Question: Are their any external influences (of which living in the modern day and age present) known to have an effect on the rate of which alzheimer's develops or is it just a natural occurance that develops with old age?

Good question, diet and exercise are very important, so the increase in people eating fatty, sugary foods and not exercising enough puts you at higher risk of getting Alzheimer’s.
But, the number one biggest risk factor is age, the longer you live for, the more likely it is that you will develop Alzheimer’s. We don’t know exactly why yet, but it may have to do with a build up of toxic poisons in the brain.