What are Mood Disorders?

Mood disorders are illnesses that are categorized by uncontrollable mood changes. According to the DSM IV TR (Diagnostic and Statistical Manual of Mental Disorders), mood disorders are identified when the disturbance in a person's mood is the main, underlying feature. 

Mood disorders are very dangerous because they often start at an early age, but are difficult to diagnose in youth.

Mood disorders also have a very high suicide rate. 

Types of Mood Disorders:

Depression

• Major Depressive Disorder
• Dysthymic Disorder

Bipolar Disorder

• Bipolar I
• Bipolar II
• Cyclothymia

Statistics on Mood Disorders

• 20% of the US adult population has been diagnosed with a mood disorder
• Women are 50% more likely than men to experience a mood disorder
• Mood disorders often occur with anxiety disorders and substance abuse
• 90% of suicides can be traced back to a mood disorder

Mood Disorders in Adults

 http://www.nimh.nih.gov/statistics/images/NCS-R_MoodDisorders-Chart1-360.jpg

Mood Disorders in adults by Age

http://www.nimh.nih.gov/statistics/images/NCS-R_MoodDisorders-Chart2-360.jpg

 

Mood Disorders in Children

www.nimh.nih.gov/statistics/images/NCS-A_data-AnyMoodDisoder-720.jpg

 

Neurobiology of Mood Disorders

Mood Disorders are recurrent because of abnormal brain development, which is caused by a combination of genetic, developmental and environmental factors.

Neurobiology of emotions:  

Many parts of the brain are involved in emotions, which are largely related to mood disorders. The majors players in regulating emotions are the hypothalamus, cingulate and prefrontal cortexes, and  the amygdala.

• The hypothalamus controls somatic, autonomic and endocrine responses. 
• The cingulate and prefrontal cortex are responsible for conscious emotional experience.
• The amygdala helps to coordinate the conscious experience of emotion and peripheral expressions of emotion. Emotional conditioning is a part of implicit memory. 

www.brainwaves.com/images/brain-basic_and_limbic.gif

• Papez's circuit diagrams the interactions in the brain that induce emotion, which is displayed below. 

www.acupuncturecourse.org.uk/acupuncture/articles/papez.jpg

• Hypothalamus=coordinates the autonomic and somatic responses to emotional stimuli
• Amygdala= amygdala is very important in recollection of specific emotional events, this has been shown in EEG recordings. Amygdala has also been shown to be linked to emotional responses of fear and anxiety. Also recognition of emotional expressions involves the amygdala. This is seen in the 1999 study of amygdala activation upon hearing "threatening" words. The brain scan below depicts this amygdala activation to "threatening words".

www. pnas.org/context/96/18/10456/F2/small.gif

• Also impaired amygdala has shown to impair the ability recognize facial expressions

www.lauracanderson.blogspot.com/2011/02/recognition-of-facial-emotion-in-nine.html

• Amygdala also  has been shown to be important for pleasurable responses.
• Amygdala mediates both the autonomic expression and cognitive experience of emotion→sends projections to hypothalamus and sends projections to the cingulate and prefrontal cortices. 

Genetic Polymorphism: a functional polymorphism is a genetic variant that alters the biological functioning of the individual and is seen in at least 1% of the population. Genetic polymorphisms are believed to play a large role in the development of mood disorders.

Types of polymorphisms seen in Mood Disorders:

• Serotonin transporter:
• Serotonin 2A receptor
• MTHF reductase
• Catachol-o-methyl transferase (COMT)
• Tyrosine hydroxylase
• Cytochrome P450 metabolism of medications