriasis (Ps), atopic dermatitis (AD), or hidradenitis suppurativa with depression and/or anxiety in adults ≥18 years and the hypothetical shared underlying biological mechanisms. Results Sixteen studies were analyzed, mostly regarding Ps and AD. Brain-derived neurotrophic factor/tropomyosin receptor kinase B signaling and nuclear factor kappa-light-chain-enhancer of activated B cells/p38 mitogen-activated protein kinase pathways arose as shared mechanisms in Ps animal models with depression- and/or anxiety-like behaviors. Activated microglia and neuroinflammatory responses emerged in AD depressive models. As to genetic studies, atopic-dermatitis patients with comorbid anxiety traits carried the short variant of serotonin transporter and a polymorphism of the human translocator protein gene. A GA genotype of catechol-O-methyltransferase gene was instead associated with Ps. Reduced natural killer cell activity, IL-4, serotonin serum levels, and increased plasma cortisol and IgE levels were hypothesized in comorbid depressive AD patients. In Ps patients with comorbid depression, high serum concentrations of IL-6 and IL-18, as well as IL-17A, were presumed to act as shared inflammatory mechanisms. Conclusions Further studies should investigate mental disorders and chronic skin diseases concurrently across patients’ life course and identify their temporal relation and biological correlates. Future research should also identify biological characteristics of individuals at high risk of the comorbid disorders and associated complications.

Despite methodological limitations, real-world studies might support clinicians by broadening the knowledge of antipsychotics’ (APs) effectiveness and tolerability in different clinical scenarios and complement clinical trials. We conducted an extensive literature search in the PubMed database to evaluate the effectiveness and tolerability profiles of second-generation antipsychotics (SGAs) from real-world studies to aid clinicians and researchers in selecting the proper treatment for patients with schizophrenia and related disorders. The present review evidenced that SGAs demonstrated superior effectiveness over first-generation antipsychotics (FGAs) in relapse-free survival and psychiatric hospitalization rate and for treating negative symptoms. Persistence and adherence to therapy were higher in SGAs than FGAs. Most studies concluded that switching to long-acting injectables (LAIs) was significantly associated with a lower treatment failure rate than monotherapy with oral SGAs. Considerable improvements in general functionality, subjective well-being, and total score on global satisfaction tests, besides improved personal and social performance, were reported in some studies on patients treated with LAI SGAs. Clozapine was also associated with the lowest rates of treatment failure and greater effectiveness over the other SGAs, although with more severe side effects. Effectiveness on primary negative symptoms and cognitive deficits was rarely measured in these studies. Based on the data analyzed in the present review, new treatments are needed with better tolerability and improved effectiveness for negative, affective, and cognitive symptoms.

SARS-CoV-2 neuroinvasive and neurotropic abilities may underlie delirium onset and neuropsychiatric outcomes. Only a limited number of studies have addressed the potential effect of SARS-CoV-2 infection on mental health so far. Most studies mainly reported the acute onset of mixed neuropsychiatric conditions in patients infected with SARS-CoV-2, characterized by agitated behavior, altered level of consciousness, and disorganized thinking, regardless of psychological or socioeconomic triggering factors. The present narrative review aims to analyze and discuss the mechanisms underlying the neuroinvasive/neurotropic properties of SARS-CoV-2 and the subsequent mental complications. Delirium appeared as a clinical manifestation of SARS-CoV-2 brain infection in some patients, without systemic or multiple organ failure symptoms. A small number of studies demonstrated that neuropsychiatric symptoms associated with COVID-19, initially presenting as a confused state, may subsequently evolve in a way that is consistent with the patients’ neuropsychiatric history. A literature analysis on this topic prevalently showed case reports and case series of patients presenting delirium or delirium-like symptoms as the main outburst of COVID-19, plus a cognitive impairment, from mild to severe, which pre-existed or was demonstrated during the acute phase or after infection. Dementia appeared as one of the most frequent predisposing factors to SARS-CoV-2 infection complicated with delirium. Instead, contrasting data emerged on the potential link between COVID-19 and delirium in patients with cognitive impairment and without a neuropsychiatric history. Therefore, clinicians should contemplate the possibility that COVID-19 appears as delirium followed by a psychiatric exacerbation, even without other systemic symptoms. In addition, cognitive impairment might act as a predisposing factor for COVID-19 in patients with delirium.

Human coronaviruses have neuroinvasive and neurotropic abilities that might explain psychiatric outcomes in affected patients. We hypothesized that delirium might be the sole clinical manifestation or even the prodrome of a psychiatric episode consistent with the mental history of a few infected patients with a preexisting diagnosed cognitive impairment. We examined three patients with preexisting mild cognitive impairment and delirium at admission for suspected SARS-CoV-2 infection. We diagnosed delirium using DSM-5 and Confusion Assessment Method (CAM) and measured consciousness level by the Glasgow Coma Scale. All the patients had no history of fever, respiratory complications, anosmia or ageusia, meningitis, and negative cerebrospinal fluid analysis for SARS-CoV-2. Our first patient had no psychiatric history, the second reported only a depressive episode, and the third had a history of bipolar disorder dated back to 40 years before. In the first patient, delirium resolved 2 days following the admission. The other two patients recovered in 4 and 14 days, and delirium appeared as the prodrome of a new psychiatric episode resembling past events. Clinicians should monitor the possibility that SARS-CoV-2 presence in the brain might clinically manifest in the form of delirium and acute psychiatric sequelae, even without other systemic symptoms. Psychiatric history and preexisting mild cognitive impairment are to be considered as predisposing factors for COVID-19 sequelae in delirium patients.