In comparisons with controls, expressive writing produced significant benefits for individuals with a variety of medical problems (Box 3). Study participants with asthma or rheumatoid arthritis showed improvements in lung function and physician-rated disease severity respectively, following a laboratory-based writing progamme (Smyth et al, 1999), although people with rheumatoid arthritis using a home-based videotaped programme showed no benefit (Broderick et al, 2004). Some studies found that patients with cancer reported benefits such as better physical health, reduced pain and reduced need to use healthcare services (Rosenberg et al, 2002; Stanton & Danoff-Burg, 2002), although others failed to find any benefits (Walker et al, 1999; de Moor et al, 2002). Patients with HIV infection showed improved immune response similar to that seen in mono-therapy with anti-HIV drugs (Petrie et al, 2004) and individuals with cystic fibrosis showed a significant reduction in hospital-days over a 3-month period (Taylor et al, 2003). Women with chronic pelvic pain reported reductions in pain intensity ratings (Norman et al, 2004) and poor sleepers reported shorter sleep-onset latency (Harvey & Farrell, 2003). Benefits have also been found for post-operative course after papilloma resection (Solano et al, 2003) and for primary care patients (Klapow et al, 2001; Gidron et al, 2002).
Medical conditions that might benefit from expressive writing programmes
• Lung functioning in asthma
• Disease severity in rheumatoid arthritis
• Pain and physical health in cancer
• Immune response in HIV infection
• Hospitalisations for cystic fibrosis
• Pain intensity in women with chronic pelvic pain
• Sleep-onset latency in poor sleepers
• Post-operative course
Other studies have investigated expressive writing in preselected groups of trauma survivors and individuals with specific psychological difficulties, with mixed results. Students with a trauma history have shown improvements in physical health (Greenberg et al, 1996; Sloan & Marx, 2004a ), post-traumatic stress disorder (PTSD) symptomatology and other aspects of psychological health (Schoutrop et al, 1997, 2002; Sloan & Marx, 2004a ), although not all studies find benefits (Deters & Range, 2003).
Limited benefits were obtained for male psychiatric prison inmates (Richards et al, 2000), victims of natural disaster (Smyth et al, 2002) and individuals who had experienced a recent relationship breakup (Lepore & Greenberg, 2002).
Expressive writing was beneficial, but not significantly more so than control writing, for females writing about body image (Earnhardt et al, 2002), children of alcoholics (Gallant & Lafreniere, 2003), caregivers of children with chronic illness (Schwartz & Drotar, 2004), students screened for suicidality (Kovac & Range, 2002) and individuals who had experienced a bereavement (Range et al, 2000; O'Connor et al, 2003).
Compared with controls, expressive writing was detrimental for adult survivors of childhood abuse (Batten et al, 2002) and for a small sample of eight Vietnam veterans with PTSD (Gidron et al, 1996).
Our review of the literature shows that psychological health benefits tend to be more often found when participants’ traumas and/or symptoms are clinically more severe, although results are inconsistent. One explanation for this inconsistency may be that many of the studies with null findings instructed participants to write about the specific traumatic event they were selected for, rather than using the standard instructions (Box 1), which allow them to write about events of their choosing. In studies where expressive writing was beneficial, many participants wrote about topics other than their particular physical illness or psychological problem, but still showed improvements in that area (Smyth & Pennebaker, 1999).
In addition to studying specific health populations, researchers have explored various individual difference indices to identify those subgroups for whom expressive writing is most beneficial. Results have been inconsistent. Variables generally found to be unrelated to outcome include age, trauma severity, baseline physical and psychological health levels, negative affectivity and measures of inhibition and prior disclosure.
Smyth's (1998) meta-analysis found that the effects were greater for males than for females. Expressive writing is more beneficial for those high in alexithymia (Páez et al, 1999; Baikie, 2003; Solano et al, 2003) and high in splitting (Baikie, 2003), characteristics often seen in patients with psychosomatic disorders and borderline personality disorder respectively, suggesting potential for the use of expressive writing in these populations.