This form of dementia is actually a conglomeration of 3 different subtypes of dementia. They all share a common mechanism which is the abnormal proliferation of the tau protein within the neurons leading to ultimate demise of the neuron. For unclear reasons, the disease starts either in the frontal or temporal lobes before involving other parts of the brain. Each of the 3 subtypes has a unique set of early symptoms. Sometimes it is a change in behavior with exaggeration of underlying personality traits. Other times it presents with difficulty creating speech. Eventually the three subtypes progress to be difficult to distinguish during the later stages of the dementia.