Major depressive disorder (MDD) is one of the most common unipolar affective disorders for individuals of all ages and is associated with hypofunction of the serotonergic system. Although there is no consensus regarding the cause of depression, theories such as the monoamine theory or the neurotransmitter hypothesis contribute to scientists’ understanding of depression. These theories discuss imbalances of serotonin, dopamine, and norepinephrine and other modulating neurohormones. More contemporary theories consider depression to be a clinically heterogeneous disorder because depression originates from genetic, biochemical, and environmental factors. Depression rates increase from childhood through adolescence and into adulthood. Early recognition and intervention are the key to treatment. Treatment for depression includes psychotherapy and antidepressant medications to minimize clinical morbidity and improve clinical outcomes. Although the risk of suicidality may increase upon initiation of antidepressants, suicide risk also increases with untreated depression; therefore, careful consideration is required when managing depressed individuals (Gautam et al., 2017). This chapter details medications for the treatment of MDD.

Psychiatric mental health nurse practitioners (PMHNPs) apply a holistic and patient-centered approach to diminish mental distress and help mental health sufferers set attainable goals and have hope for the future. Using theoretically grounded methods, PMHNPs are trained experts in the evaluation and treatment of patients with disordered feelings, thoughts, and behaviors. Structured interviews, semistructured interviews, and questionnaires have become the gold standard for diagnostic interviewing for psychiatric mental health assessments. The goal of this chapter is to offer the knowledge and skills required to conduct a mental health evaluation across populations.

Psychologic interventions include a broad range of treatment possibilities that aim to modify behaviors, emotions, or feelings to maximize an individual’s overall functioning and well-being. Psychologic interventions can be delivered to an individual, a group, or a combination of both. The National Institute of Health and Care Excellence guidelines discuss the evidence and the role of psychologic interventions for improving clinical outcomes in individuals with mental health conditions and consider the distinct needs of individuals and their families. Encouraging strong family, caregiver, and school partnerships that include coordinating efforts and help with management may enhance the effects of psychosocial treatments.

Neurodevelopmental disorders (NDs) are a group of acquired developmental conditions that impact both cognitive and social communicative development, including an individual’s cognition, language, behavior, gross motor skills, interpersonal relationships, and organization skills. In turn, the impairment of these skills impacts personal, social, academic, and/or occupational functioning (Rosenblum et al., 2019). NDs are considered the most prevalent chronic medical condition encountered in pediatric primary care, and are typically diagnosed during infancy, childhood, or adolescence, with a chronic course of impairment generally lasting into adulthood.

Neurocognitive disorders (NCDs), previously referred to as “dementia,”, are syndromes that affect the brain. NCDs are characterized by a progressive decline in cognitive functioning that involves loss of memory, difficulty thinking, and changes in mood and behavior. The term “dementia” is still used to describe degenerative dementia that affects older adults. The term “cognition” refers to the process of receiving knowledge and understanding in areas such as psychomotor speed, attention, working memory, declarative memory (verbal and visual), and executive functioning, including planning, decision-making, response inhibition, and cognitive flexibility (Chakrabarty et al., 2016).

Neurotransmitters are endogenous chemicals that enable communication between neurons. Specifically, neurotransmitters are the brain chemicals that help relay messages from one part of the brain to another and between the brain and the rest of the body, primarily through synaptic transmission, also referred to as neurotransmission. The signals sent by neurotransmitters are responsible for the vast majority of brain and motor functions, including memory, planning, heart rate, respirations, digestion, hormonal responses, movement, and others. Many different diseases involve increased or decreased levels of neurotransmitters in the brain, which lead to different clinical features. Understanding the role of neurotransmitters and receptors in the brain is essential to gain insights into the neural bases of critical brain functions and pathological conditions, such as anxiety, depression, schizophrenia, Parkinson’s disease, drug addiction, learning problems, and many more. This chapter will provide an overview of (a) the different types of neurotransmitters and their functions, (b) the fundamental mechanisms of neuronal excitability, (c) signal generation and transmission, (d) synaptic transmission, (e) neural plasticity, (f) different types of receptors, and (g) the different illnesses and medications that target these receptors.

Anxiety disorders, which can range from mild to severe, impact both children and adults and are among the most prevalent mental health disorders worldwide. Anxiety disorders that manifest in childhood are linked with educational underachievement, co-occurring psychiatric conditions, significant functional impairment, increased risk for substance misuse, and negative outcomes later in life (Katzman et al., 2014; Reardon et al., 2019). Anxiety encompasses a heterogeneous group of conditions that can be characterized by a state of pervasive, unwarranted worry, nervousness, apprehension, and uneasiness that is difficult to control, causes significant distress and impairment, and occurs on more days than not over a period of 6 months. Acute attacks of anxiety include periods of intense motor and visceral activation, distortions of perception, loss of concentration, and impaired cognition, and may result in temporary debilitation (Kuang et al., 2017). Risk factors that place younger individuals at risk for anxiety include biologic influences, temperament, and environmental factors, such as stressful life experiences, parenting behaviors, and modeling.

Sleep is an innate biologic requirement for human life that plays a key role in mental and physical health. Restful sleep reverses oxidative stress, repletes energy stores, is vital to learning and memory, and impacts overall functioning. In the United States, approximately 30% of adults report that they sleep less than 7 hours per 24 hours and are chronically sleep deprived. Additionally, approximately 50% to 80% of adults with mental illnesses report difficulties with falling or staying asleep (Seow et al., 2018; Slavish et al., 2019). Sleep disturbance and mental health conditions are closely intertwined; disrupted sleep is either a symptom or a consequence of a mental health condition (Freeman et al., 2017), and disturbed sleep is a contributory factor in the occurrence of mental health disorders (Mead & Irish, 2020). This chapter provides a brief overview of insomnia along with the causes of, evidence in assessing, and how to diagnose, treat, and manage insomnia.

The brain is a massive network that contains billions of cells and nerve fibers. Due to the brain’s interconnectedness to vital organ systems and its complicated neuroanatomy, it is considered to be the most complex organ within the body. For decades, scientists have tried to comprehend how the brain and nervous system function. In fact, neurochemical transmission was recognized prior to the 1950s, and scientists believed that central nervous system neurons communicated through electrical impulses (Braslow & Marder, 2019). This chapter highlights the brain’s major structures and provides an overview of the central and peripheral nervous systems, basic concepts of neurotransmission, and general principles of pharmacology.

Communication impacts all levels of care, including diagnostic accuracy, treatment, monitoring, and clinical outcomes. Clinicians use bidirectional communication and interpersonal skills to obtain information, facilitate care, provide counsel, and establish therapeutic relationships. Patient–provider communication and interactions contribute to increased patient adherence and positive health outcomes. The clinician’s verbal and nonverbal communication is important during the psychiatric interview and can impact pertinent information sharing, delivery of diagnosis, and other therapeutic processes (McCabe & Healey, 2018).