Division of Cognitive and Behavioral Neurology, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Neuroimage. 2011 Jan 1;54(1):427-38. doi: 10.1016/j.neuroimage.2010.08.006. Epub 2010 Aug 7.
One mechanism that may allow older adults to continue to successfully perform certain cognitive tasks is to allocate more resources than their younger counterparts. Most prior studies have not included individuals beyond their 70s. Here, we investigated whether compensatory increases in neural activity previously observed in cognitively high-performing young-old adults would continue into old-old age. Event-related potentials were recorded from 72 cognitively high performing subjects, aged 18 to 96 years old, while they participated in a subject-controlled novelty oddball paradigm in which they determined viewing duration of standard, target, and novel visual stimuli. Compared to young and middle-aged subjects, both young-old and old-old subjects exhibited an impairment of preliminary mismatch/match detection operations, indexed by an attenuated anterior N2 component. This may have placed a greater burden on the subsequent controlled decision-making process, indexed by the P3, necessitating the allocation of more resources. The relationship between age and resource allocation, as measured by P3 amplitude, from midlife to very old age (45-96 years old) followed an inverted u-shaped curve (quadratic function). It peaked between the late 60s and early 70s. Thereafter, there was an inverse relationship between age and resource appropriation. This relationship remained significant after controlling for differences in task performance and MMSE. Examining the size of the P3 component across different age groups suggests that although cognitively high performing adults in their early 80s exhibit a reduction in P3 amplitude, they have a relatively well-preserved capacity to appropriate resources. However, by the late 80s, there is a robust decline (relative to young-old adults) in the size of the P3. Our results indicate that when carrying out controlled processing linked to directing attention to salient events, cognitively high performers reach the boundary of their capacity, albeit relatively late in life. This limits their ability to appropriate additional resources as compensatory activity for age-related impairments in earlier visual processing, and suggests that such a mechanism does not tend to "survive" old-old age.
一种可能使老年人继续成功执行某些认知任务的机制是分配比年轻成年人更多的资源。大多数先前的研究都没有包括 70 多岁以上的个体。在这里，我们研究了在认知表现较高的年轻老年人中先前观察到的神经活动代偿性增加是否会持续到老年。我们记录了 72 名认知表现较高的受试者的事件相关电位，年龄在 18 岁至 96 岁之间，他们参与了一个由受试者控制的新颖性奇偶校验范式，在该范式中，他们确定了标准、目标和新颖视觉刺激的观看持续时间。与年轻和中年受试者相比，年轻老年人和老年老年人的初步不匹配/匹配检测操作都受到损害，表现为前 N2 成分减弱。这可能对随后的受控决策过程造成更大的负担，由 P3 表示，这需要分配更多的资源。从中年到非常老年（45-96 岁），年龄与资源分配的关系（以 P3 幅度衡量）遵循倒 U 形曲线（二次函数）。它在 60 多岁到 70 岁出头之间达到峰值。此后，年龄与资源分配呈反比关系。在控制任务表现和 MMSE 差异后，这种关系仍然显著。通过检查不同年龄组的 P3 成分大小，我们发现，尽管认知表现较高的成年人在 80 岁出头时 P3 幅度降低，但他们仍然具有相对较好的资源分配能力。然而，到 80 岁后期，P3 的大小会出现明显下降（相对于年轻老年人）。我们的结果表明，当执行与将注意力引向显著事件相关的受控处理时，认知表现较高的成年人会达到其能力的极限，尽管这是在生命后期。这限制了他们为适应与早期视觉处理相关的年龄相关损害而适当增加资源的能力，并表明这种机制不会“持续”到老年。
