Characteristics of impaired awareness
after traumatic brain injury
MARK SHERER,
1,2
CORWIN BOAKE,
3,1
ELLEN LEVIN,
1,2
BERNARD V. SILVER,
1,2
GEORGE RINGHOLZ,
2
and WALTER M. HIGH, Jr.
2,1
1
The Institute for Rehabilitation and Research
2
Baylor College of Medicine, Houston, TX
3
University of Texas Health Science Center at Houston, Houston, TX
(Received May 13, 1997; Revised September 19, 1997; Accepted November 17, 1997)
Abstract
Impaired awareness of the effects of brain injury is a commonly observed and poorly understood finding in
traumatic brain injury survivors. Nonetheless, impaired awareness has been identified as a major factor in
determining outcome for traumatic brain injury survivors. Review of previous studies of impaired awareness in this
patient population revealed a number of preliminary findings regarding the nature of this phenomenon. The present
paper presents the results of 2 new studies with a total of 111 traumatic brain injury patients conducted to bring
further clarity to this area. Findings confirmed and extended many results of previous investigations. Specific
findings included patient overestimation of functioning as compared to family member ratings, patient report of
greater physical than nonphysical impairment, greater patient–family agreement on specific ratings of patient
functioning than on general ratings, greater agreement of family and clinician ratings of patient functioning with
each other than with patient self-ratings, and partial disagreement of different methods of measuring impaired
awareness. (JINS, 1998, 4, 380–387.)
Keywords: Impaired awareness, Traumatic brain injury, Characteristics, Measurement, Awareness Questionnaire
INTRODUCTION
Impaired awareness of deficits is a frequent finding after
acquired brain injury (Goldstein, 1939; Weinstein & Kahn,
1955). Such impaired awareness has been described in
patients with brain injury due to stroke, dementia, and trau-
matic brain injury (McGlynn & Schacter, 1989). Clinicians
working to rehabilitate patients who have suffered trau-
matic brain injury generally agree that impaired self-
awareness significantly complicates the rehabilitation process
(Ben-Yishay et al., 1985; Prigatano & Fordyce, 1986). Con-
sequently, there has been interest in developing methods of
assessing unawareness so that its effect on rehabilitation out-
come can be studied and the efficacy of treatment methods
aimed at improving awareness can be assessed.
Previous studies of impaired awareness in patients with
traumatic brain injury have measured awareness in a number
of ways using several different questionnaires and rating
scales. These studies have produced a variety of prelimi-
nary findings regarding the nature of impaired awareness.
Some of these findings are inconsistent across studies or
have not yet been replicated. The apparent inconsistency of
some of these findings may be the result of the different
ways that awareness has been measured in the various stud-
ies. There has been only very limited investigation of the
comparability of different methods of measuring aware-
ness. The present paper presents a comprehensive review of
previous findings regarding the nature of impaired aware-
ness after traumatic brain injury. Methodologies used to mea-
sure impaired awareness are also reviewed. Finally, the
results of two new investigations of the characteristics of
impaired awareness after traumatic brain injury are presented.
Characteristics of Impaired Awareness
Clinical observation suggests that impaired awareness after
traumatic brain injury is a complicated phenomenon. Some
patients, particularly in the acute period, may be unaware
that they have suffered any injury at all. Other patients ad-
Reprint requests to: Mark Sherer, Mississippi Methodist Rehabilita-
tion Center, 1350 East Woodrow Wilson, Jackson, MS 39216. USA. E-mail:
marks@mmrcrehab.org
Journal of the International Neuropsychological Society (1998), 4, 380–387.
Copyright 1998 INS. Published by Cambridge University Press. Printed in the USA.
380

mit to some deficits but fail to perceive the likely impact of
these deficits on their daily activities. Still other patients
seem keenly aware of postinjury changes and experience
significant depression. Empirical investigation of the na-
ture and course of impaired awareness in traumatic brain
injury is still at an early stage. However, previous studies
have examined some characteristics of impaired awareness.
Findings regarding the neuroanatomic basis of impaired
awareness after traumatic brain injury are quite limited. Since
traumatic brain injury is known to produce diffuse cerebral
damage, it is difficult to study the contribution of damage
to any particular cerebral region to impaired awareness. In
patients with focal lesions, it is thought that the frontal lobes
(Damasio & Anderson, 1993; Stuss, 1991) and the right
hemisphere (Heilman et al., 1993) have special roles in self-
awareness. To date, no study has attempted to examine the
possible association between amount of frontal lobe injury
after traumatic brain injury and degree of impaired aware-
ness. Two studies have examined the possible contribution
of right hemisphere lesions. Ranseen et al. (1990) found
greater unawareness in traumatic brain injury patients with
focal right hemisphere injuries as compared to those with
focal left hemisphere injury or diffuse injury. Prigatano and
Altman (1990) failed to find a greater incidence of right
hemisphere lesions in patients who overestimated their be-
havioral competencies as compared to those who did not.
However, patients with more identifiable lesions on CT or
MRI scan had poorer awareness than those with fewer le-
sions even though the groups did not differ on mean Glas-
gow Coma Scale score. Clinical experience suggests that
patients with more severe brain injury may experience greater
impairment of their self-awareness. However, three studies
that have investigated this issue (Allen & Ruff, 1990; An-
derson & Tranel, 1989; Gasquoine, 1992; Prigatano & Alt-
man, 1990) failed to find an association between neurologic
indices of severity of injury and degree of unawareness.
These results may be an artifact of the restricted range of
severity used in most studies. Levin et al. (1987) did find
that clinician ratings of patients’ accuracy of self-appraisal
were related to severity of injury with more severely in-
jured patients showing greater impairment.
Clinical experience also suggests that impaired aware-
ness may be related to patients’ general cognitive and
emotional functioning. Studies of the association between
severity of cognitive deficits and impaired awareness have
yielded inconsistent results. One study (Anderson & Tranel,
1989) found that greater cognitive impairment was associ-
ated with poorer self-awareness, while other studies have
found no association (McKinlay & Brooks, 1984; Priga-
tano & Altman, 1990). Studies of the relationship of emo-
tional functioning and awareness have found that patients
who admit to more impairment report a greater level of emo-
tional distress (Gasquoine, 1992; Godfrey et al., 1993;
Heaton & Pendleton, 1981).
Impaired awareness is not a global deficit. Degree of im-
pairment appears to depend on the area of functioning as-
sessed and the type of item used to make the assessment.
Traumatic brain injury survivors have been found to be more
aware of their physical deficits than their nonphysical
(cognitive and emotional) impairments (Anderson &
Tranel, 1989; Gasquoine, 1992; Hendryx, 1989; McKinlay
& Brooks, 1984; Prigatano, 1996; Prigatano et al., 1990).
Further, one study (Gasquoine, 1992) found that patients
were more likely to report deficits when asked specific ques-
tions about their functioning than when asked general or
open-ended questions.
Measurement of Impaired Awareness
To date, four methods of operationalizing impaired aware-
ness have been used. Three of these approaches involve com-
paring patient self-report of cognitive, physical, social, and
other areas of functioning to some other standard. It is as-
sumed that patients with impaired self-awareness will rate
their abilities as better or more intact than the standard. The
discrepancy between the patient’s self-rating and the stan-
dard is considered to be a measure of the degree of patient
unawareness. One such method is comparison of the pa-
tient’s self-rating to the rating of a family member (Fordyce
& Roueche, 1986; Hendryx, 1989; McKinlay & Brooks,
1984; Prigatano, 1996; Prigatano et al., 1990; Prigatano &
Altman, 1990; Walker et al., 1987). As expected, results of
studies using this method consistently find that traumatic
brain injury survivors rate themselves as less impaired than
do family members. A possible threat to the validity of this
method of measuring awareness would be inability of fam-
ily members to accurately rate patients’ abilities. Romano
(1974) found that some families deny the severity of pa-
tients’ deficits and McKinlay and Brooks (1984) found that
family member personality characteristics affect their rat-
ings of patient functioning.
Another standard to which patients’ self-ratings may be
compared is the judgment of clinicians who are familiar
with the patient’s functioning (Fordyce & Roueche, 1986;
Gasquoine, 1992; Gasquoine & Gibbons, 1994; Heilbron-
ner et al., 1989; Ranseen et al., 1990). Studies using this
approach have found that patients rate themselves as less
impaired than do clinicians. Clinician emotional response
to the patient could be a threat to the validity of this method
(Heilbronner et al., 1989).
The third standard of comparison to which patients’ self-
ratings may be contrasted is the patient’s performance on
objective measures of cognitive functioning (Allen & Ruff,
1990; Anderson & Tranel, 1989; Heaton & Pendleton, 1981).
Studies using this method have generally found that trau-
matic brain survivors underestimate the severity of deficits
that they show on neuropsychological tests. Allen and Ruff
(1990) found that while controls were generally more ac-
curate in their self-ratings than head-injured patients, they
also overestimated their true abilities on some tasks.
All methods of measuring awareness that use patient self-
ratings depend on patients having some capacity to reliably
rate their abilities even though such ratings are likely to be
overestimates. Clearly, such an assumption is not warranted
Impaired awareness 381