Common symptoms of dementia vary greatly among sufferers; however, patients are diagnosed with dementia if they experience a decline or impairment of at least two of the five following mental functions: language, memory, judgment, the ability to focus and visual perception, according to the Alzheimer's Association. Alzheimer's disease is the most common kind of dementia, and patients often struggle with their short-term memory, forgetting daily tasks such as preparing meals, paying bills and remembering obligations.
Several types of dementia begin with symptoms that appear slowly but gradually become worse, reports the Alzheimer's Association. Between 60 and 80 percent of dementia sufferers have Alzheimer's disease, and early symptoms and signs of the latter condition include memory loss that disrupts a patient's daily tasks and problems doing familiar routines at work or at home. Patients with Alzheimer's disease also often encounter challenges with comprehending visual images, following recipes, solving number problems and focusing on plans. Elderly people who constantly lose their sense of time or place and isolate themselves from work interactions and social gatherings can be suffering from early symptoms of Alzheimer's disease as well.
Patients with dementia often struggle with controlling their behaviors or moods, make bad judgment calls and fail to maintain basic personal hygiene and care, according to WebMD. Those who have dementia with Lewy bodies fall down often and have vivid visual hallucinations.