The goal of medicine is to alleviate pain and suffering, and to that end, neuropsychiatry has focused on identifying pathology, establishing diagnostic criteria, and developing treatments. Yet many patients who are in distress have symptom constellations that do not meet the criteria for a defined neurological condition or DSM diagnosis. This chapter discusses presentations that fall outside the realm of current diagnostic categories, including dimensional symptoms, variations in neuropsychological functioning that may lead to difficulties even when within the range of normal, and problems that are traditionally considered to reside in the domain of psychology, although they emerge from the materiality of brain—internal mental conflicts, relationship difficulties, and maladaptive patterns of behavior.
While the care of all patients rests on a clinician’s understanding of the patient as an individual, this is especially true when treating patients who do not meet criteria for diagnostic categories and, therefore, whose treatment is less prescribed. Designing and delivering treatments for an individual patient’s specific health situation requires complex problem solving. The foundation for this personalized treatment within a clinician-patient relationship is an understanding of each patient as a whole person, including an appreciation for the patient’s neuropsychological difficulties, personality and temperament, personal history, cultural background, family, and social situation. In addition, each person is more than the sum of parameters that are shared by all human beings; each person is unique in ways that are challenging to define scientifically. An awareness of the biological basis of individuality at every scale (from molecule and cell to personality and behavior) may help clinicians to conceptualize how individuals can be both similar and unique.
Even identical twins who begin with identical genomes have become different individuals by the time they are born.1,2 While clinicians recognize that all patients begin life with certain inherent characteristics, the tendency of clinicians is to focus on postnatal forces that shape individuals from childhood through adulthood such as birth trauma, parental influence, nutrition, toxic exposure, education, religious and cultural forces, socioeconomic factors, and other life experiences including environmental enrichment, illness, loss, abuse, emotional and/or physical trauma, and therapy. Patients and their families are able to report about these factors and describe their experiences. From a practitioner’s frame of reference, it is possible to assemble a large-scale narrative of how a person’s life has unfolded, including how this particular individual has emerged from a unique life history. However, many aspects of individuality are largely established by the time of birth, as a result of genetic, epigenetic, developmental processes and also random (stochastic) molecular events.2
Because understanding the individual patient is fundamental to the psychotherapies and also to personalized medicine, the first portion of this chapter outlines some of the complex biological mechanisms that contribute to shaping individuality at the level of the brain; while the scientific study of brain-behavior differences between normal individuals is in its infancy, this discussion may serve as an ...