Caffeine,as an important component of refreshment beverage,has been used for a long history. In recent years,its effect on pain relief has been widely explored. As one of nonselective adenosine receptor blockers,caffeine plays different roles in the central and peripheral pain. This review explores the roles of caffeine in acute and chronic pain and the potential mechanisms.
Adenosine ; antagonists & inhibitors ; metabolism ; Caffeine ; pharmacology ; therapeutic use ; Central Nervous System Stimulants ; pharmacology ; therapeutic use ; Chronic Pain ; drug therapy ; Humans ; Pain ; drug therapy

PURPOSE: The aim of this study was to clarify the relationship between the autonomic nervous system and attention deficit hyperactivity disorder (ADHD) rating scales and to evaluate the usefulness of heart rate variability (HRV) as a psychophysiological biomarker for ADHD. MATERIALS AND METHODS: Subjects were recruited from outpatients in the Department of Child and Adolescent Psychiatry at the Korea University Medical Center from August 2007 to December 2010. Subjects received methylphenidate. Time- and frequency-domain analyses of HRV, the Korean ADHD rating scale (K-ARS), and computerized ADHD diagnostic system were evaluated before treatment. After a 12-week period of medication administration, we repeated the HRV measurements and K-ARS rating. RESULTS: Eighty-six subjects were initially enrolled and 37 participants completed the 12-week treatment and HRV measurements subsequent to the treatment. Significant correlations were found between the K-ARS inattention score and some HRV parameters. All of the HRV parameters, except the standard deviations of the normal-to-normal interval, very low frequency, and low frequency to high frequency, showed a significant positive correlation between baseline and endpoint measures in completers. High frequency (HF) and the square root of the mean squared differences of successive normal-to-normal intervals (RMSSD), which are related to parasympathetic vagal tone, showed significant decreases from baseline to endpoint. CONCLUSION: The HRV test was shown to be reproducible. The decrease in HF and RMSSD suggests that parasympathetic dominance in ADHD can be altered by methylphenidate treatment. It also shows the possibility that HRV parameters can be used as psychophysiological markers in the treatment of ADHD.
Adolescent ; Attention/drug effects/*physiology ; Attention Deficit Disorder with Hyperactivity/diagnosis/*drug therapy ; Autonomic Nervous System/physiopathology ; Biomarkers ; Central Nervous System Stimulants/pharmacology/*therapeutic use ; Child ; Female ; Heart Rate/*drug effects/physiology ; Humans ; Male ; Methylphenidate/pharmacology/*therapeutic use ; Prospective Studies ; Republic of Korea ; Treatment Outcome

The regional cerebral blood flow (rCBF) responses to methylphenidate (MPH) treatment were examined in children with attention deficit/hyperactivity disorder (ADHD). Thirty-two male children, diagnosed with ADHD by the DSM-IV diagnostic criteria, other behavioral assessment scales and neuropsychological battery, were studied using 99mTc-HMPAO-single photon emission computed tomography (SPECT). Subjects were studied before and after MPH treatment. First, using an image subtraction method, we obtained a NDR parametric image of each patient and found increased cerebral blood flow in the frontal lobes, caudate nuclei and thalamic areas after treatment. When the changes in SPECT and clinical response were compared, the matching rate, sensitivity and specificity between them were found to be 77.1, 80.0 and 79.2%, respectively. Second, three transaxial brain slices delineating anatomically defined regions of interest (ROI) at 20, 40, and 60mm above the orbitomeatal line (OML) were used, with the average number of counts for each region of interest normalized to the area of the cerebellar maximal uptake. The left and right prefrontal areas, and caudate and thalamic areas showed significant increases in rCBF after MPH treatment. These findings suggested MPH could affect the function of the fronto-striato-thalamic circuit, which is known as the pathophysiologic site of ADHD and could be used to correct the underlying brain dysfunction of ADHD.
Adolescence ; Attention Deficit Disorder with Hyperactivity/radionuclide imaging ; Attention Deficit Disorder with Hyperactivity/physiopathology ; Attention Deficit Disorder with Hyperactivity/drug therapy* ; Central Nervous System Stimulants/pharmacology* ; Cerebrovascular Circulation/drug effects* ; Child ; Female ; Human ; Male ; Methylphenidate/therapeutic use ; Methylphenidate/pharmacology* ; Tomography, Emission-Computed, Single-Photon