Inappropriate language or behaviour typically occurs in moderate Alzheimer's diseaseAlzheimer's disease A neurological disease that affects memory and behaviour. It is characterized by beta-amyloid plaques and neurofibrillary tangles in the brain. There is no known cause but genetics and lifestyle are thought to play a role.. In frontotemporal dementiaFrontotemporal dementia A type of dementia that mainly affects the frontal lobe causing a problem in executive function tasks., this can be an early signSign In medicine a sign is what a physician finds by examining a patient. For example, a patient with the symptom of pain might have signs of a fast heart rate, a pale face, a clammy touch and tenderness. of the disease.