Part II: Aging: Body Structures and Body Functions: Introduction

Section 1: Normal Age-Related Changes

Part I of this text considered the sociocultural factors that affect late life, as well as theoretical considerations. The focus now turns to individuals, and to the issues that affect occupations and performance.

Throughout life, people's bodies change. These changes affect both structure and function of specific systems as well as the organism as a complex whole. When people are young, these changes typically involve growth and acquisition of new skills. In later life, the normal course of aging involves many gains—wisdom, experience, patience, perspective—but also decrements in function. Joints wear out, senses are dulled by exposure to sensory input, and even the most physically fit individuals lose some musculoskeletal and cardiovascular capacity.

Both the Occupational Therapy Practice Framework (American Occupational Therapy Association, 2014) and the International Classification of Function (World Health Organization, 2001) acknowledge that an individual's ability to participate fully in life is dependent to some extent on his or her biological and psychological function. A clear understanding of normal physiological development is one essential factor in a therapist's ability to frame effective interventions to support meaningful life.

The next five chapters address this topic. Each considers a major body system and provides an overview of the normal changes that accompany aging. These are changes that are very likely to affect every older adult to some extent, although individuals experience such change to different degrees and in different systems. So, for example, almost every older adult will need eyeglasses for near vision, but some require them by age 40, while others may not need them until a decade later. Every older adult will lose muscle mass and cardiovascular capacity, but marathon runners are likely to experience slower loss (and from a greater initial capacity) than sedentary individuals.

In reading these chapters, some specific considerations are important to keep in mind:

1. The various systems change to varying degrees for particular individuals.

2. There is an interaction among these changes. Although they are presented here as if these systems function independently, the reality is far more complex.

3. These changes occur in the context of the sociocultural factors described in Chapters 1 through 6.

4. And perhaps most important, these changes are only loosely related to alteration in occupation and participation. Some individuals are able to find ways to manage change such that valued activities can be continued into very old age. Others struggle to cope with very minor differences in physical, cognitive, or sensory capacity.

Subsequent chapters consider some of the reasons that individual coping skills vary and address strategies for supporting normal development in later life to the greatest extent possible.