•+Depression+and+the+Brain

The nature of depression is believed to be multicausal (Centre for Applied Research in Mental Health and Addiction (CARMHA) and BC Mental Health and Addiction Services (BCMHAS), 2009); see Figure 2.

Figure 2.

**Psychological Theories of Depression** • The **Psychoanalytic theory of depression**, popularized by Sigmund Freud (1917/1950, as cited in Davison et al., 2005), suggests that the potential for depression begins in childhood. If the child's needs during the oral stage are insufficiently or excessively gratified, they become fixated at this stage, and become dependent on the instinctual gratifications linked with the stage (Davison et al.). Thus, the individual may become dependent on other people for the maintenance of self-esteem (Davison et al.). Freud linked this concept with depression in the following way: when an individual loses a loved one, they first identify with the lost person (Davison et al.). Then, because we unconsciously hold negative feelings toward loved ones, the individual becomes angry with themselves, resents being deserted by the loved one, and feels guilt for real or imagines sins committed against the loved one (Davison et al.). When the process of mourning goes awry, the individual ends up in a process of self-abuse, self-blame, and depression, because they continue to direct their anger toward the lost loved one inward (Davison et al.).

• **Cognitive** **theories of depression** can be divided into Beck's theory of depression and helplessness/hopelessness theories. >
 * __Beck's theory of depression__ states that depression is a result of thinking that is biased toward negative interpretations (Davison et al., 2005). During childhood and adolescence, individuals develop a negative schema (worldview) as a result of the loss of a parent, relentless tragedies, social rejection, criticism, or the depressive attitude of a parent (Davison et al.). The negative schemata of depressed individuals are activated when they encounter new situations that resemble the situations in which they learned the schemata (Davison et al.), and these negative schemata are encouraged by cognitive biases.
 * __Helplessness/hopelessness theories of depression __ are further divided into three sub-theories.
 * Learned helplessness theory states "...that an individual's passivity and sense of being unable to act and to control his or her own life is acquired through unpleasant experiences and traumas that the individual tried unsuccessfully to control" (Davison et al., 2005, p.295). The idea is that individuals who have experienced learned helplessness will fail to initiate effective coping strategies in the face of stress (Davison et al.).
 * Attribution and learned helplessness theory suggests that "...people become depressed when they attribute negative life events to stable and global causes", such as a belief that one is unintelligent, or a belief that all tests (i.e., in an educational setting) are unfair (Davison et al.).
 * Hopelessness theory states that depression is caused by the attribution of negative events to stable and global causes, with the additional factors of low self-esteem and a tendency to believe that negative life events will have major negative consequences (Davison et al.).

• **Interpersonal theories of depression** state that individuals who are depressed "...tend to have sparse social networks and to regard them as providing little support" (Davison et al., 2005, p. 297). Reduced social support may diminish the individual's ability to cope with negative life events, and may increase their vulnerability to depression (Billings, Cronkite, & Moos, 1983, as cited in Davison et al., 2005). Individuals who are depressed also tend to elicit negative reactions from other people (Coyne, 1976, as cited in Davison et al., 2005), and this may result in a problem of circular causality, where negative reactions from others leads to alienation and a diminished social network, causing more depression in the individual, which fuels more alienation from others after interacting with the individual.

**Biological Theories of Depression** • The two most-studied neurotransmitters thought to play a role in depression are norepinephrine and serotonin (Davison et al., 2005). The idea is that low levels of norepinephrine and serotonin are linked to depression (Davison et al.).

• In addition to neurotransmitters, the hypothalamic-pituitary-adrenocortical axis may also play a role in depression (Davison et al., 2005). Levels of cortisol, an adrenocortical hormone, are high in depressed individuals, which may be the result of oversecretion of thyrotropin-releasing hormone by the hypothalamus (Garbutt et al., 1994, as cited in Davison et al., 2005). Disorders of thyroid functioning are also seen in many individuals with bipolar disorder (Goodwin & Jamieson, 1990, as cited in Davison et al., 2005).

• The brain's hemispheres are affected differently by depression; symptoms of indifference and flat affect are linked with dysfunction of the right hemisphere, and more-over symptoms of agitation and sadness are linked with dysfunction of the left hemisphere (Davison et al., 2005).

<span style="font-family: Tahoma,Geneva,sans-serif;">**Studies** <span style="font-family: Tahoma,Geneva,sans-serif;">• Gorwood, Corruble, Falissard, and Goodwin (2008) conducted a study of memory in individuals with major depression, in France. 8,229 outpatients were tested for delayed recall, which is a function of memory that is related to the integrity of the hippocampus (Gorwood et al.). Participation was divided into two sessions, several weeks apart (Gorwood et al.). During the testing, participants were read a story by a clinician, and then were asked to repeat the story using as many of the same words that they could recall (Gorwood et al.). After this task, participants were asked to complete the Hospital Anxiety and Depression Scale (a self-report scale) and provide other information; this would last at least 10 minutes (Gorwood et al.). Next, the participants were asked to recall the story again, and the clinician kept score for the stories and the immediate and delayed recall tasks (Gorwood et al.). Gorwood et al. found that the intensity of the participants' current depression was the largest factor in determining their performance on the recall tasks, as opposed to the intensity (number and length) of previous depressive history.

<span style="font-family: Tahoma,Geneva,sans-serif;">However, Gorwood et al. (2008) also found that during follow-up, after significant clinical response, the intensity of previous depressive history was more significant than current symptoms. Gorwood et al. (2008) posited that anxiety (and not just depression) may be playing a role in influencing limbic anatomy, and that since anxiety and depression were highly interconnected in their sample of participants, the possible effect of anxiety on memory must be considered as well.

<span style="font-family: Tahoma,Geneva,sans-serif;">• Another study linking brain function and depression was conducted by Gaffrey, Luby, Belden, Hirshberg, Volsch and Barch (2011). Previous research had indicated that the severity of the symptoms of depression were related to the reactivity in the amygdala when facial expressions of emotion were viewed (Gaffrey et al.). In their study, which they assert to be the first to directly examine brain function in depressed preschoolers, Gaffrey et al. examined the results of fMRI scans of 11 depressed preschoolers; the children viewed facial expressions of emotion during the scans. They found that when viewing facial expressions of negative affect, depressed preschoolers demonstrated a significant positive correlation between depression severity and right amygdala activity (Gaffrey et al.). They also found a significant positive correlation between depression severity and degree of functional activation in the occipital cortex while viewing faces (Gaffrey et al.).

<span style="font-family: Tahoma,Geneva,sans-serif;">However, Gaffrey et al. (2011) acknowledged that a larger sample and the use of a healthy control group is needed in future studies to replicate their findings and analyze their specificity in children of this age group.