Memory constitutes the basis of our continuity as human beings over time. When memory fails, our lives get knocked out of balance. The loss of short-term memory makes us unable to remember today's events and turn them into long-term memories, and, as Sangram Sisodia and Rudolph Tanzi, authors of "Alzheimer's disease," point out, the loss of working memory can hinder the completion of the simplest tasks, such as holding a phone number in our heads for the 5 seconds it takes to reach for the phone.
Alzheimer's Disease
Alzheimer's is a form of dementia that arises when plaque forms in the hippocampus, the brain's main center for storage-based short-term memory, reports professors Sisodia and Tanzi of the Ellison Medical Foundation. The formation of plaque in the brain prevents new experiences from moving from the sensory systems to the brain's storage facilities. This causes the neurons in the hippocampus to wither and die. A smaller and clotted hippocampus will not only hinder storage of information for the short term, it will also prevent new information from moving into the cerebral cortex, an outer brain region that normally stores information for the long term.
Self-Fulfilling Prophecy
Believing that memory gets worse as you get older can trigger memory loss in elderly individuals, reports a North Carolina research team in the April 2009 issue of "Experimental Aging Research." The team found that elderly individuals who were told that older people score lower on memory tests or have reduced memory capacities fared much worse on memory test than individuals who were primed to disbelieve the negative stereotype. Believing that memory will fail with age thus becomes a self-fulfilling prophesy, says team member Tom Hess. The researchers speculate that negative beliefs about your own mental capacities hinder your mental capacities by inducing chemicals that block brain activity.
Inability to Filter Out Distractions
Researchers used to believe that the ability to focus causes short-term memory loss in elderly individuals. It is, however, much more likely to be the inability to filter out distractions that is the key to poor memory, reports a research team in the September 11, 2005 online issue of "Nature Neuroscience." As we get older, we do not normally becomes less able to focus on relevant information; we become less able to set aside irrelevant information. The distracting noise can cause confusion and can affect the capacity of working memory. People who cannot filter out distractions have to sort through relevant and irrelevant information before they can start manipulating the relevant information. The researchers speculate that their findings may lead to better medical treatments of short-term memory loss. The standard variety medications used to treat memory loss in elderly individuals just improve people's ability to stay focused, but that really isn't the problem that requires treatment, the researchers say.
Attention Deficit Hyperactivity Disorder
Attention deficit hyperactivity disorder, or ADHD, affects people's ability to stay focused. This, in turn, affects working memory and clarity of thought. As it turns out, Children with ADHD are not simply ill-behaved; they demonstrate abnormal brain activity patterns, reports a University of Washington research team in the March 2009 issue of "The Journal of Abnormal Psychology." The researchers found that the striatal brain region in the mid-brain, which motivates people to carry out pleasurable or rewarding behavior, stays activated in children with ADHD. A mechanism in a higher brain area called "the anterior cingulate," which normally deactivates neurons in the striatal brain region, fails to kick in. When this deactivation mechanism fails, people are unable to concentrate on less rewarding or more boring exercises, the researchers say.
References
- "Alzheimer's disease: advances in genetics, molecular and cellular biology"; Sisodia and Tanzi; 2007
- "Experimental Aging Research"; Moderators of and Mechanisms Underlying Stereotype Threat Effects on Older Adults' Memory Performance; Hess, et al.; April 2009
- "Nature Neuroscience"; Top-down suppression deficit underlies working memory impairment in normal aging; Gazzaley, et al.; September 2005
- "Journal of Abnormal Psychology"; Neurological correlates of reward responding in adolescents with and without externalizing behavior disorders; Gatzke-Kopp, et al.; March 2009
