Studies have reported that the age-adjusted incidence of cognitive impairment and dementia have decreased over the past two decades. Aging is the predominant risk factor for Alzheimer's disease and related dementias and for neurocognitive decline. However, aging alone cannot explain changes in the overall age-adjusted incidence of dementia. The objective of this position paper was to describe the potential for cohort and period effects in cognitive decline and incidence of dementia. Cohort effects have long been reported in demographic literature, but starting in the early 1980s researchers began reporting large historical cohort trends in cognitive function. At the same time, period effects have emerged in the form of economic factors and stressors in early and midlife that may result in reduced cognitive dysfunction. Recognizing that aging individuals today were once children and adolescents and that research has clearly noted that childhood cognitive performance are associated with old-age cognitive performance, this review proposes the need to connect these cohort effects with differences in late-life functioning.

中文翻译：

---

队列和时期效应作为痴呆症趋势下降和认知老化的解释

研究报告称，在过去二十年中，认知障碍和痴呆症的年龄调整发病率有所下降。衰老是阿尔茨海默病和相关痴呆症以及神经认知能力下降的主要危险因素。然而，仅靠老龄化并不能解释经年龄调整的痴呆症总体发病率的变化。这份立场文件的目的是描述认知能力下降和痴呆症发病率的队列和时期效应的可能性。队列效应早已在人口统计学文献中得到报道，但从 1980 年代初开始，研究人员开始报告认知功能的大型历史队列趋势。与此同时，周期效应以经济因素和早年和中年压力源的形式出现，可能导致认知功能障碍减少。