Anhedonia is the loss of the capacity to experience pleasure (loss of joy).  Specifically, it is the inability to gain pleasure from normally pleasurable experiences.  It is sometimes described as "flat mood".  It is derived from Greek "an-" (without) and "hedone” (pleasure, delight).  Neurophysiologists think that anhedonia may result from a breakdown of the brain’s reward system, involving dopamine pathways.

In 2005 the Institute of Psychiatry in London used fMRI to compare 12 people with anhedonia and depression to 12 healthy individuals.  They identified three areas of the brain that worked differently:

•  The ventromedial prefrontal cortex: the front portion of the brain associated with empathy and regulation of negative emotions

• The ventral striatum: the area of the brain signals reward

• The amygdala: an almond shaped area of the brain that has a primary role in memory and emotional regulation. 

All three of these areas of the brain are involved in reactions to sad and happy stimuli.  In individuals with anhedonia, the prefrontal cortex had to work harder to register happiness, and there was less activity in the amygdala and striatum.  

Depressed mood, fatigue, and loss of energy are hallmark symptoms of anhedonia.  Anhedonia is a key feature noted in several mental disorders including depression and schizophrenia.  Anhedonia is often an early sign of progression toward clinical depression.  Gradual withdrawal into isolation and indifference are often seen in this phase. This can mistakenly be viewed by others as laziness, but it is really a closing down of the world in that individual’s perception of life.  As pleasure is lost in ordinary activities, a person may begin to constrict the number of activities they choose to participate in. This condition can place great strains on relationships and it usually is accompanied by a loss of sex drive. Anhedonia is often experienced by drug addicts after detoxification or withdrawal off of addictive drugs or alcohol.  This loss of pleasure becomes one of the driving forces behind addiction.  The addict desperately wants to feel exhilaration and pleasure once again. Addictions to drugs that are stimulants, such as cocaine or amphetamines, produce a higher incidence of anhedonia following withdrawal than other drugs.  Research has demonstrated that certain long-term addicts will experience protracted or permanent breakdown in the pleasure pathways in the brain and can lead to long-term symptoms of anhedonia.  In most cases though, extended periods of abstinence from addictive drugs (and alcohol) combined with a good substance dependence recovery plan and a healthy lifestyle and reverse these symptoms.