PubMed2005
BACKGROUND AND STUDY PURPOSE: Pain and depression share similar neurobiological characteristics, and it is a common clinical observation that pain and depression may coincide in the same patient. They also appear to influence each other in the process of chronification. Furthermore, there is a complex coupling of pain and depression by monoaminergic transmitter system. PATIENTS AND METHODS: On the basis of these findings, norepinephrine (NE), epinephrine (E), dopamine (DOP), 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and vanillylmandelic acid (VMA) concentrations were determined in the cerebrospinal fluid (CSF) in patients with acute (20), chronic (27), and episodic pain syndrome (44) in a prospective study. The biochemical parameters were correlated to self-assessment pain and depression scores. The control group consisted of 13 pain-free patients with diseases affecting the muscular system. RESULTS: Patients with chronic and episodic pain syndromes had significantly more depressive and psychovegetative symptoms compared to patients with acute pain. In patients with acute pain, DOP was significantly higher than in controls and chronic and episodic pain patients. In addition DOP was positively correlated to self-assessment pain score (p*<0.05). In patients with chronic and episodic pain, NE and 5-HIAA were positively correlated to the duration of disease and were significantly lower than in the control group. In neither of these two groups could significant correlations be established between these parameters and pain or depression self-assessment scores. In all groups, positive correlations were seen between the neurotransmitter and their metabolites. CONCLUSION: The pathological decrease of NE and 5-HIAA in the CSF points to the crucial role of noradrenergic and serotonergic transmitter systems in the generation, modulation, and perpetuation of chronic and episodic pain syndromes. It indicates that antidepressants are effective drugs in these diseases. However, a discriminative neurochemical pattern between pain and depression could not be established. The demonstration of polyvalent correlations between different neurotransmitters is indicative of complex neurobiological coupling between cortical, limbic, and hypothalamic neuronal networks on the one hand and the nociceptive descending system on the other hand in the genesis of pain and depression.