rate, and peak expiratory flow rate. Immune Disorders HIV-Positive Adults Immune disorders might be expected to benefit from massage therapy because of the decrease in cortisol levels noted in several previous studies. Elevated cortisol is known to dampen immune function. In a study we conducted on HIV-positive adults, natural killer (NK) cells and natural killer cell cytotoxicity (activity) increased following 20 days of massage therapy (Ironson et al., 1996). Twenty-nine gay men (20 HIV+, 9 HIV-) were massaged for one month and compared with a progressive muscle relaxation group. A subset of 11 of the HIVpositive men served as a within-subjects control group (one month with and one month without massages). Major immune findings included a significant increase in NK cell number, NK cell cytotoxicity, and subsets of CD8 cells. There were no changes in HIV disease progression markers (CD4, CD4/CD8 ratios), possibly because the HIV men were already severely immune compromised. A significant decrease was also noted in urinary cortisol, and nonsignificant trends suggested decreased catecholamines. Decreased anxiety was significantly correlated with increased NK cell number. Elevated stress hormones (catecholamines and cortisol) are noted to negatively affect immune function. The increase in cytotoxic capacity associated with massage therapy probably derives from the decrease in these stress hormones following massage therapy. Because NK cells are the front line of defense in the immune system, combating the growth and proliferation of viral cells, the HIV-positive patients who received the massage therapy might experience fewer opportunistic infections such as pneumonia and other viruses that often kill them. The increased NK cells also suggest that cancer patients may benefit from massage therapy inasmuch as NK cells are also noted to combat cancer cells. Breast Cancer Nineteen women (M age = 53 years) with Stage I or II breast cancer were assigned to a massage therapy or control group (Hernandez-Reif, Field, Ironson, et al., 1998). The massage therapy group received three 45-minute massages per week for five weeks. Lymphocyte markers (CD56 + cells, CD3 + cells, CDlla+ cells) and NK cell numbers were significantly increased for the women in the massage group by the end of the study. Immediately after their first and last massage, the massage therapy group reported less anxiety, anger, and pain, and improved mood. Longer term changes for the massage therapy group included improved body image awareness and physical well-being, and decreased depression. Summary These, then, are the functions that have improved following massage therapy. In addition to each clinical condition being marked by unique changes such as the increased peak air flow noted in the asthma study and the decreased glucose levels noted in the children with diabetes, there December 1998 • American Psychologist 1277 was also a set of common findings. Across studies, decreases were noted in anxiety, depression, stress hormones (cortisol), and catecholamines. Increased parasympathetic activity may be the underlying mechanism for these changes. The pressure stimulation associated with touch may increase vagal activity, which in turn lowers physiological arousal and stress hormones (cortisol levels). The pressure is critical because light stroking is generally aversive (much like a tickle stimulus), and the above effects have not been noted for light stroking. Decreased cortisol in turn leads to enhanced immune function. Parasympathetic activity is also associated with increased alertness and better performance on cognitive tasks (Porges, 1997). Given that most diseases are exacerbated by stress and that massage therapy alleviates stress, this alternative treatment may help reduce stress-related disease. Future directions for research may be discussed in the context of the most frequently raised questions about massage therapy. Those include the questions of whether massage therapy effects can be demonstrated in an equivalent way for healthy volunteer individuals in experimental conditions in contrast to the typical demonstration on individuals with medical conditions. Additionally, can the massage therapy effects occur using mechanical massage stimulation as opposed to human massage therapy? A third frequently raised question has to do with the underlying mechanism for the effects of massage therapy. Other occasionally raised questions are whether massage therapy has lasting effects, whether there are contraindications for massage therapy, and whether any particular massage therapy techniques are more effective than others. The literature has been equivocal about the question of massage therapy effects on healthy individuals. Most studies have focused on alleviating symptoms and combating disease, and literally no prevention studies appear in the literature. Probably the closest massage therapy literature that addresses the question is the literature focusing on sports and the effects of athletic massage. This, however, is a mixed-results literature. Typically the studies have focused on the effects of athletic massage on delayed onset muscle soreness and waste products. In such studies it is hypothesized that athletic massage administered after extensive exercise (typically two hours after the