such as brain imaging procedures or patterns of performance on neuropsychological tests. For example, individuals with a given disorder may show certain types of electroencephalogram (EEG) responses to particular stimuli or a certain pattern of brain activity that is different from that seen in healthy individuals. Those with autism have been shown to have fewer connections between brain areas than siblings or controls, and this is seen as an endophenotype (Moseley et al., 2015).
endophenotypes: patterns of processes that lie between the gene (the genotype) and the manifestations of the gene in the external environment (the phenotype)
Like genes, the presence of the endophenotype does not necessarily mean that the disorder itself will be present. For example, a specific endophenotype may be seen in both a person with schizophrenia and his or her first-degree relatives, although the relatives themselves do not have schizophrenia. As such, an endophenotype can help to identify the systems involved in a particular disorder as well as note which genes are influenced by environmental and other internal factors related to a disorder. The potential of endophenotypes is their ability to better articulate the relationship between genetic and environmental factors in the development of psychopathology and to clarify which processes are influenced. In Chapter 4, you will learn about a National Institute of Mental Health (NIMH)–supported diagnostic approach based on endophenotypes, the Research Domain Criteria (RDoC).
Concept Check
What are the two important principles of Mendelian genetics? What evidence led Mendel to their discovery?
What do genes do, and how and where do they do it? What are the roles of DNA and RNA in that process?
How do we know that genes change behavior? What kinds of research have been done with animals to identify the specific genes involved?
What is epigenetic inheritance? How does it work?
What is an endophenotype, and how does it relate to psychopathology?
Evolution and Psychopathology
Thus far, we have considered brain changes and genes turning off and on. These events are typically short term and can change quickly. Moving to the evolutionary perspective, we will look at a longer time frame in which environmental factors influence the genes that are passed on to the next generation. Let’s begin with the major themes of evolution and then consider psychopathology from an evolutionary perspective.
The Themes of Evolution
One of the main themes of evolution is the manner in which organisms are in close connection with their environment. It is this close connection that allows for change to take place, including the turning on and off of genetic processes. In humans, there is another layer of complexity involved in the process. Part of this complexity comes from the fact that humans are born less fully developed at birth than many other species and thus are sensitive to changes in their environment as they continue to develop. This includes our relationships with our family and others with whom we initially come in contact. As humans, we also develop societal and cultural perspectives. These perspectives become the backdrop of our environment. Unlike animals that live within nature, we as humans largely live within the backdrop of our culture. Thus, we are influenced by our culture and pay close attention to it.
Human infants are helpless at birth.
ERproductions Ltd/Blend Images/Getty Images
Many species are able to function on their own shortly after birth.
Doug Cheeseman/Photolibrary/Getty Images
Another part of our complexity as humans is our ability to reflect on ourselves and our world. In this way, a layer of thought can be injected between the person and the environment. This allows for expectation and imagination to play a role in human behavior and experience. Some have even suggested that humans may be the only species to imagine the world and themselves differently from how they appear. In this sense, our inner world of thoughts and feelings becomes another environment in which we live. For example, you can tell yourself you are wonderful or you are stupid, and there is no one inside you to dispute this. One positive aspect of this is that your inner world allows you to plan future actions and reflect on past ones, but it can also be experienced as distress when your internal thoughts reflect such states as anxiety or hopelessness. Our internal thoughts at times may lead to interpretations of the environment or ourselves that may not be productive. This adaptive human ability to reflect, which should lead to successful survival, sexuality, and social relations, sometimes leads instead to interactions that reduce the close connection between the individual and his or her internal and external environment. As we will see, this lack of connectedness lies at the heart of psychopathology.
As noted in Chapter 1, humans not only consider themselves but also consider others. A positive side of this is the ability to understand the internal experiences of another. This allows us to experience empathy. We can also consider how we appear to others and other questions of self-image. One aspect of this is related to sexual processes. That is, we can say or do things that make us more attractive to a potential mate. In terms of self-preservation, humans also have a personal history that allows each individual to learn from the past and develop strategies for living. These strategies tend to protect us and may even have saved our lives in exceptional cases. However, it is also possible for the strategies that work in one environmental situation not to work in another. When a person loses contact with the current environment and applies strategies that worked perhaps in an earlier time, then unsuccessful adaptation is the result.
This lack of connectedness to our environment may take place on both an external and an internal level. On an external level, the person finds herself different from the group or even seeks to be separate from others. This is not our historical experience, since individual humans have never lived in isolation. As a species, we have always lived in close contact with other humans, which has led to the development of societies and cultures. In fact, many of the specific abilities of humans are geared to social interactions on a variety of levels. When they no longer have the connection with the group, many individuals experience a sense of loss. This loss typically carries with it the experience of negative affect and depression and often a need to withdraw from contact with others and even themselves. On an internal level, humans frequently have the need to explain to themselves the events that have just occurred, which may include anger, distorted perceptions, or a genuine plan for recovery. The extreme cases we refer to as psychopathology.
Psychopathology From an Evolutionary Perspective
Psychopathology from an evolutionary perspective goes beyond the traditional psychological and physiological considerations. Considering the evolutionary perspective, we ask additional types of questions. One question might be, how long in terms of our human history has a particular psychopathological disorder existed? As noted in Chapter 1, a WHO study examined the presence of schizophrenia in a number of countries with very different racial and cultural backgrounds (Sartorius et al., 1986). What these authors found was that despite the different cultural and racial backgrounds surveyed, the experience of schizophrenia was remarkably similar across countries. Likewise, the risk of developing schizophrenia was similar in terms of total population presence (about 1%). Further, the disorder had a similar time course in its occurrence, with its characteristics first being seen in young adults.
If you put these facts together, it suggests that schizophrenia is a disorder that has always been part of the human experience. Because it is found throughout the world in strikingly similar ways, this suggests that it existed before humans migrated out of Africa. The genes related