Perspective

Helen S. Mayberg

Departments of Psychiatry and Medicine (Neurology) and The Rotman Research Institute,

University of Toronto, Toronto, Canada

DIAGNOSTIC AND CLINICAL FEATURES Clinical Nosology

Feeling "depressed" is a common human experience, occurring most often as a normal response to external events or personal loss. A major depressive episode, on the other hand, whether idiopathic or occurring as a part of a defined neurological disorder is a pathological condition, diagnosed not only by the presence of persistent negative mood or anhedonia but also by associated changes in (1) sleep pattern, (2) body weight, and (3) motor and mental speed, with (4) fatigue or loss of energy, (5) poor concentration and apathy, (6) feelings of worthlessness or inappropriate guilt, and (7) recurrent thoughts of death with suicidal ideations or suicide attempts (APA, 1994).

Symptom Dimensions. While these criteria provide a standardized method for ensuring reliable depression diagnoses, they offer little neurobiological context. Toward

Textbook of Biological Psychiatry. Edited by Jaak Panksepp Copyright © 2004 by Wiley-Liss, Inc. ISBN: 0-471-43478-7

this goal, correlative studies examining relationships between behavioral features and specific neurochemical or anatomical systems provide an important perspective. For example, behavioral pharmacology studies have linked disturbances in energy, drive, and impulsivity to general dysfunction of the norepinephrine (NE), dopamine (DA), and serotonin or 5-hydroxytryptamine (5-HT) systems, respectively. In this context, core symptoms of depression would appear to involve multiple and interactive neurochem-ical systems: decreased motivation as a combined NE and DA disturbance (energy + drive), and anxiety and irritability as a change in NE/5-HT (energy + impulsivity). While not all depression symptoms are accommodated by such a biochemical construct, nor are known variations in illness presentation easily explained, this approach has nevertheless, provided an important framework for antidepressant drug development and general treatment strategies (Charney, 1998; Thase et al., 2001).

Alternatively, syndromal features can first be grouped categorically, based on general neurological principles of behavioral localization, with neurochemical dysfunction considered secondarily in context of specific regions and neural pathways (Mesulam, 1985). From this perspective, four behavioral domains appear to capture the principal components of depression: mood, circadian-somatic, cognitive and motor (Fig. 7.1). While this categorical approach is a gross oversimplification, it provides a conceptual framework to examine heterogeneity in clinical presentation as well as targets of antidepressant treatment from an anatomical, physiological, and biochemical perspective. For example, a depressed patient with motor slowness, executive dysfunction, apathy, and inattention is as classic a presentation as one with motor agitation, anxiety, and ruminative guilt. Similarly, typical and atypical patterns of sleep and appetite disturbances (anorexia with insomnia; excessive sleep with overeating) are both common. Despite these apparent contradictions, symptoms can nonetheless be categorized into motor, cognitive, and vegetative/circadian subsystems where mechanisms mediating change in appetite decreased drive decreased libido change in sleep change in weight hopelessness suicidality anxiety low energy dysphoria anhedonia change in appetite decreased drive decreased libido change in sleep change in weight hopelessness suicidality anxiety low energy

poor attention slowed mental speed decreased motivation executive dysfunction ST memory deficits apathy ruminations excessive guilt motor slowing restlessness agitation

Figure 7.1. Depression: Clinical dimensions. DSM-IV diagnostic criteria are reorganized into four principal behavioral domains—mood, cognitive, circadian, and motor—of relevanceto a putative neural systems model of the depression syndrome.

poor attention slowed mental speed decreased motivation executive dysfunction ST memory deficits apathy ruminations excessive guilt motor slowing restlessness agitation

Figure 7.1. Depression: Clinical dimensions. DSM-IV diagnostic criteria are reorganized into four principal behavioral domains—mood, cognitive, circadian, and motor—of relevanceto a putative neural systems model of the depression syndrome.

variations within a behavior domain might be more easily evaluated. This approach is in many ways analogous to that taken with hyperkinetic and hypokinetic movement disorders where variable presentations of motor functioning (e.g., dyskinesias versus bradykinesia) have been linked to different functional states of common neural pathways within the extrapyramidal motor system (Lange and Lozano, 1998). Such an approach has not been systematically applied to the study of depression subtypes using current or previous classification schemas despite experimental evidence that endogenomorphic/melancholic and neurotic-reactive/atypical depressions appear to be clinically and possibly etiologically distinct (Klein, 1974). The potential utility of this approach will be developed throughout this chapter.

Do Not Panic

Do Not Panic

This guide Don't Panic has tips and additional information on what you should do when you are experiencing an anxiety or panic attack. With so much going on in the world today with taking care of your family, working full time, dealing with office politics and other things, you could experience a serious meltdown. All of these things could at one point cause you to stress out and snap.

Get My Free Ebook


Post a comment