DHA mediates the protective effect of fish consumption on new episodes of depression among women.

In a longitudinal cohort study of young Australian adults, we reported that for women higher baseline levels of fish consumption were associated with reduced incidence of new depressive episodes during the 5-year follow-up. Fish are high in both n-3 fatty acids and tyrosine. In this study, we seek to determine whether n-3 fatty acids or tyrosine explain the observed association. During 2004-2006, a FFQ (nine fish items) was used to estimate weekly fish consumption among 546 women aged 26-36 years. A fasting blood sample was taken and high-throughput NMR spectroscopy was used to measure 233 metabolites, including serum n-3 fatty acids and tyrosine. During 2009-2011, new episodes of depression since baseline were identified using the lifetime version of the Composite International Diagnostic Interview. Relative risks were calculated using log-binomial regression and indirect effects estimated using the STATA binary_mediation command. Potential mediators were added to separate models, and mediation was quantified as the proportion of the total effect due to the mediator. The n-3 DHA mediated 25·3 % of the association between fish consumption and depression when fish consumption was analysed as a continuous variable and 16·6 % when dichotomised (reference group: <2 serves/week). Tyrosine did not mediate the association (<0·1 %). Components in fish other than n-3 fatty acids and tyrosine might be beneficial for women's mental health.

Diagnostic and treatment challenges in occlusal dysesthesia.

The aim of this chapter is to provide the dentist with an overview of potential diagnostic and treatment challenges posed by patients who present with occlusal dysesthesia or "Phantom Bite." Occlusal dysesthesia is seen as a form of somatoform disorder where dental treatments must be avoided and instead the focus should be on addressing the somatoform disorder through behavior change.

Quantification of changes in myofascial trigger point sensitivity with the pressure algometer following passive stretch.

In order to determine the relationship between trigger point sensitivity and the referred symptoms of myofascial pain, VAS ratings of referred pain intensity and pressure algometer measures of myofascial trigger point sensitivity were taken pre and post treatment of the muscle containing the trigger point with passive stretch. The results in 20 subjects, experiencing unilateral or bilateral myofascial head and neck pain, showed that myofascial trigger point sensitivity decreases in response to passive stretch as assessed by the pressure algometer, and that trigger point sensitivity and intensity of referred pain are related.

Reliability of the pressure algometer as a measure of myofascial trigger point sensitivity.

Three studies are presented demonstrating the reliability of the pressure algometer as an index of myofascial trigger point sensitivity. The first study showed high reliability between and within experimenters when measuring marked trigger point locations. In study 2, significant between experimenter reliability in locating and measuring the same unmarked trigger point locations was shown, while study 3 supported the idea that trigger points are discrete points of focal tenderness within the muscle. The ability to quantify and reliably measure trigger point sensitivity opens the door to a range of clinical and research possibilities for myofascial and related musculoskeletal pain problems.

Memory for pain: relation between past and present pain intensity.

Memory for the intensity of past physical pain depends critically on the intensity of present pain. When their present pain intensity was high, patients with chronic headaches of myofascial origin rated their maximum, usual, and minimum levels of prior pain as being more severe than their hourly pain diaries indicated. When their present pain intensity was low, the same patients remembered all 3 levels of prior pain as being less severe than they actually had been. The results show that pain produces systematic distortions of memory similar to those associated with alterations of affect or mood, and suggest a resolution to a conspicuous conflict in the current pain literature.

Effects of transcutaneous electrical nerve stimulation on myofascial pain and trigger point sensitivity.

The effects of transcutaneous electrical nerve stimulation (TENS) on myofascial pain and trigger point sensitivity were assessed. Four modes of TENS and a no-stimulation control were compared in a double-blind design. Stimulation, carried out for 10 min on 60 subjects (12/group), showed significant pain reductions with 100 Hz, 250 msec stimulation followed by 100 Hz, 50 msec and then pain suppressor TENS. No pain reductions were found in the 2 Hz, 250 msec TENS or the control. No significant alteration in myofascial trigger point sensitivity, assessed with the pressure algometer, was found between the groups. The results suggest that high frequency, high intensity TENS is effective in reducing myofascial pain, and that these pain reductions do not reflect changes in local trigger point sensitivity.

The effects of transcutaneous electrical nerve stimulation on experimental pain and sympathetic nervous system response.

OBJECTIVE: Transcutaneous electrical nerve stimulation (TENS) is a technique widely used in clinical practice to control pain, although its clinical efficacy remains controversial. Though many mechanisms have been proposed for its analgesic effects, there is a conspicuous lack of experimentally controlled research investigating whether TENS analgesia is related to its effects on the sympathetic nervous system (SNS). METHODS: Using an established psychophysiological paradigm, the present study investigated the effects of high-frequency/low-intensity TENS, low-frequency/high-intensity TENS, and sham TENS on the perception of experimental pain and SNS function in healthy volunteers. Measures of heart rate, digital pulse volume, and skin conductance were recorded during a 20-minute TENS stimulation period and in anticipation of a series of painful electric shocks prior to and following TENS stimulation. Healthy volunteers rated the intensity of the shocks using a 0-10-point verbal pain rating scale. RESULTS: The three TENS conditions failed to differentially effect SNS responses during either the 20-minute TENS treatment period or the shock anticipation periods, and TENS did not affect ratings of pain intensity to the shock stimuli. CONCLUSIONS: While these results may not generalize to acute or chronic pain patients, within the limitations of the present experimental paradigm, no support was found for TENS affecting either SNS function or acute experimental pain perception.

Multidimensional subgroups in migraine: differential treatment outcome to a pain medicine program.

OBJECTIVE: The present study compared two different approaches for deriving patient profiles on their ability to predict treatment outcome to a pain medicine program for migraine headache. DESIGN/METHODS: Using visual analog scale measures of pain intensity and functional limitations and the Beck Depression Inventory (BDI), as a measure of depression, 235 migraine patients were classified into statistical clusters. The same patients were also classified using the Multidimensional Pain Inventory (MPI) algorithm into three subgroups: Adaptive copers (AC), characterized by lower reported levels of pain intensity, life interference, and distress, as well as higher levels of perceived life control; interpersonally distressed (ID), characterized by more intermediate levels of pain, distress, and interference, with a predominant perception of inadequate support and punishing responses from significant others; and dysfunctional (Dys), characterized by high levels of pain severity, life interference, and distress and low levels of perceived life control and activity. RESULTS: The results of the K-cluster analysis yielded a three-cluster solution: The low impact cluster, was characterized by low pain, low functional limitations and low depression and showed significant reductions in pre-to-posttreatment pain; the moderate impact cluster displayed higher levels of pain and functional limitations and low depression and showed only slight pre-to-posttreatment pain reduction; and the high impact cluster displayed the highest levels of pain, functional limitations, and depression and showed significant increases in pre-to-posttreatment pain. Unlike the K-clustered groups, MPI subgroups failed to differentially predict treatment outcome. When the K-clustered groups were crosstabulated with the MPI subgroups, the predictive validity of the MPI subgroups was enhanced. CONCLUSION: This study questions the validity of the MPI subgroup classification algorithm. The results indicate that the K-clustering approach is more useful than the MPI in deriving meaningful patient clusters that differentially predict treatment outcome in a migraine population.