Common symptoms of memory changes during the lifetime in healthy people generally start gradually beginning with those associated with episodic memory i.e. forgetting names of people or details of personally experienced events. While semantic memory does not decline in the same way and can in fact be equal to those of younger people, aging adults typically access general knowledge and information more slowly (Dixon et al., 2006).This is a sign of declining working memory which encompasses processing speed, attentional capability/distractibility and problem solving (Dixon et al., 2006; Richmond et al., 2011). Another type of memory change may stem from a decline in sensory acuity. For example, loss of vision, hearing, taste and smell would all impact how stimuli are encoded and will contribute to additional attentional interference (Wolfe & Horowitz, 2004)
Compared with expected changes in memory functioning over the lifespan, pathological conditions such as anterograde amnesia and loss of semantic memory are much more debilitating. Since typically developing memory decline is gradual and centers around past experiences rather than general knowledge, people are often able to adapt to their “forgetfulness” with the assistance of formal and informal compensatory strategies such as more effortful attention, associative learning of new information, making to-do lists, keeping a journal and/or relying on another close individual to fill in missing pieces of stories and events (Dixon et al., 2006)
While typically aging adults may make a to-do list but have to spend time trying to find where they left it, in the case of anterograde amnesia, this sort of strategy would be ineffective. This is because these individuals would have no memory of even making a list since they have lost the ability to form new memories (Squire & Wixted, 2011). People with this condition are likely to become easily confused in social situations involving unfamiliar people since they will not retain any introductory information provided.
Loss of semantic memory would also be more negatively impactful than loss of episodic memory because an individual would lose the ability to make sense of objects in their everyday environment. For example, they make not be able to identify what a television or a toilet is or what each item is used for. As is the case with anterograde amnesia, compensatory strategies that are effective for typical aging memory decline could not be used for semantic memory loss since the individuals would not be able to engage in metamemory cognitions that would enable them to identify their areas of deficit and the most appropriate strategies to address these (Squire & Wixted, 2011). In addition, in both conditions, the individual would require a high level of external support to live safely.
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