Plasma dopamine beta hydroxylase activity in affective disorders

Area of Science:

• Neuroscience
• Psychiatry
• Genetics

Background:

• Affective disorders encompass a range of mood disorders.
• Dopamine beta hydroxylase (DBH) is an enzyme involved in neurotransmitter synthesis.
• DBH activity has been investigated as a potential biomarker for psychiatric conditions.

Purpose of the Study:

• To investigate the relationship between plasma dopamine beta hydroxylase (DBH) activity and affective disorders.
• To determine if plasma DBH activity is influenced by illness status, medication, or environmental factors.
• To explore the genetic heritability of plasma DBH activity.

Main Methods:

• Plasma DBH activity was measured in patients diagnosed with affective disorders and their healthy relatives.
• Comparative analyses were performed between patient groups (unipolar vs. bipolar) and treatment conditions (lithium vs. placebo).
• Exercise challenges at different temperatures were used to assess dynamic DBH activity responses.
• Familial studies included monozygotic and dizygotic twins, as well as same-sex siblings, all discordant for affective illness.

Main Results:

• No significant differences in resting plasma DBH activity were observed between unipolar and bipolar patients, or between those receiving lithium versus placebo.
• Exercise elicited distinct plasma DBH activity response patterns in patients compared to controls.
• Plasma DBH activity showed high concordance in monozygotic twins and significant similarity in dizygotic twins, even when discordant for affective illness.
• Remarkable similarity in plasma DBH activity was found in same-sex siblings also discordant for affective illness.

Conclusions:

• Resting plasma dopamine beta hydroxylase (DBH) activity is not directly associated with the presence of affective disorders.
• Plasma DBH activity is predominantly determined by genetic factors, as evidenced by twin and sibling studies.
• These findings suggest that DBH activity may not serve as a reliable diagnostic marker for affective disorders in their resting state.