assessment. There has also been a general lack of
practical clinical guidelines on which to base capacity
assessments. Until recently, clinicians have had to rely
almost exclusively on subjective clinical impressions
and brief mental status testing in reaching a judgment
regarding TCC.
Physician judgment has traditionally represented
the accepted criterion or gold standard for determining
TCC in medical and legal practice. However, studies
involving older adults and persons with AD have
raised the concern that physician judgments of TCC
may be both subjective and unreliable. Specifically,
experienced physicians have been found to be highly
inconsistent in their judgments of TCC in older adults
with mild AD. This inconsistency may reflect issues
of lack of clinical training, differing conceptual
approaches, and the conflation of mental status results
with capacity status in older adults. One response to
these issues of clinical accuracy and consistency in
capacity judgments has been the development of stan-
dardized assessment measures.IInnssttrruummeennttss ffoorr AAsssseessssiinngg TTCCCC
In recent years, investigators have used the above
models of TCC to develop standardized, norm-
referenced psychometric instruments for assessment of
TCC in different patient populations. These instru-
ments include the MacArthur Competence Assessment
Tool for Treatment (MacCAT–T), the Hopemont
Capacity Assessment Instrument, and the Capacity to
Consent to Treatment Instrument (CCTI). These stan-
dardized measures assist clinicians by offering specific
definitions of the TCC construct and by operationaliz-
ing standards or thresholds for testing capacity. In
addition to measuring capacity performance, some
instruments also identify capacity status (capable, mar-
ginally capable, or incapable) using cut scores derived
from control performance. Thus, these measures pro-
vide objective, norm-referenced information concern-
ing an individual’s TCC that can inform and guide
clinical decision making.
The limitations of these assessment instruments
should also be considered. First, instrument-based
deficits in TCC should not be construed as necessarily
reflecting clinical or legal impairments or incompe-
tency. Second, and related, clinical determination of
TCC is ultimately a judgment made by a clinician and
not an instrument performance score. Assessment
instruments can provide objective information aboutconsent abilities but are not substitutes for clinical judg-
ment. No capacity instrument can satisfactorily take
into account the myriad medical, legal, ethical, and
social considerations that inform a clinical or legal
capacity judgment. For this reason, standardized mea-
sures of TCC are intended to support, but certainly not
replace, the decision making of the clinician.Research on TCC in Clinical Populations
Impairment and loss of TCC have been studied in mul-
tiple clinical populations, including persons with schiz-
ophrenia and other psychiatric illnesses, Alzheimer’s
disease (AD), mild cognitive impairment (MCI),
Parkinson’s disease (PD), and traumatic brain injury
(TBI). Initial pioneering clinical studies of TCC were
carried out in psychiatric populations by Appelbaum,
Roth, Grisso, and colleagues and have documented
clearly the effects of mental illness on informed con-
sent capacities in these patients. Over the past 15 years,
there have been an increasing number of studies of
TCC in older adult populations with dementia. Due to its
relentless progressive nature and the well-characterized
stages of neurocognitive and functional change, AD has
proven to be a useful prism for understanding impair-
ment and loss of TCC. Studies have shown that the
minimal standards of consent capacity, such as express-
ing choice (S1) and making a reasonable choice [S2],
are relatively preserved in patients with mild to moder-
ate AD, whereas the clinically relevant standards of
appreciation (S3), reasoning (S4), and understanding
(S5) already show significant impairment. TCC also
shows significant longitudinal decline over a 2-year
period in patients with mild AD. A very recent study
has suggested that older patients with MCI, the pro-
drome or transitional stage to AD, also experience sig-
nificant deficits in TCC. Other studies have identified
deficits in TCC in patients with PD and cognitive
impairment and dementia. In contrast to these dementia
studies, an investigation of TCC in moderate to
severely injured patients with TBI found significant ini-
tial impairment but also subsequent partial recovery of
consent abilities 6 months following TBI. Thus, trajec-
tories of consent capacity impairment and change over
time can differ enormously across disease states.CCooggnniittiivvee SSttuuddiieess ooff TTCCCC
TCC assessment instruments have also provided
a useful psychometric criterion for investigating theCapacity to Consent to Treatment——— 53C-Cutler (Encyc)-45463.qxd 11/18/2007 12:41 PM Page 53