While signs and symptoms of dementia vary, a person suffering from the condition experiences an impairment of at least two of the following main mental functions: communication, reasoning, memory, visual perception and the ability to pay attention, according to the Alzheimer's Association. Many forms of dementia start out with subtle signs but gradually worsen. Patients with dementia often have short-term memory issues and forget routines, such as paying bills, remembering appointments or planning meals.
The most common form of dementia is Alzheimer's disease, explains the Alzheimer's Association. Some early warning signs of Alzheimer's include a form of memory loss that disrupts a person's daily activities; issues with following plans or solving problems; difficulties with completing regular tasks or habits; losing track of time or place; and problems with understanding spatial relationships. While memory loss is a common symptom of dementia, it can often be an age-related change, especially if the patient eventually remembers what he forgot earlier. Other early signs of Alzheimer's include misplacing objects, having trouble speaking or writing, using poor judgment skills, experiencing mood swings, and withdrawing from social activities.
People suffering from frontotemporal dementia exhibit unusual behavior and abrupt personality changes, states WebMD. People who have dementia with Lewy bodies often trip frequently and have highly detailed visual hallucinations. When dementia symptoms suddenly manifest, this can be due to delirium or vascular dementia.