Final answer:
In middle adulthood, crystallized intelligence typically remains stable or can improve, as it is bolstered by accumulated knowledge and life experiences. Engagement in mental and physical activities has been shown to help sustain cognitive functions and delay the decline of fluid intelligence, which tends to start decreasing in later adulthood.
Step-by-step explanation:
When examining how crystallized intelligence changes in middle adulthood, it is found to be quite resilient and can even improve over time. During middle adulthood, which spans roughly from the mid-30s to the mid-60s, people continue to accumulate knowledge and experiences that contribute to crystallized intelligence. This type of intelligence involves the retrieval and use of learned knowledge and experience, which often remains stable or increases until the mid-50s, with some even showing stable to increasing scores on intelligence tests during this period.
Unlike crystallized intelligence, fluid intelligence—which encompasses problem-solving, reasoning, and memory—tends to decline in later adulthood. To delay cognitive decline in areas such as fluid intelligence, engaging in mental and physical activities has been shown to be beneficial. These activities help maintain cognitive function and reduce the chances of mild cognitive impairment and dementia.
Even as certain physical abilities and some aspects of cognitive function may show decline during middle adulthood, the growth in life experiences and accumulated wisdom often compensates for this. Therefore, while people may begin to develop chronic diseases like type 2 diabetes or experience a decline in physical fitness, the fortification of crystallized intelligence can continue to support cognitive health and adaptability throughout this stage of life.