Symptoms of dementia vary greatly depending on the cause, but patients generally experience cognitive and psychological changes, according to Mayo Clinic. Cognitive changes include disorientation, difficulty performing complex tasks, coordination issues and communication problems. People with dementia might also experience paranoia, an inability to reason, agitation and hallucinations.
At least two of the following primary brain functions need to be disabled for a patient to be diagnosed with dementia: communication and language, reasoning and judgment, memory, visual perception and the ability to focus, according to the Alzheimer's Association.
The affected area of the brain can also influence the symptoms that a patient experiences, reports WebMD. The earliest symptom tends to be memory loss, although brief memory problems tend to be a normal part of the aging process. Some subtypes of dementia can cause specific symptoms, such as frontotemporal dementia, which causes extremely unusual behavior changes, and Lewy body dementia, which causes detailed visual hallucinations.
Other early warning signs of dementia include apathy, repetition and difficulty adapting to changes, notes Healthline. An elderly person who suddenly becomes listless and loses interest in spending time with loved ones might be experiencing early stages of dementia. People going through these early stages may also begin to obsessively stick to routines when they forget people they should know and have difficulty following conversations.