kolbintro5e

Chapter Introduction

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CHAPTER 16

What Happens When the Brain Misbehaves?

RESEARCH FOCUS 16-1 POSTTRAUMATIC STRESS DISORDER

16-1 MULTIDISCIPLINARY RESEARCH ON BRAIN AND BEHAVIORAL DISORDERS

CAUSES OF DISORDERED BEHAVIOR

INVESTIGATING THE NEUROBIOLOGY OF BEHAVIORAL DISORDERS

16-2 CLASSIFYING AND TREATING BRAIN AND BEHAVIORAL DISORDERS

IDENTIFYING AND CLASSIFYING BEHAVIORAL DISORDERS

TREATMENTS FOR DISORDERS

RESEARCH FOCUS 16-2 TREATING BEHAVIORAL DISORDERS WITH TRANSCRANIAL MAGNETIC STIMULATION

16-3 UNDERSTANDING AND TREATING NEUROLOGICAL DISORDERS

TRAUMATIC BRAIN INJURY

CLINICAL FOCUS 16-3 CONCUSSION

STROKE

EPILEPSY

MULTIPLE SCLEROSIS

NEURODEGENERATIVE DISORDERS

ARE ALL DEGENERATIVE DEMENTIAS ASPECTS OF A SINGLE DISEASE?

AGE-RELATED COGNITIVE LOSS

16-4 UNDERSTANDING AND TREATING PSYCHIATRIC DISORDERS

SCHIZOPHRENIA SPECTRUM AND OTHER PSYCHOTIC DISORDERS

MOOD DISORDERS

RESEARCH FOCUS 16-4 ANTIDEPRESSANT ACTION AND BRAIN REPAIR

ANXIETY DISORDERS

16-5 IS MISBEHAVIOR ALWAYS BAD?

Katherine Streeter

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RESEARCH FOCUS 16-1

Posttraumatic Stress Disorder

Life is filled with stress. Routinely, we cope. But some events are so physically threatening and often emotionally shattering that long-term consequences ensue. Flashbacks and nightmares persist long after any physical danger has passed. These symptoms can lead to emotional numbness and a diagnosis of posttraumatic stress disorder, or PTSD (Jorge, 2015).

Traumatic events that may trigger PTSD include violent assault, natural or human-caused disaster, accident, and war. An estimated 1 in 6 veterans of the conflicts in Iraq and Afghanistan, many not directly exposed to combat, developed symptoms of PTSD, including intrusive, unwanted thoughts; avoiding thoughts related to stressful events; negative cognitions and moods; and altered arousal and reactivity responses. Understanding the neural basis and identifying new PTSD treatments has spurred intense interest. Nevertheless, treatment is often difficult, and most sufferers receive no or little treatment.

That a beneficial therapy is to relive a traumatic event is counterintuitive. Yet in virtual reality (VR) exposure therapy, a controlled virtual immersion environment combines realistic street scenes, sounds, and odors that allow people to relive traumatic events (Gonçalves et al., 2012). The Virtual Iraq and Afghanistan Simulation is customized for war veterans to start with benign events—such as children playing—and gradually add increasingly stressful components, culminating in such traumatic events as a roadside bomb exploding in the virtual space around an armored personnel carrier, illustrated here.

To make Virtual Iraq realistic, the system pumps in smells, stepping up from the scent of bread baking to body odor to the reek of gunpowder and burning rubber. Speakers provide sounds while off-the-shelf subwoofers mounted under the subject’s chair re-create movements. VR exposure therapy is now used prior to stress exposure for soldiers, police, firefighters, and other first responders, as a means of preventing PTSD (Rizzo et al., 2012).

Courtesy Albert “Skip” Rizzo, Ph.D., USC-ICT

Many unknowns related to PTSD remain, including how stress injures the brain, especially the frontal lobes and hippocampus (Wingenfeld & Wolf, 2014); why some people do not develop PTSD following extremely stressful events; and the extent to which PTSD is associated with other health events, including previous stressors, diabetes, and head trauma (Costanzo et al., 2014). That said, assessment and treatment options for most of those who endure PTSD are poor: over half of all war veterans, for example, receive no assessment or treatment.

Current understanding of PTSD illustrates how thinking on the brain’s role in health can shift. Largely as a result of symptoms displayed by returning Vietnam War veterans, in 1980 the DSM-III introduced PTSD as a mental disorder. Lynda Holmstrom and Ann Burgess (1978) as well pointed out similarities in symptoms between war veterans and rape victims.

A prominent feature of PTSD diagnosis is that a traumatic external agent, rather than internal causes, is prominent in producing the characteristic set of behavioral symptoms described in Research Focus 16-1, Posttraumatic Stress Disorder. Neuroscientists now recognize that the brain contributes to PTSD development and that traumatic experiences related to policing, firefighting, and accidental events can contribute to the condition.

The many discussions of behavioral disorders and organic disease presented throughout this book serve both to illustrate the brain’s organization and functioning and to exemplify how knowledge about brain function contributes to understanding and treating brain disorder and disease. Classifying and treating organic and behavioral conditions is our focus in this chapter.

We know that the brain is complex. We do not yet understand all its parts and their functions, nor is it clear how the brain produces mind, a sense of well-being, and a sense of self. Still, significant advances have led to the realization that while under some circumstances the brain copes competently with life’s challenges, under other circumstances, it is not up to the job.

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To illustrate progress in studying brain and behavior over the past century, we can contrast the theories of Sigmund Freud with present-day views. Freud’s theories were based on his observations of patients while not having the help of the anatomical or imaging data available today. The underlying tenet of Freud’s theory is that our motivations are largely hidden away in our unconscious mind. Freud posited that a mysterious, repressive force actively withholds our sexual and aggressive motivations from conscious awareness. He believed that mental illness resulted from the failure of these repressive processes.

Freud proposed the three components of mind illustrated in Figure 16-1A:

Primitive functions, including the “instinctual drives” of sex and aggression, arise from the id, the part of the mind that Freud thought operated on an unconscious level.
The rational part of the mind he called the ego. Freud also believed, much of the ego’s activity to be unconscious, although experience (to him, perceptions of the world) is conscious.
The superego aspect of mind acts to repress the id and to mediate ongoing interactions between the ego and the id.

Figure 16-1: FIGURE 16-1 Mind Models (A) Freud based his model of the mind, drawn in 1933, solely on clinical observations (color added). (B) In a contemporary brain imaging and lesioning studies map, the brainstem and limbic system correlate with Freud’s depiction of the id, the ventral frontal and posterior cortex with the ego, and the dorsal frontal cortex with the superego.

Information from a drawing by Mark Solms and Oliver Turnbull.

For Freudians, abnormal behaviors result from the emergence of unconscious drives into voluntary conscious behavior. The aim of psychoanalysis, the original talk therapy, is to trace symptoms to their unconscious roots and thus expose them to rational judgment.

By the 1970s, scientific studies of the brain made the whole notion of id, ego, and superego seem antiquated. Nevertheless, some resemblance between Freud’s theory and brain theory is apparent (Figure 16-1B). The limbic system and brainstem have properties akin to those of the id: they produce emotional and motivated behavior, including the will to survive and to reproduce. The posterior and the dorsolateral frontal cortices have properties akin to those of the ego: they allow us to learn and to solve everyday problems. The prefrontal neocortex has properties akin to those of the superego, enabling us to be aware of others and to learn to follow social norms. Furthermore, as abundantly displayed in earlier chapters, many processes underlying these functions are unconscious: they operate outside our awareness.

Three differences between Freud’s view and present-day neuroscience are apparent. First, we now recognize that the brain is composed of hundreds of interacting structures, not just three. Second, we know that the functions of these brain parts is complicated and depends upon ongoing expression of genes, interactions of myriad chemicals, and functioning and connections of glia and neurons. Third, we understand that behavioral disorders have complex causes, including genetic abnormalities, abnormalities in nervous system development over the life-span, and environmental and epigenetic effects that modulate genetic and developmental expression.

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Investigating the origins and treatment of disordered behavior is perhaps the most fascinating pursuit in studying the brain and behavior. Once, neurologists treated organic disorders of the nervous system—conditions such as Parkinson disease and stroke—medically. Psychiatrists treated mental disorders such as schizophrenia and PTSD pharmacologically. Psychological disorders were treated with counseling and other behavioral therapies. Increasingly, practitioners are synthesizing their insights into a unified understanding of mind and brain, a neuropsychoanalysis that views the brain as the ultimate source of behavior. When loved ones develop brain disorders, family members usually become the primary caregivers and as such join practitioners as participants, because they and their loved ones are those most affected.

With this synthesis of understanding about brain and behavior in mind, we first survey how researchers investigate the neurobiology of organic and behavioral disorders. We then examine how disorders are classified, treated, and distributed in the population and review established and emerging treatments both for neurological and for psychiatric disorders.