little boy  
 
   

Summary of Research Examining the Prevalence of Full or Partial  Dissociative Amnesia for Traumatic Events

The most comprehensive review of the scientific literature on dissociative amnesia has been conducted by Brown, Scheflin and Hammond in their book, Memory, Trauma Treatment, and the Law . (New York: Norton, 1998). This book is viewed as setting the standard in the field after receiving the American Psychiatric Association's 1999 prestigious Manfred S. Guttmacher Award for best book in law and forensic psychiatry.

Brown, Scheflin and Hammond reviewed 43 studies relevant to the subject of traumatic memory and found that every study that examined the question of dissociative amnesia in traumatized populations demonstrated that a substantial minority partially or completely forget the traumatic event experienced, and later recover memories of the event.

Dissociative amnesia can occur after any type of traumatic event.

Table 1

Traumatic Amnesia Among Survivors of Physical Abuse, Rape, War, Accidents, and Disaster:

Percent of Sample*

Source

Sample Size

Amnesia

 

Sample

    None
F +P
Partial Full  

Physical Abuse

 

 

 

 

 

 

 

Elliott & Briere, 1995

485

75

25

15

10

general census

 

Elliott & Fox, 1994

484

73

27

10

17

undergraduates

 

Golding et al., 1996

613

 

21

 

 

undergraduates

 

Melchert, 1996

553

 

21

 

11

college students

 

Fish & Scott, 1999

423

 

21

 

10

counseling psychologists

 

Femina et al., 1990

69

26/8

 

 

 

9-year prospective

 

Robins, 1966

524/71

78

 

 

 

prospective study on delinquency

 

Widom & Shepard, 1996

110

 

40

 

 

prospective study

Rape

 

 

 

 

 

 

Elliott & Briere, 1995

485

77

23

10

13

general census

Combat

 

 

 

 

 

 

Sargant & Slater, 1941

1000

85.6

14.4

 

 

WWII consecutive cases

 

Elliott & Briere, 1995

485

61

39

23

16

combat

POW

 

 

 

 

 

 

Wagenaar & Groeneweg, 1990

78

gist

Injury; death threat

 

 

Camp Erika

Car Accident

 

 

 

 

 

 

Elliott & Briere, 1995

485

92

8

4

4

general census

Disaster

 

 

 

 

 

 

Dollinger, 1985

33

 

3

 

 

child lightening victims

 

McFarlane, 1988

469

100

57§

 

 

Australian bushfire

 

Wilkinson, 1983

102

27

 

 

Hyatt skywalk collapse

 

Eriksson & Lundin, 1996

53

 

29

 

 

m/s Estonia disaster

*  Adapted from Table 7.4 in Brown et al. (1998); F+P  = combined percentage of full and partial amnesia; denial; memory disturbance (intrusive memory or amnesia);  § failed to report injury at 11 months

Research shows that a period of either partial or full amnesia is reported by between 30 and 90% of adult victims of childhood sexual abuse.

Table 2

Amnesia for Childhood Sexual Abuse: Percent of Sample*

Source

N

F

P

F+P

No A

IC

Rx

c/nc

r/nr

Sample

Clinical Studies

 

 

 

 

 

 

 

 

 

 

 

Herman & Schatzow, 1987

53

28

36

64

36

74

100

c

nr

Outpatient Rx

 

Draijer, 1990

1,054

 

 

57

 

 

 

 

 

National survey

 

Ensink, 1992

100

29

28

57

43

 

100

c

nr

Incest & rx groups (high DID)

 

Albach et al., in press

97e

65c

 

 

35

1

65

99

 

100

c

nr

Women with hx of CSA

Normal controls

 

Cameron, 1994

60

42

23

65

35

 

100

c

nr

Women in rx with hx of CSA

 

Loftus et al., 1994

105

19

12

31

69

 

 

c

nr

Women in drug tx

 

Roe & Schwartz, 1996

52

 

 

77

23

44

68

32

c

nr

Women in inpatient tx

 

Pomerantz, in progress

26

50

42.5

92.5

7.5

 

 

c

nr

Women in outpatient tx

 

Gold et al., 1994

105

30

40

70

30

 

 

c

nr

Intake interview in rx

 

Chu et al. 1999

74

34

26

60

41

89

28

 

 

Female inpatients of a PTSD & dissociative disorders unit

Nonclinical Samples

 

 

 

 

 

 

 

 

 

Bernet at el., 1993

624

36

 

64

 

30

nc

nr

College undergraduates

 

Belicki et al., 1994

68

 

 

55

45

 

 

nc

nr

College undergraduates

 

Kristiansen et al., 1995

113

25

26

51

49

61

93

nc

nr

Community sample, women

 

Elliott & Fox, 1994

484

30

14

44

56

 

19

nc

nr

College undergraduates

 

Van der Kolk & Fisler, 1995

36

 

 

42

58

75

 

nc

nr

Volunteers, terrible life experiences

 

Roesler & Wind, 1994

228

28

 

72

 

 

 

 

Triggered by M. Van Derbur disclosure

 

Grassian & Holtzen, 1996

42

19

28

47

53

 

 

nc

nr

Triggered by Father Porter disclosure

 

Golding et al., 1996

613

13

 

 

 

 

nc

nr

College undergraduates

Random Samples

 

 

 

 

 

 

 

 

 

 

Briere & Conte, 1993

450

 

 

59

41

 

 

c

r

In tx for CSA

 

Feldman-Summers & Pope, 1994

330

 

 

40

60

47

56

nc

r

Psychologists

 

Westerhof et al., in press

500

22

17

39

61

69

68

nc

r

Psychologists

 

Fish & Scott, 1999

423

17

38

55

45

 

44

nc

r

Counselors

 

Elliott & Briere, 1995

505

20

22

42

58

 

7

13

nc

nr

General population

 

Polusny & Follette, 1996

223

 

 

30

39

70

61

 

 

nc

nr

Psychologists

 

Melchert, 1996

553

18

 

82

 

 

nc

r

College undergraduates

 

Golding, 1995

663

14

 

 

 

 

nc

r

Telephone survey

Prospective Studies

 

 

 

 

 

 

 

 

 

Williams, 1994

129

38

 

62

100

0

nc

nr

Women with clinic documentation of CSA

 

Widom & Morris, 1997

1,114

37

 

63

100

 

nc

nr

Court-substantiated CSA

 

Burgess et al. 1995

22

14

27

41

59

100

0

c

nr

Daycare CSA

Other Studies

 

 

 

 

 

 

 

 

 

 

Kluft, 1997

19

68

 

32

100

100

c

nr

DID pts in tx; confirmed abuse

 

Goodman et al., 1995

1,652

4.5

45

50

50

 

 

c

nr

Ritual abuse allegations

Detailed Case Reports

 

 

 

 

 

 

 

 

 

Duggal & Stroufe, 1998

1

 

 

 

100

 

 

 

Subject of a prospective & unrelated study

 

Martinez-Taboaz, 1996

2

 

 

 

100

 

 

 

DID pts in tx; confirmed abuse

 

Viederman, 1995

1

 

 

 

100

 

 

 

Woman in rx

* Adapted from Table 7.7 in Brown et al. (1998).

= Percentage of participants with full amnesia who attempted and obtained independent corroboration.

KEY:

N      = sample size

F      = full amnesia/no memory for a significant period of time

P      = partial amnesia

F+P  = combined percentage of full and partial amnesia

No A = no amnesia; continuous memory

IC     = percentage of sample for which some sort of independent corroboration existed

Rx   = percentage of sample where memory recovery was associated with (but not necessarily caused by) therapy; percentage of sample where memory initially recovered in therapy

c/nc = clinical vs. nonclinical sample

r/nr =  random vs. nonrandom sampling

rx     =   therapy

Tx   =  treatment

e      = experimental group

c      = control group

CSA =  childhood sexual abuse

DID  = dissociative identity disorder

By 1999, over 68 studies had been published that document dissociative amnesia after childhood sexual abuse. In fact, no study that has looked for evidence of traumatic or dissociative amnesia after child sexual abuse has failed to find it. see: Brown, Scheflin, & Whitfield. (1999). Recovered Memories: The Current Weight of the Evidence in Science and in the Courts, Journal of Psychiatry & Law, 27, 5-156.

The reality of traumatic amnesia is further supported by investigations of memory and attention in carefully controlled laboratory settings.

For example, a study recently published in the prestigious journal Nature demonstrated that people have executive control processes that can prevent unwanted declarative memories from entering awareness. Anderson & Green, Suppressing Unwanted Memories by Executive Control, 410 Nature 366-369 (2001, March 15). See also Davis, Repression and the Inaccessibility of Affective Memories, 52 J. Personality & Soc. Psychol. 585-93 (1987). (Reviews laboratory research demonstrating that some individuals display limited accessibility to personal, real-life affective memories. The effect is particularly pronounced for experiences involving fear or embarrassment.)

References

Albach, F., Moormann, P. & Bermond, B. (1996). Memory recovery of childhood sexual abuse. Dissociation, 9(4), 261-273.

Belicki, K., Correy, B., Boucock, A., Cuddy, M., & Dunlop, A. (1994). Reports of sexual abuse: Facts or fantasies? Unpublished manuscript. Brock University , St. Catherines , Ontario .

Bernet, C. Z., Deutscher, R., Ingram, R. E., & Litrownik, A. J. (November 1993). Differential factors in the repression of memories of childhood sexual abuse . Poster presented at the Annual Convention of the Association for the Advancement of the Behavioral Therapy, Atlanta , GA.

Briere, J., & Conte, J. (1993). Self-reported amnesia for abuse in adults molested as children. Journal of Traumatic Stress , 6 (1), 21-31.

Burgess, A. W., Hartman, C. R., & Baker, T. (1995). Memory presentations of childhood sexual abuse. Journal of Psychosocial Nursing, 33 (9), 9-16.

Cameron, C. (1994). Women survivors confronting their abusers: Issues, decisions, and outcomes. Journal of Child Sexual Abuse, 3(1), 7-35.

Chu , J., Frey, L., Ganzel, B., & Matthews, J. (1999). Memories of childhood abuse: Dissociation, amnesia, and corroboration. The American Journal of Psychiatry, 156, 749-55.

Dollinger, S. J. (1985). Lightening-strike disaster among children. British Journal of Medical Psychiatry, 58 , 375-383.

Draijer, N. (1990). Seksuell misbruik van door verwanten: Een landelijk onderzoek naar de omvang, de aard, de gezinsachtergronded, de emotionele etekeniss en de psychische en psychosomatische gevolgen [Sexual abuse of girls by relatives: A nation-wide survey of the nature, emotional signs and psychological and psychosomatic sequelae]. Den Haag: Ministerie van Sociale Zaken en Verkgelegenheid.

Duggal, S., & Sroufe, L. A. (1998). Recovered memory of childhood sexual trauma: A documented case from a longitudinal study. Journal of Trauma Stress, 11(2), 301-321

Elliott, D. M., & Briere, J. (1995). Posttraumatic stress associated with delayed recall of sexual abuse: A general population study. Journal of Traumatic Stress, 8(4), 629-47.

Elliott, D. M., & Fox, B. (1994). Child abuse and amnesia: Prevalence and triggers to memory recovery . Paper presented at the Annual Meeting of the International Society of Traumatic Stress Studies, Chicago, IL .

Ensink, B. J. (1992). Confusing realities: A study of child sexual abuse and psychiatric symptoms . Amsterdam: VU University Press.

Feldman-Summers, S., & Pope, K. S. (1994). The experience of "forgetting" childhood abuse: A national survey of psychologists. Journal of Consulting & Clinical Psychology, 62(3), 636-39.

Femina, D. D. , Yeager, C. A., & Lewis, D. O. (1990). Child abuse: Adolescent records vs. adult recall. Child Abuse & Neglect, 14(2), 227-31.

Fish, V., & Scott, C. (in press). Childhood abuse recollections in a non-clinical population: Forgetting, secrecy, dissociation, and absorption.

Gold, S. N, Hughes, D., & Hohnecker, L. (1994). Degrees of repression of sexual abuse memories. American Psychologist, 49, 441-442.

Golding, J. M., Sanchez, R., & Sego, S. A. (1996). Do you believe in repressed memories? Professional Psychology, Research and Practice, 27(5), 427-37.

Goodman, G. S., Qin, J., Bottoms, B. L., & Shaver, P. R. (1995). Characteristics and sources of allegations of ritualistic child abuse. Final report to the National Center on Child Abuse and Neglect.

Grassian, S., & Holtzen, D. (1996, July). Memory of sexual abuse by a parish priest . Paper presented at Trauma and Memory: An International Research Conference. Portsmouth , New Hamsphire.

Herman, J. L., & Schatzow, E. (1987). Recovery and verification of memories of childhood sexual trauma. Psychoanalytic Psychology , 4 (1), 1-14.

Kluft, R. P. (1997). The argument for the reality of the delayed recall of trauma. In P. S. Applebaum, L. A. Uyehara, & M. Elin (Eds.), Trauma and memory: Clinical and legal controversies (pp. 25-57). New York : Oxford University Press.

Kristiansen, C. M., Felton, K. A., Hovdestad, W. E., & Allard, C. B. (1995). The Ottawa survivor's study: A summary of the findings . Unpublished manuscript.

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Martinez-Taboas, A. (1996). Repressed memories: Some clinical data contributing toward its elucidation. American Journal of Psychotherapy, 50(2), 217-30.

McFarlane, A. C. (1988). The longitudinal course of posttraumatic morbidity: The range of outcomes and their predictors. Journal of Nervous and Mental Disease, 176, 30-39.

Melchert, T. P. (1996). Childhood memory and a history of different forms of abuse. Professional Psychology, Research and Practice, 27(5), 438-46.

Polusny, M. A., & Follette, V. M. (1996). Remembering child sexual abuse: A national survey of psychologists' clinical practices, beliefs, and personal experiences. Professional Psychology: Research and Practice , 27(1), 41-52.

Pomerantz, J. (in progress). Memories of abuse: Women sexually traumatized in childhood . Unpublished manuscript, The Center for Trauma and Dissociation, Denver, CO.

Robins, L. N. (1966). Deviant children grown up: A sociological and psychiatric study of sociopathic personality. Baltimore , MD : Williams & Wilkins.

Roe, C. M., & Schwartz, M. F. (1996). Characteristics of previously forgotten memories of sexual abuse: A descriptive study. Journal of Psychiatry & Law, 24(2), 189-206.

Roesler, T. A.; & Wind, T. W. (1994). Telling the secret: Adult women describe their disclosures of incest. Journal of Interpersonal Violence, 9(3), 327-38.

Sargant, W., & Slater, E. (1941). Amnestic syndromes in war. Proceedings of the Royal Society of Medicine, 34, 757-764.

van der Kolk, B., & Fisler, R. (1995). Dissociation and the fragmentary nature of traumatic memories: Overview and exploratory study. Journal of Traumatic Stress , 8(4), 505-525.

Viederman, 1995

Wagenaar, W. A., & Groeneweg, J. (1990). The memory of concentration camp survivors. Applied Cognitive Psychology, 4, 77-87.

Westerhof, Y., Woertman, D., & Van der Hart, O. (in press). Forgetting childhood abuse: Feldman-Summers & Pope's (1994) study replicated among Dutch psychologists.

Widom, C. S., & Morris, S. (1997). Accuracy of adult recollections of childhood victimization: Part 2. Childhood sexual abuse. Psychological Assessment, 9(1), 34-46.

Widom, C. S., & Shepard, R. L. (1996). Accuracy of adult recollections of childhood victimization: Part 1. Childhood physical abuse. Psychological Assessment, 8(4), 412-21.

Wilkinson, C. B. (1983). Aftermath of a disaster: The collapse of the Hyatt Regency hotel skywalks. American Journal of Psychiatry, 140, 1134-1139.

Williams, L. M. (1994). Recall of childhood trauma: A prospective study of women's memories of child sexual abuse. Journal of Consulting and Clinical Psychology, 62 (6), 1167-76.

 

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