Biomedical subjects

Justin S Huthwaite

Publications and source records attributed to Justin S Huthwaite.

5 recordsLinked to original sources

PubMed2006

Structured cueing on a semantic fluency task differentiates patients with temporal versus frontal lobe seizure onset.

Patients with frontal lobe dysfunction (e.g., Huntington's disease) reportedly benefit more from cueing on measures of semantic fluency than do patients with damage to temporal lobe structures (e.g., Alzheimer's disease). This differential benefit from cueing suggests that different neurocognitive functions are impaired in these two groups. Patients with frontal lobe dysfunction are presumed to have difficulty with the executive aspects of this generative fluency task, whereas patients with temporal lobe impairment are limited by deficits in semantic memory. We studied the performance of patients with complex partial seizures of frontal or temporal lobe onset, as determined by video/EEG monitoring, on standard and cued measures of semantic fluency administered in a counterbalanced sequence across groups. These groups did not differ significantly in terms of age, education, gender, age at seizure onset, total number of antiepileptic drugs, or IQ, and all patients subsequently underwent surgery for intractable epilepsy. Patients with frontal lobe dysfunction (FL group) performed significantly worse than patients with temporal lobe impairment (TL group) on the standard semantic fluency paradigm (TL group: M=18.4, SD=4.7; FL group: M=11.1, SD=5.3), t(27)=-3.75, P<0.001. Nevertheless, results of an ANCOVA demonstrated that the FL group showed significantly greater performance improvement than the TL group when provided with a cued semantic fluency format, even after controlling for baseline differences in ability on the standard semantic fluency task (TL group: M=0.45, SD=3.8; FL M=9.4, SD=5.1), F(1,29)=12.37, P=0.002. These findings support previous research suggesting that frontal and temporal structures contribute uniquely to semantic generative fluency and suggest that using a combination of standard and cued semantic fluency tasks may help confirm localization of seizure onset in partial epilepsy by localizing the associated cognitive dysfunction.

Adult↗

PubMed2006

Declining medical decision-making capacity in mild AD: a two-year longitudinal study.

This is a report of a two-year longitudinal study comparing healthy older adult subjects (n = 15) and mild Alzheimer's disease (AD) patients (n = 20) using an objective performance measure of medical decision-making capacity (MDC). Capacity to consent to medical treatment was measured using the Capacity to Consent to Treatment Instrument (CCTI). The CCTI is a psychometric measure that tests MDC using a series of four core capacity standards: S1 (evidencing/communicating choice), S3 (appreciating consequences), S4 (providing rational reasons), and S5 (understanding treatment situation), and one experimental standard [S2] (making the reasonable treatment choice). For each standard, mild AD patients were assigned one of three capacity outcomes (capable, marginally capable, or incapable) based on cut-off scores derived from control group performance. At baseline, mild AD patients performed equivalently with controls on simple standards of evidencing a choice (S1) and making the reasonable choice ([S2]), but significantly below controls on complex standards of appreciation, reasoning, and understanding (S3, S4, and S5) (p < 0.02). Control performance was stable over time on all capacity standards. At one-year follow-up, the mild AD group did not show significant decline from baseline on any capacity standard. However, at two-year follow-up the mild AD group showed significant declines from baseline on the three complex standards (S3, S4, and S5) (p < 0.02), and a trend on one of the simple standards (S1). Over the two-year period, the proportion of marginally capable and incapable outcomes in the AD group increased substantially for four of the five standards (S1, S3, S4, and S5). Performance on [S2] remained stable over time in the AD group.We conclude that mild AD patients have impaired MDC at baseline, and demonstrate significant additional decline on complex consent abilities of appreciation, reasoning, and understanding over a two-year period. AD patients also show emerging impairment on the simple consent ability of evidencing choice at two-year follow-up. Capacity outcome data reflect similar declines over time for these four consent standards. The findings suggest the value of early assessment and regular monitoring at two-year intervals of MDC in patients with mild AD.

Aged↗

PubMed2005

Impairment and partial recovery of medical decision-making capacity in traumatic brain injury: a 6-month longitudinal study.

OBJECTIVE: To investigate empirically change in medical decision-making capacity (MDC) in patients with traumatic brain injury (TBI). DESIGN: Longitudinal study comparing control and TBI groups at hospitalization and at 6 months postinjury. SETTING: Inpatient brain injury rehabilitation unit. PARTICIPANTS: Twenty healthy controls and 24 patients with moderate to severe TBI. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: MDC was measured by using the Capacity to Consent to Treatment Instrument (CCTI). The CCTI evaluates performance on a series of 4 accepted consent abilities, or standards: S1 (evidencing/communicating choice), S3 (appreciating consequences), S4 (reasoning about treatment), and S5 (understanding the treatment situation and choices), and 1 experimental standard [S2] (making the reasonable treatment choice when the alternative choice is unreasonable). In addition, TBI patients were assigned 1 of 3 capacity outcomes (capable, marginally capable, incapable) for each standard. RESULTS: At hospitalization, TBI patients performed equivalently with controls on standards S1 and [S2] but significantly below controls on S3 ( P <.001), S4 ( P <.02), and S5 ( P <.001). At 6-month follow-up, TBI patients showed significant within-group improvement on these 3 standards (S3, S4, S5) but continued to fall significantly below controls on S3 ( P <.006) and S5 ( P <.001). A group by time interaction emerged on S5 ( P <.02). The TBI group showed increasing proportions of capable outcomes on all standards over the 6 months. CONCLUSIONS: Patients with TBI showed initial impairment and subsequent partial recovery of MDC over a 6-month period. Complex consent abilities of appreciation, reasoning, and understanding were significantly impaired in hospitalized acute TBI patients. At follow-up, TBI patients showed substantial recovery of reasoning and partial recovery of appreciation and understanding consent abilities. The study suggests the importance in the rehabilitation setting of serial evaluations of MDC in patients with TBI.

Adult↗

PubMed2003

Healthy older adult performance on a modified version of the Cognistat (NCSE): demographic issues and preliminary normative data.

Normative data for a healthy sample of older adults (n = 108) ranging in age from 60 to 96 are provided for the Cognistat, a mental status exam previously known as the Neurobehavioral Cognitive Status Examination (NCSE). A Cognistat Composite Score is also introduced that is intended to be used as a marker of general cognitive impairment, allowing the Cognistat to be used to match patients in terms of the severity of their cognitive dysfunction. The "screen and metric" approach of the Cognistat was abandoned in order to improve the reliability and standardization of this measure by administering the entire metric to all patients. The impact of demographic variables on Cognistat performance was examined, demonstrating that both age and education contribute uniquely to a number of Cognistat subtests as well as to the Cognistat Composite Score. This study highlights the importance of matching an examinee's demographic background to the normative sample with which his or her test score is being compared. Normative data were stratified accordingly by age and by both age and education. Current results indicate that the Cognistat is sensitive to normal aging and promises greater sensitivity to the impact of age than the commonly employed Mini-Mental State Examination (MMSE).

Aged↗

PubMed2002

Demographic characteristics and normative observations for derived-trail making test indices.

OBJECTIVE: The Trail Making Test (TMT) is a psychomotor task that is used routinely in clinical evaluations and consists of two parts: TMT-A and TMT-B. The purpose of the present study was to examine the relations of two derived-TMT indices with age, education, and gender and to establish normative data. BACKGROUND: Prior research has suggested that these derived indices provide purer measures of the executive skills required to complete TMT-B. It has also been suggested that these scores can be effectively used to detect cognitive impairment, and that they are relatively free from the impact of age. METHOD: Difference scores (B minus sign A) and ratio scores (B:A) were computed from the TMT performance of 285 adults who have no history of substance abuse or psychiatric or neurologic disorder and who are not currently being treated with any type of psychotropic medication. RESULTS: Subjects ranged in age from 18 to 90 years and in education level from 6 to 20 years. For the entire sample, (B minus sign A) scores ranged from 6 to 248 seconds (M, 62.15; SD, 49.44), and (B:A) scores ranged from 1.23 to 9.54 (M, 2.81; SD, 1.13). Significant correlations were noted with age and (B minus sign A) and (B:A) scores, accounting for 28% and 6% of the variance, respectively. Subjects were assigned to one of eight age groups, which were formed by decade. Univariate analyses of variance were significant for (B minus sign A) (p < 0.0001) and (B:A) (p < 0.0004) scores. Post hoc analyses indicated that the two oldest age groups had significantly larger (B minus sign A) scores than the younger age groups. However, post hoc analyses with (B:A) scores indicated that only the 70-79-year-old age group significantly differed from the three youngest age groups. No other age groups significantly differed from another on this measure. CONCLUSIONS: Normative data are presented for clinical use, and recommendations are made for future research. In addition, the current results suggest that normal aging has a significant impact on cognitive flexibility and indicate that previous suggestions for impairment cut-off scores based on the (B:A) ratio may result in erroneous classification of healthy older adults.

Adult↗