New Research Illuminates Memory Loss and Early Dementia

New Research Illuminates Memory Loss and Early Dementia



"Where are my glasses?" "Remind me who that person is. I can't remember his name." "What's the word I'm looking for? It's right on the tip of my tongue."

Sound familiar? As people get older, they often have "senior moments," episodes of minor forgetfulness that can be frustrating. Are these moments part of healthy aging or the first sign of something more serious, like Alzheimer's disease (AD)?

"Recent research has greatly enhanced our understanding of how memories are formed and what really happens in the brain when memory loss occurs," says Dr. Marcelle Morrison-Bogorad, director of the NIA's Division of Neuroscience. "These findings are helping us focus on the very earliest stages, when normal aging may be giving way to a disease process such as AD. Knowing more about these early events will help us understand what may trigger the AD process and will contribute to improved diagnosis and effective treatments."

Is it forgetfulness or a memory disorder?

Studies have shown that the aging brain is much more adaptable than once thought. For example, as adults age, they improve in some cognitive areas, such as vocabulary and other forms of verbal knowledge. The brain also continues to develop new neurons (nerve cells) in certain regions, even late in life. Pathways used by neurons to transmit signals can reroute themselves to bypass obstructions and maintain essential communications.

However, studies of memory and cognition have found that healthy people also may lose some cognitive function as they get older. They may have more difficulty learning new information, remembering things, or doing tasks like planning or making decisions.

These minor declines in memory and cognitive ability may occur because the brain, like other parts of the body, changes with age:

•Certain parts of the brain that are important in learning, memory, planning, and other complex cognitive activities shrink with age.
•The ability of neurons in certain brain regions to communicate efficiently with each other declines.
•Blood flow in the brain is reduced because arteries narrow and fewer new capillaries grow.
•Plaques and tangles develop first outside of neurons and then within neurons, although in much smaller amounts than in AD. Plaques are abnormal clumps of proteins and other fragments that may block communication between neurons. Tangles are changes in a brain protein called tau that may cause important microtubules to become twisted and disintegrate. These microtubules transport cellular materials down the neurites, which are extensions from neurons that connect one neuron to another.
•Damage by free radicals increases. (Free radicals are very unstable molecules; a buildup of these molecules can damage important components of cells.)
•Inflammation in the brain increases. (Inflammation is a complex process that occurs when the body responds to an injury, disease, or another abnormal situation.)
For some people, the brain changes that come with age are minimal and result in occasional memory lapses, such as forgetting keys or blanking out on a person's name. Others experience progressive and significant declines in their ability to remember things, without having other problems characteristic of AD, such as difficulty processing and organizing information, problems with judgment and decision-making, personality changes, and psychiatric and behavioral problems.

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Alzheimer's Disease Education and Referral Center
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