The Louisville Twin Study (LTS) began in 1958 and became a premier longitudinal twin study of cognitive development. The LTS continuously collected data from twins through 2000 after which the study closed indefinitely due to lack of funding. Now that the majority of the sample is age 40 or older (61.36%, N = 1770), the LTS childhood data can be linked to midlife cognitive functioning, among other physical, biological, social, and psychiatric outcomes. We report results from two pilot studies in anticipation of beginning the midlife phase of the LTS. The first pilot study was a participant tracking study, in which we showed that approximately 90% of the Louisville families randomly sampled (N = 203) for the study could be found. The second pilot study consisted of 40 in-person interviews in which twins completed cognitive, memory, biometric, and functional ability measures. The main purpose of the second study was to correlate midlife measures of cognitive functioning to a measure of biological age, which is an alternative index to chronological age that quantifies age as a function of the breakdown of structural and functional physiological systems, and then to relate both of these measures to twins' cognitive developmental trajectories. Midlife IQ was uncorrelated with biological age (- .01) while better scores on episodic memory more strongly correlated with lower biological age (- .19 to - .31). As expected, midlife IQ positively correlated with IQ measures collected throughout childhood and adolescence. Additionally, positive linear rates of change in FSIQ scores in childhood significantly correlated with biological age (- .68), physical functioning (.71), and functional ability (- .55), suggesting that cognitive development predicts lower biological age, better physical functioning, and better functional ability. In sum, the Louisville twins can be relocated to investigate whether and how early and midlife cognitive and physical health factors contribute to cognitive aging.

中文翻译：

---

路易斯维尔双胞胎的中年研究：将认知发展与生物和认知衰老联系起来。

路易斯维尔双生子研究（LTS）始于1958年，成为认知发展的主要纵向双生子研究。LTS一直收集到2000年的双胞胎数据，此后由于缺乏资金，该研究无限期结束。现在，大多数样本年龄在40岁或以上（61.36％，N = 1770），LTS的儿童期数据可以与中年认知功能以及其他身体，生物学，社会和精神病学结果相关联。我们报告了两项预计将开始LTS中年阶段的试验研究的结果。第一项试点研究是一项参与者追踪研究，其中我们表明，大约有90％的路易斯维尔家庭（该研究为随机抽样）可以找到（N = 203）。第二项先导研究包括40次面对面访问，其中双胞胎完成了认知，记忆，生物识别，和功能能力测度。第二项研究的主要目的是将认知功能的中年测量值与生物学年龄的测量值相关联，生物学年龄的测量值是按年龄排序的另一种指标，该年龄根据结构和功能生理系统的崩溃来量化年龄，然后进行关联。这两种方法都可以测量双胞胎的认知发展轨迹。中年智商与生物学年龄（-.01）不相关，而情节记忆的更好分数与较低生物学年龄（-.19至-.31）密切相关。不出所料，中年智商与整个儿童期和青春期收集的智商指标呈正相关。此外，儿童期FSIQ分数的正线性变化率与生物学年龄（-.68），身体功能（.71），和功能能力（-.55），表明认知能力发展预示着更低的生物学年龄，更好的身体机能和更好的功能能力。总之，可以将路易斯维尔双胞胎搬迁，以调查早期和中年认知和身体健康因素是否以及如何促进认知衰老。