While recognition of stages involving cognition in the developing child are universal--although much disagreement exists regarding the nature and substance of those stages--the study of cognitive change in adulthood becomes mired in the various definitions and philosophical views proposed by the respective theorists and researchers (Woolf, 1998). Structuralism, for instance, views cognitive change as unidirectional, whereas a life-span developmental theorist views it as multidirectional. This presents differences in not only how cognitive development is viewed, but as Woolf related, it presents differences in how it is studied, which portends even greater future debate.

The understanding as to who is right must be viewed from the multidimensional perspective of cognitive development (Woolf, 1998). It was Horn (1970, as cited in Woolf; 1982, as cited in Cavanaugh & Blanchard-Fields, 2002) who proposed that intelligence is composed of the combination of genetically-based skills (fluid intelligence) and experientially-based skills (crystallized intelligence), giving intelligence bidimensional properties. Schaie (1970, as cited in Woolf) broke Horn’s categories down further: Crystallized intelligence includes verbal meaning, space, reasoning and number, whereas fluid intelligence composes word fluency. Of course, cognitive development must also include memory, which would compose the dimensions of declarative memory--referring to events, facts, and concepts, or knowing “what”--and procedural memory--referring to skills and related behaviors, or knowing “how” (Kellogg, 1995). Schaie also pointed out that psychomotor speed must be considered as well as cognitive ability. All these factors lend reason to the multidimensional view.

Incidentally, these points show the viability of psychology in the study of cognitive development: “Although a scientific approach to cognition assumes that perceiving and thinking depend on brain functioning, there will always be a need for a level of explanation in which cognitive concepts play a role. Cognitive science will no more be replaced by physiology than the theory of evolution has been replaced by biochemistry” (Garnham, 1991).

Nonetheless, facts do generically exist. According to most studies, cognitive abilities are greatest between ages 30 and 50, where they level off during the 50s and into the 60s (American Federation for Aging Research, AFAR, 2003). The decline at that point, according to AFAR, is minimal, and does not become noticeable until the 70s or beyond.

The most common pathological roadblock to maintaining memory function is Alzheimer’s disease (AD). Studies have increasingly shown that this is largely preventable before the fact and possibly even after its onset in the early stages (Khalsa, 1997). For instance, compelling evidence exists showing that nutritional supplements appropriate to the applicable neural functions can increase the levels of brain catecholamines and protect against oxidative damage, thereby reducing neuronal damage (Sano et al., 1997).

Regarding the detection of risk, it actually may be that it can be detected early as the period of fetal development in the individual (National Institute of Health, 1999). Signs of AD or dementia, however, can be detected early in the onset of AD if signs of mild cognitive impairment are watched for and noted (Grundman et al, 2004). This is critical because the resulting widespread atrophy of the cerebral cortex, hippocampus, and other areas will result in progressive cognitive loss, including memory loss, confusion, depression, hallucinations, and delusions, and eventually premature death (Kalat, 2001).

Cavanaugh and Blanchard-Fields (2002), in fact, pointed out that the study of the cognitive processes in aging must be made with the distinction between normal and abnormal processes. The optimal level of development, therefore, is a very individual thing in the adult years. So many more factors seem involved than in the childhood years, for which Piaget could much more definitely attach age ranges to his stages of cognitive development. While there is apparently “no association between age and wise answers” (Cavanaugh & Blanchard-Fields, p. 290), pathology likely has more to do with drastic changes in cognitive abilities than does simple aging.

The fact is, there are no simple answers to all the questions and challenges thrust forth in the field. The variability of factors abound, not only individually, but among societies and cultures, and the conventions by which they conduct their affairs, which impose complexities that are difficult to discern and describe. Even if a cognitive science of aging were possible, constructing it would present monumental challenges.


American Federation for Aging Research. (2003). What cognitive changes take place with age? New York: Author. Retrieved March 1, 2004, from http://www.infoaging.org/b-neuro-1-what.html#top.

Cavanaugh, J. C., & Blanchard-Fields, F. (2002). Adult development and aging (4th ed.). Belmont, CA: Wadsworth.

Garnham, A. (1991). The mind in action: A personal view of cognitive science. New York: Routledge.

Grundman, M., Petersen, R. C., Ferris, S. H., Thomas, R. G., Aisen, P. S., Bennett, D. A., et al. (2004, January). Mild cognitive impairment can be distinguished from Alzheimer disease and normal aging for clinical trials. Archives of Neurology, 61(1), 59-66.

Kalat, J. W. (2001). Biological psychology (7th ed.). Belmont, CA: Wadsworth.

Kellogg, R. T. (1995). Cognitive psychology. Thousand Oaks, CA: Sage.

Khalsa, D. S. (1997). Brain longevity: The breakthrough medical program that improves your mind and memory. New York: Warner Books.

National Institute of Health, National Institute on Aging. (1999, December 13). Research provides further support for lifelong influences on brain and cognitive health. Washington, DC: Author. Retrieved March 1, 2004, from http://www.alzheimersupport.com/library/showarticle.cfm?ID=1002.

Sano, M., Ernesto, C., Thomas, R. G., Klauber, M. R., Schafer, K., Grundman, M., et al. (1997, April 24). A controlled trial of selegiline, alpha-tocopherol, or both as treatment for Alzheimer's disease. The Alzheimer's Disease Cooperative Study. New England Journal of Medicine, 336(17), 1216-1222.

Woolf, L. M. (1998). Theoretical perspectives relevant to developmental psychology:
A discussion of cognitive changes associated with old age within the framework of the first three sections. Webster University. Retrieved March 1, 2004, from http://www.webster.edu/~woolflm/cognitions.html.

Author's Bio: 

Lora Morrow is a neuropsychological counselor and President and Director of Positive Personal Modification Institute. Visit her website on Conquering Stress Today at http://www.conquerstresstoday.info .