The Trail Making Test (TMT) is a well-established test sensitive to impairment in multiple cognitive domains. There has been ambiguity about which cognitive demands are placed on the patient by TMT Part B over and above those required to perform TMT Part A. In particular, cognitive flexibility and ability to maintain a complex response set have been 2 competing hypotheses. This study preliminarily examined which of these 2 abilities primarily contributes to Part B performance. A total of 121 clinically referred Veterans Affairs patients were administered the TMT, as well as other tests of executive and other cognitive functions. Regression analyses were used to examine which tests predicted Part B performance above and beyond Part A performance. The results provide preliminary support for TMT Part B performance being more sensitive to cognitiveflexibility (operationalized as Wisconsin Card Sorting Test [WCST], percent perseverative errors) than ability to maintain set (operationalized as WCST, failure to maintain set).

These results suggest that human sleep-deprivation deficits are not caused solely or even predominantly by prefrontal cortex dysfunction and that the paretal cortex, in particular, and other brain regions involved in verbal working memory exhibit significant sleep-deprivation vulnerability.

This study delineated patterns of alcohol use 1 year after traumatic brain injury (TBI) in a large, population-based, epidemiological, nonclinical sample, and identified predictors of heavy alcohol use in these individuals. Participants were 1,606 adults identified by review of a South Carolina statewide hospital discharge data set, on the basis of satisfying the Centers for Disease Control case definition of TBI, and were interviewed by telephone 1 year after TBI-related discharge. Alcohol use in the month prior to interview was classified according to categories from the Quantity-Frequency-Variability Index; heavy drinking was defined as nearly daily use with > or = 5 drinks at least occasionally, or at least three occasions with > or = 5 drinks. A polychotomous logistic regression with 3 response levels (heavy, moderate, and abstinent/infrequent/light drinking) was used to identify predictors of heavy drinking. Heavy drinking in the month prior to interview was reported by 15.4% of participants, while 14.3% reported moderate drinking and 70.3% reported abstinence or light/infrequent drinking. Risk factors for heavy drinking included male gender, younger age, history of substance abuse prior to TBI, diagnosis of depression since TBI, fair/moderate mental health, and better physical functioning. There was no association between drinking patterns and TBI severity.