In their well designed two-phase cohort study, Ismail et al. (Reference Ismail, Kent, Sherwood, Hull, Seed, David and Wessely2008) found that a substantial number of UK veterans of the Gulf War of 1990–1991 who report (medically unexplained) physical disabilities meet the criteria for chronic fatigue syndrome (CFS). There appears to be a considerable overlap between CFS and the so-called Gulf War syndrome as this study and others reviewed by Ismail and colleagues show. This does not seem to be limited to veterans of the Gulf War. We found that 17% of Dutch (ex)-serviceman who were deployed in the 1992–1993 UNTAC peace operation in Cambodia were also severely fatigued. They also reported a high frequency of other CFS symptoms, like unrefreshing sleep, joint pain, and difficulty concentrating (De Vries et al. Reference Vries, Soetekouw, Bleijenberg and Van der Meer2000).

CFS can effectively be treated by cognitive behaviour therapy (CBT) that is aimed at the behaviour and cognitions that perpetuate the fatigue and disabilities (Price et al. Reference Price, Mitchell, Tidy and Hunot2008). Ismail and colleagues suggest that the same model could also be used for those Gulf War veterans who have CFS-like symptoms. Indeed, the study of Donta et al. (Reference Donta, Clauw, Engel, Guarino, Peduzzi, Williams, Skinner, Barkhuizen, Taylor, Kazis, Sogg, Hunt, Dougherty, Richardson, Kunkel, Rodriguez, Alicea, Chiliade, Ryan, Gray, Lutwick, Norwood, Smith, Everson, Blackburn, Martin, Griffiss, Cooper, Renner, Schmitt, McMurtry, Thakore, Mori, Kerns, Park, Pullman-Mooar, Bernstein, Hershberger, Salisbury and Feussner2003) showed that CBT aimed at a gradual increase of activity and improvement of coping and problem-solving skills was effective in treating symptomatic Gulf War veterans. However, this study found only moderate positive effects on physical functioning compared to the effects of CBT for CFS patients. We suggest that this difference may be explained by the fact that for the treatment of CFS, a specific model of maintaining factors with specific interventions is used. In the trial of Donta et al. (Reference Donta, Clauw, Engel, Guarino, Peduzzi, Williams, Skinner, Barkhuizen, Taylor, Kazis, Sogg, Hunt, Dougherty, Richardson, Kunkel, Rodriguez, Alicea, Chiliade, Ryan, Gray, Lutwick, Norwood, Smith, Everson, Blackburn, Martin, Griffiss, Cooper, Renner, Schmitt, McMurtry, Thakore, Mori, Kerns, Park, Pullman-Mooar, Bernstein, Hershberger, Salisbury and Feussner2003), a rather non-specific form of CBT was offered to symptomatic Gulf War veterans.

That not all (medically unexplained) chronic fatigue is maintained by the same behaviour and cognitions is not new. Gielissen et al. (Reference Gielissen, Verhagen, Witjes and Bleijenberg2006) developed a model for chronic fatigue in cancer survivors that was different from the model of perpetuating factors used for CFS patients. Perpetuating factors that were specific for cancer survivors – like fear of disease recurrence or coping with the experience of cancer – were included in this model. CBT based on this specific model of post-cancer fatigue proved to be highly effective in treating chronic fatigue in cancer survivors.

It is likely that the CFS-like symptoms of veterans with Gulf War syndrome could be more effectively treated if CBT also addresses the perpetuating factors that are specific for the ‘post-deployment syndrome’ (De Vries, Reference Vries2002). Examples of these specific factors are the subjective experience of the mission, the attribution of somatic symptoms (like malaria medication and vaccinations in the case of Dutch Cambodia Veterans), changes in career perspective, and the perceived lack of attention, recognition, and respect. CBT aimed at these factors combined with interventions directed at the more non-specific perpetuating behaviours and cognitions (e.g. low physical activity, disturbed sleep–wake cycle, low self-efficacy, focusing on bodily symptoms) is probably more effective in reducing ‘CFS-like’ symptoms in veterans with a post-deployment syndrome.