It's well-known that exercising to maintain a healthy heart also helps create a healthy mind. But several new studies suggest that when it comes to preventing dementia, not all forms of exercise are created equal.

Studies presented at this year's Alzheimer's Association International Conference found that resistance training was particularly beneficial for improving the cognitive abilities of older adults.

While the studies were small, all including 150 participants or less, they did seemed to indicate that resistance training -- such as weight lifting or using resistance bands -- could possibly be an intervention for dementia in older adults.

One study divided a group of 86 women, all between the ages of 70 and 80, into three different exercise groups: Weight lifting, walking, or balance and tone exercises. Each group did the exercises twice a week for 6 months.

Everyone appeared to benefit from the exercise.

"We actually imaged their brains, using functional MRIs -- and these people showed better brain function," explained lead investigator, Dr. Teresa Liu Ambrose.

Participants were tested for cognitive executive functions such as attention, memory and planning. According to Ambrose, "the cognitive executive function and associated memory -- those are the two traits most linked to dementia."

At the end of the trial, those in the weight lifting group were most improved.

Ambrose, who is the director of the Aging, Mobility, and Cognitive Neuroscience lab at the University of British Columbia, tells CNN: "We accept that exercise is the golden bullet -- but we need to identify who might benefit the most from what exercise."

"It's definitely one of the first times resistance training has been looked at in connection with Alzheimer's. And we've seen in that body of literature that people who do resistance training increase their ability to be more mobile, but it may have some other benefits," said Heather Snyder of the Alzheimer's Association.

What was also striking was that those who started with a higher cognitive baseline actually gained the most benefits from exercise.

Ambrose led another study that followed 155 women, aged 65 to 75, over the course of a year, who did either strength training or balance and toning exercises.

"You would think if you had more impairment, you would have more improvement, but this says the opposite. This highlights that resistance training improves cognition, but you really have to consider a person's cognitive abilities," said Ambrose.

According to the Alzheimer's Association, 5.4 million Americans are living with Alzheimer's today. It's the sixth leading cause of death in the U.S. By 2050, that number of people with Alzheimer's in the United States is expected to nearly triple to 16 million. The cost of caring for all those people is estimated to top $1 trillion dollars each year.

Which is why early detection is so key.

Several studies released at the convention pointed to the effectiveness of gait measurement as a predictor for dementia.

Falling has already been identified as one of the early indicator's of Alzheimer's, but several new studies show that how we walk may also be an early sign for a decline in cognitive function.

Three studies, presented at the conference, surveyed more than 1,000 people each -- the largest of their kind -- and all found that slower and irregular gait was associated with some cognitive impairment.

But many researchers, including neurologist, Dr. Lisa Silbert, of the Oregon Health and Science University in Portland, Oregon, warned it wasn't a diagnosis.

"Some degree of motor slowing is also likely a part of the aging process."