VOL 19, NO. 4, 1993 Sensory Gating and Inhibitory Function in Late-Life Schizophrenia 733 by Joan M. McDowd, Diane L. Filion, M. Jackuelyn Harris, and David L. Brail Abstract Although similarities between the cognitive deficits observed in schizophrenia and those observed in aging have been recognized for over 50 years, little work has been done to directly examine these similarities or their im- plications for late-life schizo- phrenia. We review studies of prepulse inhibition, habituation, latent inhibition, and negative priming that indicate marked similarities in the patterns of deficits observed in schizo- phrenia and in aging. We also present new data from prelimi- nary studies of prepulse inhibi- tion and negative priming in which we compared young nor- mal controls, older adult normal controls, and late-life schizo- phrenia patients. For both meas- ures, both schizophrenia patients and older adults showed an in- hibitory deficit relative to young controls. In the case of negative priming, older schizophrenia pa- tients showed evidence of greater inhibitory dysfunction than did normal older adults, suggesting that older schizophrenia patients suffer a deficit resulting from the combined effects of schizo- phrenia and aging. The implica- tions of these results and direc- tions for future research are discussed. Information-processing and atten- tional dysfunctions have long been identified as fundamental cognitive deficits in early-onset schizophrenia patients (e.g., Gjerde 1983; Mirsky and Duncan 1986; Anscombe 1987). It is interesting to note that strik- ingly similar dysfunctions have been reported in association with normal aging (e.g., Plude and Hoyer 1985; McDowd and Birren 1990); that is, both schizophrenia and aging are characterized by deficits in the efficiency with which information is encoded and processed. In both populations, these deficits may result in slowed processing, increased distractibility, and inefficient allocation of atten- tional resources. Saccuzzo observed these similarities in 1977. Echoing Cameron's (1939) proposal, he sug- gested that much could be learned about the cognitive deficits specific to schizophrenia from a systematic study of both states, schizophrenia and normal aging. According to Saccuzzo, what Cameron and per- haps others since then failed to realize, however, [is] the potential value of system- atically determining at what point the similarity between schizophrenia patients and the elderly ends. By determining the ways in which schizo- phrenia patients and the elderly are similar and those in which they are not, researchers can separate those experimental tasks uniquely related to schizo- phrenia from those that are re- lated to other forms of pathol- ogy and deterioration. [Saccuzzo 1977, p. 597] Saccuzzo's point is well taken in any analysis comparing cognitive function in schizophrenia patients and older adults. Although the two groups appear similar on some variables, they are obviously very different on others. Schizo- phrenia is an acute or chronic psy- chopathological disorder that is associated with a variable course. Aging is inevitably a chronic proc- ess that is part of normal devel- Reprint requests should be sent to Dr. J.M. McDowd, Dept. of Psychol- ogy, Pomona College, 550 N. Harvard Ave., Claremont, CA 91711. Downloaded from https://academic.oup.com/schizophreniabulletin/article-abstract/19/4/733/1888854 by guest on 15 February 2019