Reversible Dementia Causes vs Irreversible Dementia Causes. Dementia stems from a variety of causes, some of which are treatable and others that are not. Treatments for reversible dementia causes are intended to slow the progress of the dementia, and in some cases, may be able to reverse some symptoms.If the underlying cause of dementia is irreversible, doctors will treat the symptoms of the condition with the hopes of making life as easy as possible for the individual.Here are a few examples of different causes of dementia: This happens when an outside force hits the skull and causes damage to the brain.head injuries are often the result of an auto accident or a fall, and any subsequent decline in cognition is categorized as dementia.ere are a few examples of different causes of dementia: This happens when an outside force hits the skull and causes damage to the brain. head injuries are often the result of an auto accident or a fall, and any subsequent decline in cognition is categorized as dementia.