Persistent Depressive Disorder (PDD) is a chronic form of depression that can consist of a two-year or longer period of major depressive episode, or a lower-level depressive presentation that used to be known as dysthymic disorder. I believe that quite a number of the ADHD therapy clients I see meet the criteria for the dysthymic presentation of PDD, although I've yet to meet one that tells me they have been given this diagnosis as an explanation of their chronic depressed mood.
The Dysthymic Mood Variant
The dysthymic mood variant of PDD is distinguished by lower-level ongoing depressive symptoms for at least two years. People with dysthymic PDD often describe their mood as a constant state of gloom or sadness that becomes a part of their daily life and can last for many years, sometimes decades. This pervasive low mood can significantly impact a person's quality of life, even if it doesn't reach the intensity of a major depressive episode (although many people with a dysthymic mood will dip in and out of periods of major depression).
Understanding Mood States
To grasp the syndrome of Persistent Depressive Disorder, it is helpful to understand the spectrum of mood states that individuals may experience from lowest to highest mood.
Major Depressive Episode: Characterised by five or more of a list of nine depressive symptoms that significantly impact daily functioning for two or more weeks. Symptoms can include intense sadness, loss of interest in activities, changes in appetite and sleep patterns, and thoughts of suicide. If the episode lasts for at least two years, it can be classified as Pervasive Depressive Disorder, which used to be called Chronic Depression.
Dysthymic Mood: A chronic form of depression with at least two depressive symptoms that significantly impact daily functioning for at least two years.
Euthymia: Refers to a stable mental state or mood that is neither excessively elevated nor depressed. It represents a baseline of "normal" functioning and emotional balance. In psychology, this is the mood state we want our clients to be in most of the time.
Hypomanic Episode: A milder form of mania characterised by elevated mood, increased activity or energy levels, reduced need for sleep, and often heightened creativity or productivity for at least four days. Unlike mania, hypomania does not cause severe impairment in social or occupational functioning.
Manic Episode: A state of abnormally elevated mood, energy, and activity levels for at least one week. It can include impulsive behaviour, rapid speech, decreased need for sleep, and grandiosity. Mania significantly impairs daily functioning and often requires medical intervention. If admitted to hospital, then mania is evident, irrespective of the duration of symptoms.
Mixed Mood State: Involves the simultaneous occurrence of symptoms of both mania (or hypomania) and depression. Individuals may experience high energy, agitation, or racing thoughts while simultaneously feeling sad, hopeless, or irritable, leading to significant emotional instability and distress.
Symptoms of Dysthymic PDD
According to the Diagnostic and Statistical Manual of Mental Disorders (DSM5), individuals with the dysthymic variant of PDD much experience two (or more) of the following symptoms:
Depressed mood for most of the day, for more days than not
Poor appetite or overeating
Insomnia or hypersomnia (difficulty sleeping or sleeping too much)
Low energy or fatigue
Low self-esteem
Poor concentration or difficulty making decisions
Feelings of hopelessness
These symptoms must be present for at least two years in adults (one year in children and adolescents) to meet the diagnostic criteria, with an absence of symptoms for no more than two months in that time period.
Impact on Daily Life
The chronic nature of dysthymic PDD means that individuals often struggle with its effects for extended periods. This can lead to difficulties in maintaining employment, forming and sustaining relationships, and achieving personal goals. The constant presence of low mood can also reduce motivation and enjoyment in activities, further impacting one's mental health. PDD might be missed for diagnosis as it's effects are not as severe as a major depressive episode, or it may simply be described as depression.
Treatment and Management
Several treatment options can help manage symptoms effectively, which are all pretty much the same as for a major depressive episode:
Psychotherapy: Cognitive-behavioural and related therapies.
Medication: Antidepressants may be helpful, as with major depression.
Lifestyle Changes: Regular physical activity, a balanced diet, and proper sleep practices can significantly impact mood and energy levels.
Support Systems: Building a robust support network, whether through support groups, family, or friends, can provide essential emotional support and encouragement.
Conclusion
The dysthymic variant of PDD is a chronic but treatable condition once it is recognised as present. I see many clients with years worth of depressed mood, some who have not received treatment, and some who could do with going back to their GP to discuss the effectiveness of the antidepressant they are taking.
For further details about depressive mood disorders, this ADDitude article provides a summary.
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