When it comes to preserving memories, we are sometimes our own worst enemies. The lives we lead often undermine the complex process of creating and retrieving memories. And they can boost the odds of our developing diseases -- including Alzheimer's -- that further ravage the brain's mechanisms of memory. Here are things that science tells us pose the greatest threat to our memories: Knowing them, says UCLA neurologist Dr. Gary Small, may allow us "to act early to prevent."
Many medications prescribed widely in the U.S. can cause memory problems. Among the most likely to disrupt memory are benzodiazepines (including Ativan, Valium and Xanax). Any drug that can cause drowsiness can disturb concentration and absorption of new facts -- there are legions of those, including over-the-counter antihistamines.
Some drugs have been discovered by accident to have memory-disrupting qualities and have been hailed as possible treatments for those at risk of post-traumatic stress disorder. Beta blockers, prescribed widely, have been shown to reduce the emotional power of certain memories and are being investigated by the U.S. military. Propofol, a sedative colloquially known as "milk of amnesia," can also erase a few minutes of memory.
Untreated heart disease
High blood pressure, high cholesterol, Type 2 diabetes and obesity all raise the risk of stroke, which can affect memory profoundly. Studies have also found those with Type 2 diabetes at three times greater risk for Alzheimer's as the general population. Those with high cholesterol and blood pressure in midlife are also at greater risk. And obesity (particularly excess fat around the middle) has been linked to higher dementia rates 30 years later.
Researchers know that high emotion surrounding an event assures that it will be committed to memory. As the brain floods with adrenaline and norepinephrine, the mechanisms of memory are excited. Episodes of high stress, intense happiness, love and sadness can preserve a sharp memory. But when stress is constant and the brain is bathed chronically in stress hormones such as cortisol, attention grows weak and events are stored fitfully in short-term memory and fitfully committed to long-term memory. Established memories are poorly retrieved.
Cortisol overload will cause many of the brain cells with memory functions to power down. And over time, chronic stress will degrade communications between cells in brain regions important to learning and memory. Even several hours of steady stress can flood the brain with hormones that disrupt memory, according to a March report by UC Irvine researchers in the Journal of Neuroscience.
Alcoholism causes progressive brain shrinkage and disrupts communications between regions involved in storing and retrieving memories. In the extreme, an alcoholic can exhibit total loss of long-term memories. But memory "blackouts" and fragmented recollection are common even among social drinkers, researchers have found. Heavy alcohol use can also cause vitamin B1 deficiencies, which along with vitamin B12 deficiencies can negatively affect memory.
It sabotages concentration and with it, memory. Brain-imaging reveals that depression decreases activity in the brain's frontal lobes, a linchpin of memory-making.
A study reported in 2006 by University of Rochester researcher Mark Mapstone found that among middle-aged women, those with depressive symptoms had more complaints of memory lapses and poorer performance registering new information than those without mood disturbance.
Mapstone found that the women did not show cognitive problems on neuropsychological tests. With their attention spread thin by competing demands and mood disturbances affecting concentration, many fear they have Alzheimer's when in fact they may have problems getting information into the memory stream, rather than storing or retrieving it. Attention-deficit disorder and sleep deprivation are thought to have similar effects.
Couch potato lifestyle
Physical and mental exercises are essential to keeping memory functioning: Lack of either is associated with memory problems, especially as we age.
The brain, like any organ, benefits from improved blood flow that comes with aerobic activity. And its tissues are strengthened with increased use. Plus, studies show that those with higher education levels and a habit of mental stimulation build up a "cognitive reserve" that reduces the symptom severity even when their brains are under attack by Alzheimer's. "It's a common sense expression, but it seems to be true: A huge amount of data says use it or lose it," says UC Irvine neuroscientist James McGaugh.