Psychomotor performance and monoamine function in bipolar and unipolar affective disorders

Area of Science:

• Neuroscience
• Psychiatry
• Biochemistry

Background:

• Affective disorders present with significant psychomotor abnormalities.
• These abnormalities may stem from altered catecholamine function affecting arousal and motivation.

Purpose of the Study:

• To investigate the relationship between psychomotor test performance and catecholamine system function.
• To differentiate these relationships in unipolar depression, bipolar disorder (manic, depressive, mixed episodes), and healthy controls.

Main Methods:

• Assessed psychomotor performance using tests of motor speed (reaction time, tapping speed) and visual tracking (trail making, dot placement).
• Measured catecholamine and metabolite concentrations in cerebrospinal fluid (CSF) and urine.
• Included medicine-free inpatients with unipolar depression or bipolar disorder, and age- and gender-matched healthy controls.

Main Results:

• Unipolar and bipolar depressed patients exhibited impairments in motor speed, dexterity, and visual tracking.
• Manic and mixed bipolar patients showed no significant psychomotor differences compared to controls.
• Tapping speed correlated with CSF 3-methoxy-4-hydroxyphenylglycol in controls and CSF homovanillic acid in bipolar depressed subjects.
• Increased catecholamine function was linked to slower psychomotor performance in bipolar disorder patients.
• Psychomotor function correlated with depression severity in bipolar but not unipolar patients.

Conclusions:

• Catecholamine systems are associated with heightened arousal and psychomotor impairment in bipolar disorder.
• The neurotransmitter relationships underlying psychomotor changes differ between unipolar and bipolar disorders.