Major depressive disorder (MDD) is a common and debilitating mental health disorder, characterized by persistent feelings of a low mood or inability to experience pleasure that is associated with a diminished interest in daily activities and changes in neurovegetative symptoms [1]. MDD is a heterogenous disorder, in which the remission rate is around 30–40 % following the initial medication trial and about 50–55 % after a subsequent trial, and there can be a lengthy process of trial and error to identify the optimal treatment [2,3].

Obsessive-Compulsive Disorder (OCD) is a prevalent psychiatric condition known for its resistance to conventional treatments. Despite available pharmacological and psychotherapeutic interventions, a significant number of patients do not respond adequately to these approaches. Recent genome-wide association studies (GWAS) have identified genetic links to OCD, sparking interest in exploring gene therapy as an alternative treatment method.

Despite the significant improvements in global health over the last decades, heart disease, and psychological disorders remain of the most significant global health burdens that are associated with increased mortality and morbidity [1]. Many observational studies and meta-analyses have already underlined that depression and anxiety are associated with higher risk of cardiovascular disease (CVD) [2,3,4,45]. Growing evidence indicates a complex path between symptoms of depression, anxiety and the onset and mortality of CVD [5,6,7,8,9,10,45].

Treatment-Resistant Depression (TRD) represents a significant challenge in the clinical management of depression, affecting approximately 20 % to 30 % of patients with Major Depressive Disorder (MDD) [1,2]. TRD is generally defined as the failure to achieve remission after two or more adequate trials of antidepressants from different classes, at appropriate doses and durations, often also including non-response to evidence-based psychotherapies such as Cognitive Behavioral Therapy (CBT) [3,4]. This condition leads to substantial negative impacts on patients’ quality of life, daily functioning, and increases the risk of relapse and suicide [5].

Psychological distress is mainly characterized as a state of emotional suffering that is accompanied by symptoms of depression, anxiety, anger, insomnia, cognitive problems, and somatization [1,2]. In other words, psychological distress is an undifferentiated group of symptoms that range from symptoms of depression and anxiety to behavioral problems, functional impairment, and personality traits [1]. Although psychological distress is defined as a non-specific mental health problem, it is characterized by symptoms of depression and anxiety and they are not entirely independent [3,4].