Lack of Sleep

First, it's harder to recall things when you haven't slept. Second, sleep strengthens the bonds between brain cells that help you remember for the long term. Third, it's harder to form memories in the first place when your mind is wandering because of a lack of sleep. Good "sleep hygiene" can help: Shoot for 8 hours a night, exercise daily, stick to a regular sleep schedule, and avoid alcohol and caffeine late in the day.

Medication

Drugs that sedate you, like sleep aids and tranquilizers, can weaken your memory, as you might imagine. But so can less obvious culprits, like blood pressure meds, antihistamines, and antidepressants. Plus, you may react differently than someone else to the same pill or combination of pills. Tell your doctor about any memory issues when you start a new medication. They may be able to adjust the dose or prescribe an alternative.

Diabetes

People with the disease are more likely to develop memory problems including dementia. It may be that high blood sugar damages tiny blood vessels called capillaries in the brain. Or it may be that high insulin damages brain cells. Scientists continue to study the issue. You might be able to slow this memory decline if you try to prevent or at least control your diabetes with medicine, exercise, and a healthy diet.

Genes

Genes - traits you got from your parents - help determine when and if your memory starts to fade and whether you get dementia. But it's not simple. Genetics seem to matter more in some types of dementia than others, and a gene that affects memory in one person might have no effect in another. A genetic test from your doctor might have some useful information.

Age

Memory tends to get worse as you get older. Doctors call it dementia when it starts to interfere with daily life. The number of people with Alzheimer's, the most common form of dementia, doubles every 5 years after age 65. Your genes play a part in why this happens, but so do things like diet, exercise, social life, and illness like diabetes, high blood pressure, and heart disease.

Stroke

A stroke stops the flow of blood to part of your brain. Afterward, damaged brain tissue can make it hard to think, speak, remember, or pay attention. It's called vascular dementia. This can also happen with a series of small strokes over time. Things that raise your risk of stroke like high blood pressure, heart disease, and smoking may also cause this type of dementia. If you think you're having a stroke, remember FAST: Face drooping, Arm weakness, Speech problems, Time to call 911.

Smoking

Smoking seems to shrink parts of your brain that help you think and remember things. It also raises your risk of dementia, possibly because it's bad for your blood vessels. And it definitely raises your risk of stroke, which can damage the brain and cause vascular dementia. Talk to your doctor or a mental health professional if you smoke and want to quit.

Heart Disease

Plaque builds up in your arteries and slows blood flow to your brain and other organs. This is called atherosclerosis. It can make it harder to think clearly and remember things. It also could lead to a heart attack or stroke, which both also raise your chances of dementia. And even if you don't yet have heart disease, possible causes - smoking, diabetes, high blood pressure - make dementia more likely.

High Blood Pressure

Also called hypertension, it raises your risk of memory problems, including dementia, most likely because it damages the tiny blood vessels in your brain. It also can lead to other conditions like stroke that cause dementia. People who control their blood pressure with diet, exercise, and medication seem to be able to slow or prevent this brain decline.

Depression and Anxiety

It's often harder to concentrate or recall things if you're anxious or depressed. Plus, you're also more likely to develop dementia, though scientists don't yet know exactly why that happens. Talk to your doctor or therapist if anxiety or depression interfere with your enjoyment of normal daily life or you think of harming yourself. Therapy and medication can help.

Head Injury

A hit to the head (traumatic brain injury) can affect short-term memory. You might forget appointments or feel unsure of what you did earlier in the day. Rest, medicine, and medical rehab can help you recover. Repeated hits to your noggin, as in boxing or football, raises your risk for dementia later in life. Get to the hospital if you hit your head and then pass out or have blurry vision, or if you feel dizzy, confused, or nauseous.

Obesity

If your body mass index (BMI) is over 30 in middle age, you have a higher risk for dementia later in life. And extra pounds anytime make heart disease more likely, which also sometimes leads to brain decline and memory problems. You can calculate BMI online with your height and weight. Talk to your doctor about the right weight for you. You may be able to improve yours with a healthy diet and regular exercise.

Lack of Exercise

Regular exercise lessens the risk of brain decline, memory problems, and dementia. It also seems to improve brain function in those who already have dementia. You don't have to go out and run a marathon or take up pole vaulting. Just get out and garden, walk, swim, or even dance for 30 minutes on most days of the week.

Bad Diet

Unhealthy eating can lead to heart disease, which can cause brain issues including memory problems and dementia. That's why the heart-healthy Mediterranean-style diet is good for your brain, too. It stresses whole grains, fruits, vegetables, fish, nuts, olive oil, and other healthy fats like avocado, and keeps the red meat to a minimum.