The Neuropsychiatric and Neuropsychological Features of Chronic Fatigue Syndrome: Revisiting the Enigma

  • Yvonne Christley
  • Tim Duffy
  • Ian Paul Everall
  • Colin R. Martin
Complex Medical-Psychiatric Issues (MB Riba, Section Editor)
Part of the following topical collections:
  1. Topical Collection on Complex Medical-Psychiatric Issues

Abstract

The aim of this article is to provide a comprehensive and updated review of the key neuropsychiatric and neuropsychological complaints associated with chronic fatigue syndrome (CFS). Neuropsychiatric and neuropsychological difficulties are common in CFS and are linked primarily to disorders of mood, affect and behaviour. The neuropsychiatric complaint most frequently encountered amongst CFS patients is depression and in particular major depressive disorder (MDD). Despite decades of research, the precise aetiological relationship between CFS and MDD remains poorly understood. This has resulted in the development of a number of interesting and polarised hypotheses regarding the aetiological nature of CFS. Recent scientific advances have however begun to unravel a number of interesting inflammatory and immunological explanations that suggest CFS and MDD are distinct yet interrelated conditions. The possibility that the overlap between CFS and MDD might be explained in terms of shared oxidative and nitrosative (IO&NS) pathways is an area of intense research interest and is reviewed in detail in this article. The overlap between CFS and MDD is further differentiated by variations in HPA axis activity between the two disorders. Important immunological differences between MDD and CFS are also reviewed with particular emphasis on antiviral RNase L pathways in CFS. In addition to the presence of neuropsychiatric complaints, CFS is also associated with neuropsychological symptoms such as impaired attention, memory and reaction time. The key neuropsychological problems reported by CFS patients are also included in the review in an effort to understand the significance of cognitive impairment in CFS.

Keywords

Chronic fatigue syndrome CFS Depression Generalised anxiety disorder Neuropsychiatric Neuropsychological Major depressive disorder MDD Somatoform disorder Personality disorder Attention Memory Reaction time 

Notes

Disclosure

Y. Christley declares that she has no conflict of interest.

T. Duffy declares that he has no conflict of interest.

I. P. Everall has received compensation for lectures including service on speakers’ bureaus from Abbot and AstraZeneca.

C. R. Martin declares that he has no conflict of interest.

References

Papers of particular interest, published recently, have been highlighted as: •• Of major importance

  1. 1.
    •• Christley Y, Duffy T, Martin CR. A review of the definitional criteria for chronic fatigue syndrome. J Eval Clin Pract. 2012;18:25–31. This important paper highlights longstanding inconsistencies and irregularities in definitional criteria regarding CFS and the implications that these enduring inconsistencies may have on developing convincing aetiological accounts. PubMedCrossRefGoogle Scholar
  2. 2.
    Jason LA, Taylor R, Wagner L, Holden J, Ferrari JR, Plioplys AV, et al. Estimating rates of chronic fatigue syndrome from a community-based sample: a pilot study. Am J Community Psychol. 1995;23:557–68.PubMedCrossRefGoogle Scholar
  3. 3.
    Jason LA, Porter N, Hunnell J, Brown A, Rademaker A, Richman JA. A natural history study of chronic fatigue syndrome. Rehabil Psychol. 2011;56:32–42.PubMedCrossRefGoogle Scholar
  4. 4.
    Buchwald D, Pearlman T, Umali J, Schmaling K, Katon W. Functional status in patients with chronic fatigue syndrome, other fatiguing illnesses, and healthy individuals. Am J Med. 1996;101:364–70.PubMedCrossRefGoogle Scholar
  5. 5.
    Bombardier CH, Buchwald D. Chronic fatigue, chronic fatigue syndrome, and fibromyalgia. Disability and health-care use. Med Care. 1996;34:924–30.PubMedCrossRefGoogle Scholar
  6. 6.
    McCrone P, Darbishire L, Ridsdale L, Seed P. The economic cost of chronic fatigue and chronic fatigue syndrome in UK primary care. Psychol Med. 2003;33:253–61.PubMedCrossRefGoogle Scholar
  7. 7.
    Ross SD, Estok RP, Frame D, Stone LR, Ludensky V, Levine CB. Disability and chronic fatigue syndrome: a focus on function. Arch Intern Med. 2004;164:1098–107.PubMedCrossRefGoogle Scholar
  8. 8.
    Manu P, Affleck G, Tennen H, Morse PA, Escobar JI. Hypochondriasis influences quality-of-life outcomes in patients with chronic fatigue. Psychother Psychosom. 1996;65:76–81.PubMedCrossRefGoogle Scholar
  9. 9.
    Fuller-Thomson E, Nimigon J. Factors associated with depression among individuals with chronic fatigue syndrome: findings from a nationally representative survey. Fam Pract. 2008;25:414–22.PubMedCrossRefGoogle Scholar
  10. 10.
    Iwase M, Okajima R, Takahashi T, Mogami N, Kusaka H, Takeda M, et al. Psychiatric treatment and assessment of chronic fatigue syndrome in Japan. In: Watanabe Y, Evengård B, Natelson BH, Jason LA, Kuratsune H, editors. Fatigue science for human health. Springer: London; 2008. p. 103–19.Google Scholar
  11. 11.
    Wessely S, Chalder T, Hirsch S, Wallace P, Wright D. Psychological symptoms, somatic symptoms, and psychiatric disorder in chronic fatigue and chronic fatigue syndrome: a prospective study in the primary care setting. Am J Psychiatr. 1996;153:1050–9.PubMedGoogle Scholar
  12. 12.
    Manu P, Lane TJ, Matthews DA. Chronic fatigue and chronic fatigue syndrome: clinical epidemiology and aetiological classification. CIBA Found Symp. 1993;173:23–31.PubMedGoogle Scholar
  13. 13.
    Offenbaecher M, Glatzeder K, Ackenheil M. Self-reported depression, familial history of depression and fibromyalgia (FM), and psychological distress in patients with FM. Z Rheumatol. 1998;57 Suppl 2:94–6.PubMedCrossRefGoogle Scholar
  14. 14.
    Buchwald D, Pearlman T, Kith P, Katon W, Schmaling K. Screening for psychiatric disorders in chronic fatigue and chronic fatigue syndrome. J Psychosom Res. 1997;42:87–94.PubMedCrossRefGoogle Scholar
  15. 15.
    Van Houdenhove B, Kempke S, Luyten P. Psychiatric aspects of chronic fatigue syndrome and fibromyalgia. Curr Psychiatr Rep. 2010;12:208–14.CrossRefGoogle Scholar
  16. 16.
    Leonard B, Maes M. Mechanistic explanations how cell-mediated immune activation, inflammation and oxidative and nitrosative stress pathways and their sequels and concomitants play a role in the pathophysiology of unipolar depression. Neurosci Biobehav Rev. 2012;36:764–85.PubMedCrossRefGoogle Scholar
  17. 17.
    Axe EK, Satz P, Rasgon NL, Fawzy FI. Major depressive disorder in chronic fatigue syndrome: a CDC Surveillance Study. J Chron Fatigue Syndr. 2004;12:7–23.CrossRefGoogle Scholar
  18. 18.
    Roy-Byrne P, Afari N, Ashton S, Fischer M, Goldberg J, Buchwald D. Chronic fatigue and anxiety/depression: a twin study. Br J Psychiatry. 2002;180:29–34.PubMedCrossRefGoogle Scholar
  19. 19.
    Wessely S, Chalder T, Hirsch S, Wallace P, Wright D. The prevalence and morbidity of chronic fatigue and chronic fatigue syndrome: A prospective primary care study. Am J Public Health. 1997;87:1449–55.PubMedCrossRefGoogle Scholar
  20. 20.
    Nater UM, Jones JF, Lin JM, Maloney E, Reeves WC, Heim C. Personality features and personality disorders in chronic fatigue syndrome: a population-based study. Psychother Psychosom. 2010;79:312–8.PubMedCrossRefGoogle Scholar
  21. 21.
    Taylor RR, Jason LA, Jahn SC. Chronic fatigue and sociodemographic characteristics as predictors of psychiatric disorders in a community-based sample. Psychosom Med. 2003;65:896–901.PubMedCrossRefGoogle Scholar
  22. 22.
    Murrough JW, Mao X, Collins KA, Kelly C, Andrade G, Nestadt P, et al. Increased ventricular lactate in chronic fatigue syndrome measured by 1H MRS imaging at 3.0 T. II: comparison with major depressive disorder. NMR In Biomed. 2010;23:643–50.CrossRefGoogle Scholar
  23. 23.
    Zimmermann TT, Sattel HH. Medically unexplained physical symptoms, anxiety, and depression: a meta-analytic review. Psychosom Med. 2003;65:528.PubMedCrossRefGoogle Scholar
  24. 24.
    Duffy FH, McAnulty GB, McCreary MC, Cuchural GJ, Komaroff AL. EEG spectral coherence data distinguish chronic fatigue syndrome patients from healthy controls and depressed patients-A case control study. Bmc Neurol. 2011; 11.Google Scholar
  25. 25.
    Johnson SK, DeLuca J, Natelson BH. Depression in fatiguing illness: comparing patients with chronic fatigue syndrome, multiple sclerosis and depression. J Affect Disord. 1996;39:21–30.PubMedCrossRefGoogle Scholar
  26. 26.
    Powell R, Dolan R, Wessely S. Attributions and self-esteem in depression and chronic fatigue syndromes. J Psychosom Res. 1990;34:665–73.PubMedCrossRefGoogle Scholar
  27. 27.
    Hawk C, Jason LA, Torres-Harding S. Differential diagnosis of chronic fatigue syndrome and major depressive disorder. Int J Behav Med. 2006;13:244–51.PubMedCrossRefGoogle Scholar
  28. 28.
    Jason LA, Richman JA, Friedberg F, Wagner L, Taylor R, Jordan KM. Politics, science, and the emergence of a new disease. The case of chronic fatigue syndrome. Am Psychol. 1997;52:973–83.PubMedCrossRefGoogle Scholar
  29. 29.
    Silver A, Haeney M, Vijayadurai P, Wilks D, Pattrick M, Main CJ. The role of fear of physical movement and activity in chronic fatigue syndrome. J Psychosom Res. 2002;52:485–93.PubMedCrossRefGoogle Scholar
  30. 30.
    Maes M, Twisk FNM. Treatment of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a multisystem disease, should target the pathophysiological aberrations (inflammatory and oxidative and nitrosative stress pathways), not the psychosocial “barriers” for a new equilibrium. Patient Educ Couns. 2010;80:148–9.PubMedCrossRefGoogle Scholar
  31. 31.
    Maes M, Mihaylova I, Leunis JC. Increased serum IgM antibodies directed against phosphatidyl inositol (Pi) in chronic fatigue syndrome (CFS) and major depression: evidence that an IgM-mediated immune response against Pi is one factor underpinning the comorbidity between both CFS and depression. Neuro Endocrinol Lett. 2007;28:861–7.PubMedGoogle Scholar
  32. 32.
    Roberts AD, Papadopoulos AS, Wessely S, Chalder T, Cleare AJ. Salivary cortisol output before and after cognitive behavioural therapy for chronic fatigue syndrome. J Affect Disord. 2009;115:280–6.PubMedCrossRefGoogle Scholar
  33. 33.
    Cleare A. The neuroendocrinology of chronic fatigue syndrome. Endocr Rev. 2003;24:236–52.PubMedGoogle Scholar
  34. 34.
    Maes M, Twisk FNM. Chronic fatigue syndrome: Harvey and Wessely’s (bio)psychosocial model versus a bio(psychosocial) model based on inflammatory and oxidative and nitrosative stress pathways. Bmc Medicine, 2010; 8.Google Scholar
  35. 35.
    Hinkelmann K, Moritz S, Botzenhardt J, Muhtz C, Wiedemann K, Kellner M, Otte C. Changes in cortisol secretion during antidepressive treatment and cognitive improvement in patients with major depression: A longitudinal study. Psychoneuroendocrinology, 2011.Google Scholar
  36. 36.
    Hinkelmann K, Moritz S, Botzenhardt J, Riedesel K, Wiedemann K, Kellner M, et al. Cognitive impairment in major depression: association with salivary cortisol. Biol Psychiatry. 2009;66:879–85.PubMedCrossRefGoogle Scholar
  37. 37.
    Gomez RG, Posener JA, Keller J, DeBattista C, Solvason B, Schatzberg AF. Effects of major depression diagnosis and cortisol levels on indices of neurocognitive function. Psychoneuroendocrinology. 2009;34:1012–8.PubMedCrossRefGoogle Scholar
  38. 38.
    Jerjes W, Taylor N, Wood P, Cleare A. Enhanced feedback sensitivity to prednisolone in chronic fatigue syndrome. Psychoneuroendocrinology. 2007;32:192–8.PubMedCrossRefGoogle Scholar
  39. 39.
    Nater UM, Youngblood LS, Jones JF, Unger ER, Miller AH, Reeves WC, et al. Alterations in diurnal salivary cortisol rhythm in a population-based sample of cases with chronic fatigue syndrome. Psychosom Med. 2008;70:298–305.PubMedCrossRefGoogle Scholar
  40. 40.
    Nater UM, Maloney E, Boneva RS, Gurbaxani BM, Lin JM, Jones JF, et al. Attenuated morning salivary cortisol concentrations in a population-based study of persons with chronic fatigue syndrome and well controls. J Clin Endocrinol Metab. 2008;93:703–9.PubMedCrossRefGoogle Scholar
  41. 41.
    Turan T, Izgi HB, Ozsoy S, Tanrıverdi F, Basturk M, Asdemir A, et al. The effects of galantamine hydrobromide treatment on dehydroepiandrosterone sulfate and cortisol levels in patients with chronic fatigue syndrome. Psychiatr Investig. 2009;6:204–10.CrossRefGoogle Scholar
  42. 42.
    Parker LN, Levin ER, Lifrak ET. Evidence for adrenocortical adaptation to severe illness. J Clin Endocrinol Metab. 1985;60:947–52.PubMedCrossRefGoogle Scholar
  43. 43.
    Scott LV, Svec F, Dinan T. A preliminary study of dehydroepiandrosterone response to low-dose ACTH in chronic fatigue syndrome and in healthy subjects. Psychiatr Res. 2000;97:21–8.CrossRefGoogle Scholar
  44. 44.
    Himmel PB, Seligman TM. A pilot study employing Dehydroepiandrosterone (DHEA) in the treatment of chronic fatigue syndrome. J Clin Rheumatol. 1999;5:56–9.PubMedCrossRefGoogle Scholar
  45. 45.
    Liang SL, Quirk D, Zhou A. RNase L: its biological roles and regulation. IUBMB Life. 2006;58:508–14.PubMedCrossRefGoogle Scholar
  46. 46.
    Nijs J, De Meirleir K. Impairments of the 2-5A synthetase/RNase L pathway in chronic fatigue syndrome. In Vivo. 2005;19:1013–21.PubMedGoogle Scholar
  47. 47.
    Suhadolnik RJ, Peterson DL, Reichenbach NL, Roen G, Metzger M, McCahan J, et al. Clinical and biochemical characteristics differentiating chronic fatigue syndrome from major depression and healthy control populations: relation to dysfunction in the RNase L pathway. J Chron Fatigue Syndr. 2004;12:5–35.CrossRefGoogle Scholar
  48. 48.
    De Meirleir K, Bisbal C, Campine I, De Becker P, Salehzada T, Demettre E, et al. A 37 kDa 2-5A binding protein as a potential biochemical marker for chronic fatigue syndrome. Am J Med. 2000;108:99–105.PubMedCrossRefGoogle Scholar
  49. 49.
    Hickie I, Lloyd A, Wakefield D, Parker G. The psychiatric status of patients with the chronic fatigue syndrome. Br J Psychiatry. 1990;156:534–40.PubMedCrossRefGoogle Scholar
  50. 50.
    Pepper CM, Krupp LB, Friedberg F, Doscher C, Coyle PK. A comparison of neuropsychiatric characteristics in chronic fatigue syndrome, multiple sclerosis, and major depression. J Neuropsychiatr Clin Neurosci. 1993;5:200–5.Google Scholar
  51. 51.
    Moss-Morris R, Petrie KJ. Discriminating between chronic fatigue syndrome and depression: a cognitive analysis. Psychol Med. 2001;31:469–79.PubMedCrossRefGoogle Scholar
  52. 52.
    Somers JM, Goldner EM, Waraich P, Hsu L. Prevalence and incidence studies of anxiety disorders: a systematic review of the literature. Can J Psychiatr Rev Can Psychiatr. 2006;51:100–13.Google Scholar
  53. 53.
    Stein DJ, Ruscio AM, Lee S, Petukhova M, Alonso J, Andrade LH, et al. Subtyping social anxiety disorder in developed and developing countries. Depress Anxiety. 2010;27:390–403.PubMedCrossRefGoogle Scholar
  54. 54.
    Kessler RC, Keller MB, Wittchen HU. The epidemiology of generalized anxiety disorder. Psychiatr Clin North Am. 2001;24:19–39.PubMedCrossRefGoogle Scholar
  55. 55.
    Fischler B, Dendale P, Michiels V, Cluydts R, Kaufman L, De Meirleir K. Physical fatigability and exercise capacity in chronic fatigue syndrome: association with disability, somatization and psychopathology. J Psychosom Res. 1997;42:369–78.PubMedCrossRefGoogle Scholar
  56. 56.
    Nutt DJ. Neurobiological mechanisms in generalized anxiety disorder. J Clin Psychiatr. 2001;62 Suppl 11:22–7. discussion 28.Google Scholar
  57. 57.
    Lipowski ZJ. Somatization: the concept and its clinical application. Am J Psychiatr. 1988;145:1358–68.PubMedGoogle Scholar
  58. 58.
    Kirmayer LJ, Robbins JM, Paris J. Somatoform disorders: personality and the social matrix of somatic distress. J Abnorm Psychol. 1994;103:125–36.PubMedCrossRefGoogle Scholar
  59. 59.
    Abbey SE. Somatization, illness attribution and the sociocultural psychiatry of chronic fatigue syndrome. CIBA Found Symp. 1993;173:238–52. discussion 252–61.PubMedGoogle Scholar
  60. 60.
    Johnson SK, DeLuca J, Natelson BH. Assessing somatization disorder in the chronic fatigue syndrome. Psychosom Med. 1996;58:50–7.PubMedGoogle Scholar
  61. 61.
    Manu P, Lane TJ, Matthews DA, Escobar JI. Screening for somatization disorder in patients with chronic fatigue. Gen Hosp Psychiatr. 1989;11:294–7.CrossRefGoogle Scholar
  62. 62.
    Demitrack MA. Neuroendocrine research strategies in chronic fatigue syndrome. In: Goodnick PJ, Klimas NG, editors. Chronic fatigue and related immune deficiency syndromes. Washington: American Psychiatric Press; 1993. p. 45–66.Google Scholar
  63. 63.
    Katon WJ, Walker EA. The relationship of chronic fatigue to psychiatric illness in community, primary care and tertiary care samples. CIBA Found Symp. 1993;173:193–204. discussion 204–11.PubMedGoogle Scholar
  64. 64.
    Katon W, Russo J. Chronic fatigue syndrome criteria. A critique of the requirement for multiple physical complaints. Arch Intern Med. 1992;152:1604–9.PubMedCrossRefGoogle Scholar
  65. 65.
    Johnson SK, DeLuca J, Natelson BH. Personality dimensions in the chronic fatigue syndrome: a comparison with multiple sclerosis and depression. J Psychiatr Res. 1996;30:9–20.PubMedCrossRefGoogle Scholar
  66. 66.
    Ciccone DS, Busichio K, Vickroy M, Natelson BH. Psychiatric morbidity in the chronic fatigue syndrome: Are patients with personality disorder more physically impaired? J Psychosom Res. 2003;54:445–52.PubMedCrossRefGoogle Scholar
  67. 67.
    Moran P, Coffey C, Mann A, Carlin JB, Patton GC. Dimensional characteristics of DSM-IV personality disorders in a large epidemiological sample. Acta Psychiatr Scand. 2006;113:233–6.PubMedCrossRefGoogle Scholar
  68. 68.
    Glass JM. Cognitive dysfunction in fibromyalgia and chronic fatigue syndrome: new trends and future directions. Curr Rheumatol Rep. 2006;8:425–9.PubMedCrossRefGoogle Scholar
  69. 69.
    Michiels V, Cluydts R. Neuropsychological functioning in chronic fatigue syndrome: a review. Acta Psychiatr Scand. 2001;103:84–93.PubMedCrossRefGoogle Scholar
  70. 70.
    Caseras X, Mataix-Cols D, Giampietro V, Rimes KA, Brammer M, Zelaya F, et al. Probing the working memory system in chronic fatigue syndrome: a functional magnetic resonance imaging study using the n-back task. Psychosom Med. 2006;68:947–55.PubMedCrossRefGoogle Scholar
  71. 71.
    Claypoole KH, Noonan C, Mahurin RK, Goldberg J, Erickson T, Buchwald D. A twin study of cognitive function in chronic fatigue syndrome: The effects of sudden illness onset. Neuropsychology. 2007;21:507–13.PubMedCrossRefGoogle Scholar
  72. 72.
    Mahurin RK, Claypoole KH, Goldberg JH, Arguelles L, Ashton S, Buchwald D. Cognitive processing in monozygotic twins discordant for chronic fatigue syndrome. Neuropsychology. 2004;18:232–9.PubMedCrossRefGoogle Scholar
  73. 73.
    Deluca J, Christodoulou C, Diamond BJ, Rosenstein ED, Kramer N, Natelson BH. Working memory deficits in chronic fatigue syndrome: differentiating between speed and accuracy of information processing. J Int Neuropsychol Soc. 2004;10:101–9.PubMedCrossRefGoogle Scholar
  74. 74.
    Chiaravalloti ND, Christodoulou C, Demaree HA, DeLuca J. Differentiating simple versus complex processing speed: influence on new learning and memory performance. J Clin Exp Neuropsychol. 2003;25:489–501.PubMedCrossRefGoogle Scholar
  75. 75.
    Crowe SF, Casey A. A neuropsychological study of the chronic fatigue syndrome: support for a deficit in memory function independent of depression. Aust Psychol. 1999;34:70–5.CrossRefGoogle Scholar
  76. 76.
    Fiedler N, Kipen HM, DeLuca J, Kelly-McNeil K, Natelson B. A controlled comparison of multiple chemical sensitivities and chronic fatigue syndrome. Psychosom Med. 1996;58:38–49.PubMedGoogle Scholar
  77. 77.
    Tiersky LA, Johnson SK, Lange G, Natelson BH, DeLuca J. Neuropsychology of chronic fatigue syndrome: a critical review. J Clin Exp Neuropsychol. 1997;19:560–86.PubMedCrossRefGoogle Scholar
  78. 78.
    Cockshell S, Mathias J. Cognitive functioning in chronic fatigue syndrome: a meta-analysis. Psychol Med. 2010;40:1253–67.PubMedCrossRefGoogle Scholar
  79. 79.
    Majer M, Welberg LA, Capuron L, Miller AH, Pagnoni G, Reeves WC. Neuropsychological performance in persons with chronic fatigue syndrome: results from a population-based study. Psychosom Med. 2008;70:829–36.PubMedCrossRefGoogle Scholar
  80. 80.
    Tiersky LA, Matheis RJ, Deluca J, Lange G, Natelson BH. Functional status, neuropsychological functioning, and mood in chronic fatigue syndrome (CFS): relationship to psychiatric disorder. J Nerv Ment Dis. 2003;191:324–31.PubMedGoogle Scholar
  81. 81.
    •• Duffy FH, McAnulty GB, McCreary MC, Cuchural GJ, Komaroff AL. EEG spectral coherence data distinguish chronic fatigue syndrome patients from healthy controls and depressed patients—a case control study. BMC Neurol. 2011;11:82. This excellent paper highlights evidence of important and distinguising features of abnormal brain physiology suggesting temporal lobe involvement in CFS. PubMedCrossRefGoogle Scholar
  82. 82.
    Wearden A, Appleby L. Cognitive performance and complaints of cognitive impairment in chronic fatigue syndrome (CFS). Psychol Med. 1997;27:81–90.PubMedCrossRefGoogle Scholar
  83. 83.
    Lutgendorf SK, Antoni MH, Ironson G, Fletcher MA, Penedo F, Baum A, et al. Physical symptoms of chronic fatigue syndrome are exacerbated by the stress of Hurricane Andrew. Psychosom Med. 1995;57:310–23.PubMedGoogle Scholar
  84. 84.
    Daly E, Komaroff AL, Bloomingdale K, Wilson S, Albert MS. Neuropsychological function in patients with chronic fatigue syndrome, multiple sclerosis, and depression. Appl Neuropsychol. 2001;8:12–22.PubMedCrossRefGoogle Scholar
  85. 85.
    Capuron L, Welberg L, Heim C, Wagner D, Solomon L, Papanicolaou DA, et al. Cognitive dysfunction relates to subjective report of mental fatigue in patients with chronic fatigue syndrome. Neuropsychopharmacology. 2006;31:1777–84.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • Yvonne Christley
    • 1
  • Tim Duffy
    • 1
  • Ian Paul Everall
    • 2
  • Colin R. Martin
    • 1
    • 3
  1. 1.School of Health, Nursing and MidwiferyUniversity of the West of ScotlandAyrUK
  2. 2.Department of PsychiatryUniversity of MelbourneMelbourneAustralia
  3. 3.School of Health, Nursing and MidwiferyUniversity of the West of ScotlandBeech GroveUK

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