Desktop version

Home arrow Psychology arrow 100 questions & answers about depression

What is the DSM-IV-TR?

The DSM-IV-TR (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revised) is considered the standard diagnostic manual for establishing the diagnosis of various mental disorders. Of note, in its introduction a few caveats are outlined. First, mental disorder implies a distinction from physical disorders that is a relic of mind-body dualism. Second, " 'mental disorder' lacks a consistent operational definition that covers all situations." Third, the categorical approach has limitations in that discrete entities are assumed when in fact there are no absolute boundaries dividing one disorder from another. Fourth, the criteria for each disorder serve as guidelines only and should not be applied in either a "cookbook fashion" or in an "excessively flexible" manner. Finally, the purpose of the manual is primarily to enhance agreement among clinicians and investigators and is not to imply that any "condition meets legal or other non-medical criteria for what constitutes mental disease, mental disorder, or mental disability" (see Introduction and Cautionary Statement of DSM-IV-TR).

It is critical to keep these caveats in mind, because it is easy to get caught in a physician's diagnosis, believing that it is set in stone, which it is not. As new information is acquired in treatment, the diagnosis and treatment plan may change. Additionally, it is not uncommon for clinicians to disagree on the diagnosis because of the previously mentioned caveats. When reading the various criteria individually, it is easy to identify with many of them and jump to the conclusion that one has the described condition. Only time and the guidance of a skilled clinician who is probing and comprehensive in his or her questioning will help to establish a diagnosis that leads to an effective treatment plan[1]. The ability to establish a diagnosis is important in developing a treatment plan that restores one's health; if the treatment plan fails, the first order of business is to reconsider the diagnosis.

How do chemicals work in the brain?

The brain is a complex organ comprising gray matter and white matter. Gray matter[2] consists of the cell bodies of neurons and other support cells, and white matter[3] consists of long tracts of axons that run between the neurons. Figure 1 shows an illustration of a neuron. Different areas of the brain have somewhat specific functions. For example, the motor cortex[4] controls voluntary movements of the body, and the sensory cortex processes information to the senses. Different areas of the brain communicate with other areas nearby as well as more distantly. Information travels via the axons of the neurons[5] within the white matter areas of the brain.

Figure 1

The brain contains billions of neurons that interact with each other electrochemically[6]. This means that when a nerve is stimulated, a series of chemical events occur that in turn create an electrical impulse. The resulting impulse propagates down the nerve length known as the axon[7] and causes a release of chemicals called neurotransmitters[8] into a space between the stimulated nerve and the nerve that it wishes to communicate with, known as the synaptic cleft[9] (Figure 2). The neurotransmitters interact with receptors on the second nerve, either stimulating or inhibiting them. The interaction between the neurotransmitters and receptors can be likened to a key interacting with a lock where the neurotransmitter, or "key," engages the receptor[10], or "lock," causing it to "open." This opening is really a series of chemical changes within the second nerve that either causes that nerve to "fire" or "not fire." Thus brain activity is the result of an orchestrated series of nerves firing or not firing in a binary fashion. In that sense it is much like a computer where very complicated processes begin their lives as a series of 1s or 0s (on or off, fire or do not fire).

After the nerve fires, thereby releasing neurotransmitters into the synaptic cleft, the neurotransmitters must be removed from the area to turn the signal off. There are two ways that these chemicals can be removed to turn the signal off. The first is by destroying the chemical through the use of another chemical, known as an enzyme[11], with that specific purpose in mind. The second is by pumping the chemical back into the nerve that released it by using another special chemical known as a transporter or transport pump. The process of pumping chemicals back into the nerve is known as reuptake (Figure 2). It is important to understand these

The interaction between the neurotransmitters and receptors can be likened to a key interacting with a lock where the neurotransmitter, or "key," engages the receptor, or "lock," causing it to "open."

Figure 2

basic principals of neurophysiology because all psycho-active compounds, whether neurotransmitters, hormones, medications, or addictive drugs, involve one or more of these simple mechanisms.

  • [1] the plan agreed on by patient and clinician that will be implemented to treat a mental illness. It incorporates all modalities (therapy and medication).
  • [2] the part of the brain that contains the nerve cell bodies, including the cell nucleus and its metabolic machinery, as opposed to the axons, which are essentially the "transmission wires" of the nerve cell. The cerebral cortex contains gray matter.
  • [3] tracts in the brain that consist of sheaths (called myelin) covering long nerve fibers.
  • [4] portion of the cerebral cortex that is directly related to voluntary movement. Also known as the motor strip, its anatomy correlates accurately with specific bodily movements, such as moving the left upper or lower extremities.
  • [5] a nerve cell made up of a cell body with extensions called the dendrites and the axon. The dendrites carry messages from the synapse to the cell body, and the axon carries messages to the synapse to communicate with other nerve cells.
  • [6] the mechanism by which signals are transmitted neurologically. Brain chemicals, or neurotransmitters, alter the electrical conductivity of nerve tissue, causing a signal to be transmitted or sent.
  • [7] a single fiber of a nerve cell through which a message is sent via an electrical impulse to a receiving neuron. Each nerve cell has one axon.
  • [8] chemical in the brain that is released by nerve cells to send a message to other cells via the cell receptors.
  • [9] the junction between two neurons where neurotransmitters are released, resulting in the communication of a message between the two neurons.
  • [10] a protein on a cell on which specific chemicals from within the body or from the environment bind to cause changes in the cell that result in an electrochemical message for a certain action to be taken by that cell.
  • [11] a protein made in the body that serves to break down or create other molecules. Enzymes serve as catalysts to biochemical reactions in the body.
< Prev   CONTENTS   Next >

Related topics