Table 1.

Factor pattern matrix for exploratory factor analysis with promax rotation of the DePaul Symptom Questionnaire

Scale-Item	Factor
	1 Neuroendocrine, Autonomic, and Immune Dysfunction	2 Neurological/Cognitive Dysfunction	3 Post-Exertional Malaise
58. Feeling hot or cold for no reason	.82
57. Feeling chills or shivers	.80		−.31
59. Feeling like you have a high temp.	.72
30. Abdomen/stomach pain	.63
63. Tender/sore lymph nodes	.61
50. Dizziness or fainting	.61
56. Cold limbs	.58
46. Irritable bowel problems	.57
55. Night sweats	.56
47. Nausea	.56
48. Feeling unsteady on your feet	.54
66. Chemical sensitivities	.54
62. Sore throat	.53
31. Headaches	.53
60. Feeling like you have a low temp.	.51
32. Muscle twitches	.50
25. Pain or aching in your muscles	.48		.33
64. Fever	.48
26. Multijoint pain	.48
45. Bladder problems	.47
29. Bloating	.44
65. Flu-like symptoms	.43		.30
24. Sleep all day/stay awake all night	.41
34. Sensitivity to noise	.40
35. Sensitivity to bright lights	.40
53. No appetite	.40
28. Chest pain	.39
49. Shortness of breath	.34
51. Irregular heart beats	.34
52. Losing/gaining weight w/o trying	.33
23. Waking up early in the morning	.33
39. Difficulty understanding things		.90
37. Difficulty paying attention		.89
43. Slowness of thought		.82
44. Absent-mindedness /forgetfulness		.78
41. Unable to focus vision/attention		.77
38. Difficulty expressing thoughts		.75
40. Only able to focus on one thing		.71
42. Loss of depth perception		.43
13. Fatigue/extreme tiredness			.82
15. Next day soreness or fatigue after non-strenuous activities			.81
18. Physically drained or sick after mild activity			.81
14. Dead, heavy feeling after starting to exercise			.72
33. Muscle weakness			.50
16. Mentally tired after the slightest effort		.46	.50
19. Feeling unrefreshed after waking			.50
Eigenvalue	14.4	2.7	2.3
Percentage variance explained	31.3%	5.8%	4.9%