
Stress hormones may be to blame, triggering harmful alterations in the brain. These can cause a number of changes in the body and affect things such as blood pressure and blood sugar control.
However, more work is needed to confirm the findings and ascertain whether the same stress and dementia link might also occur in men. See more here. http://www.bbc.co.uk/news/health-24332082
But what is stress? Pressure turns into stress when you feel unable to cope. People have different ways of reacting to stress, so a situation that feels stressful to one person may be motivating to someone else.

You may feel anxious, irritable or low in self esteem. You may have racing thoughts, worry constantly or go over problems. Perhaps you lose your temper more easily, drink more, act unreasonably or even experience headaches, muscle tension or pain, or dizziness.
Stress causes a surge of hormones in your body. These stress hormones are released to enable you to deal with pressures or threats – the so-called "fight or flight" response to rouse the body for emergency action.
Your heart pounds faster, blood pressure rises, breath quickens, muscles tighten, and your senses become sharper. These physical changes increase your strength and stamina, speed your reaction time, and enhance your focus.
Once the pressure or threat has passed, your stress hormone levels will usually return to normal. However, if you're constantly under stress, these hormones will remain in your body, leading to the symptoms of stress and can proceed to dementia according to the new report.

The stress response also helps you rise to meet challenges. Stress is what keeps you on your toes during a presentation, sharpens your concentration when you’re attempting to answer a question ahead of your peers, or the game-winning maneuver in sports. Stress drives you to study for an exam when you'd rather be watching TV.
But beyond a certain point, stress stops being helpful and starts causing major damage to your health, your mood, your productivity, your relationships, and your quality of life. A helpful site on dealing with stress. http://www.helpguide.org/mental/stress_signs.htm
When I split with my first husband over 25 years ago, I suffered quietly. After moving closer to my mother, the doctor diagnosed clinical depression and suggested I find a job that would lift me out of the cycle. I worked as a companion for about six months, and then as a nanny, eventually moving from Australia to London in that capacity. I've never reached that low point since. I'm hoping those stressful times didn't damage my brain. Maybe a positive attitude can combat a potential threat.