Unlikely. Although you have an increased chance of developing Alzheimer's because you have a first degree relatives suffering from dementia, this is only slightly increased. Over 95% of Alzheimer's cases are idiopathic, with no known cause. If you're father developed Alzheimer's disease in his 40s or 50s, this would be known as an early-onset form , which is typically a familial inherited form of the disease caused by a genetic mutation in either the APP or PS1 genes. If your father is suffering from the typical late-onset form of Alzheimer's disease, which is usually found in patients 65 years of age or older, you have a only a slightly greater risk of developing this disorder, compared to the regular population.