Over the holidays, I got together with a group of women who I've been friends with since our children were babies. Now that our kids are in their tweens and teens, our conversations are no longer dominated by talk of sleep schedules, diaper changes and cures for colic. Increasingly, our concerns seem to be finding a different focus. I was struck by the fact that every single one of us had at least one parent or parent-in-law who is dealing with some form of dementia. And for as much as I've written about mental health, I realized that I didn't fully understand the differences between Alzheimer's disease and other forms of mental confusion.

So I did a little digging, and here's what I found out.

Essentially, Alzheimer's disease is a form of dementia. Dementia, in and of itself is not a disease but rather an umbrella term used to describe a general loss of mental abilities and memory. It can be caused by many things, including Alzheimer's.

Alzheimer's is the most common type of dementia, accounting for 60 to 80 percent of cases. It's a progressive disease marked by memory loss, confusion and disorientation. The symptoms usually start off as minor — forgetting names or dates or other newly learned information. But over time, symptoms can include behavior changes, difficulty speaking and impaired movement. While the risks for developing Alzheimer's disease increase with age, it's not an unavoidable complication of aging.

Tons of research has been compiled in recent years in an effort to understand what triggers the brain changes that cause Alzheimer's disease. Plaque deposits and twisted fibers known as tangles can be seen in brain scans as the disease progresses. But at the moment the cause of Alzheimer's remains a mystery.

Other diseases that can lead to the development of dementia include vascular dementia (which may occur as a complication from a stroke,) Parkinson's disease and Huntington's disease.

Bottom line: If a parent or loved one is beginning to show signs of dementia, it's important to get them in for a check-up. While there is no known cure for Alzheimer's disease and other forms of dementia, there are treatments that can delay the progression of symptoms.