Teuber and Weinstein (1954) (see cohort description in Chapter 5) studied 35 World War II veterans selected from 185 veterans who had penetrating missile injuries and loss of brain tissue and 12 controls from 101 veterans who had missile injuries of peripheral nerves but no brain injury. All veterans had sustained their injuries 5–8 years before the study. The 35 brain-injured were selected by identifying equal numbers of men with injuries in the anterior or posterior one-third of the brain and in the right or left hemisphere. The control group consisted of nine men with arm injuries and three with leg injuries. All the men were tested with the Seguin-Goddard Formboard Test, which was administered with the men blindfolded first in its normal position and then after a 180-degree rotation. Men with brain injuries took more time, made more errors, and recalled fewer forms than the controls.
Another study by Weinstein and Teuber (1957b) examined two groups of men: 62 who had loss of cerebral tissue due to penetrating head injury and 50 who had trauma of peripheral nerves. Preinjury Army General Classification Test (AGCT) scores, which had been administered on induction into the Army 13–15 years before the study, were available for all the men. Preinjury education level was determined by interview and from case records. The civilian edition of the AGCT was administered to all the study participants 10–12 years after their injuries. The findings indicate clearly that the change in AGCT score was significantly worse in the penetrating-injury group than in the peripheral-nerve–injured group. Furthermore, although the primary aim of the study was to investigate the connection between preinjury education and intelligence and intellectual deterioration after brain injury, the authors note that the findings were independent of any effects of differences in preinjury education or preinjury AGCT score.
Corkin et al. (1989) conducted a 30-year longitudinal study of 84 World War II veterans to determine the cognitive effects of penetrating head injury: 57 veterans who had penetrating head injury and 27 veterans who had peripheral nerve injury who were matched with respect to age and premorbid intelligence and education. The veterans were examined in the 1950s and in the 1980s. The veterans selected were those who had been seen by Teuber and Weinstein in New York (see Chapter 5 for Teuber’s cohort of World War II veterans). Both groups of veterans had received an average of 12 years of education before injury and were tested with the AGCT before injury. Total scores of 42 veterans were available from military records. Review of the preinjury AGCT total scores showed no differences between the two groups. Both groups were given two cognitive tests after injury: the AGCT and the Hidden Figures Test. The AGCT contains three subscales—vocabulary, arithmetic, and block-counting—and the Hidden Figures Test measures the ability to discriminate figures from background. Ten years after the end of the war, in the 1950s, the penetrating-injury group showed poorer performance on both cognitive tests than the peripheral-nerve–injured controls. Forty years after the war, in the 1980s (when the study was conducted), the penetrating-injury group exhibited even poorer performance on every cognitive measure except vocabulary, which remained constant. When the data were examined by brain region with computed tomography, the site of the injury exerted an even stronger effect. Veterans with injuries of the left parietal lobe had a significantly greater decrease on the vocabulary and arithmetic subscales, and those with lesions in other brain regions showed a greater decrease on other subscales or on the Hidden Figures Tests. Penetrating-injury subjects lost an average of 7.9 points from the 1950s to the 1980s, and those with peripheral nerve injury gained an average of 0.4 point. The decline was most pronounced in older subjects. The results suggested accelerated aging in those with penetrating head injury.