Dementia is not a single disease. It is a general term for a decline in cognitive ability severe enough to interfere with daily life. Alzheimer's disease is the most common cause, accounting for 60 to 80 percent of cases, but vascular dementia, Lewy body dementia, frontotemporal dementia, and mixed forms also occur. The condition primarily affects older adults, though early-onset forms can appear before age 65.

The symptoms of dementia vary depending on the cause and the parts of the brain affected, but common early signs include:

• Memory loss that disrupts daily life. Forgetting recently learned information, important dates, or events. Asking the same questions repeatedly.
• Difficulty planning or solving problems. Trouble following a familiar recipe, managing bills, or concentrating on tasks that require sequential steps.
• Confusion with time or place. Losing track of dates, seasons, or the passage of time. Getting lost in a familiar location.
• Language problems. Struggling to follow or join a conversation, stopping mid-sentence without knowing how to continue, or using incorrect words for common objects.
• Impaired judgment. Making poor decisions about money, personal safety, or hygiene.
• Withdrawal from activities. Pulling away from hobbies, social engagements, or work projects.
• Changes in mood and personality. Becoming confused, suspicious, depressed, fearful, or anxious. Being easily upset in situations that previously caused no distress.

It is normal to occasionally forget where you put your keys or blank on an acquaintance's name. The difference with dementia is that these lapses become more frequent, more severe, and begin to affect the ability to function independently.

Diagnosing dementia involves a thorough medical evaluation. No single test can determine whether a person has the condition. A physician will typically review the individual's medical history, conduct a physical examination, order laboratory tests, and assess cognitive function through standardized neuropsychological testing. Brain imaging, such as CT or MRI scans, may be used to identify structural changes, strokes, or tumors that could be contributing to symptoms.

The diagnostic criteria in the DSM-5 describe dementia under the broader category of Major Neurocognitive Disorder. A diagnosis requires evidence of significant cognitive decline from a previous level of performance in one or more cognitive domains (learning and memory, language, executive function, complex attention, perceptual-motor function, or social cognition), and these deficits must interfere with independence in everyday activities.

While there is currently no cure for most forms of dementia, early diagnosis remains valuable. It allows individuals and their families to plan ahead, access support services, address reversible contributing factors, and participate in clinical trials. Non-pharmacological approaches that have shown benefit include cognitive stimulation therapy, physical exercise programs, occupational therapy, music and art therapy, and structured daily routines. Caregiver education and support groups also play a significant role in managing the condition.

Some conditions that mimic dementia are treatable. Depression, urinary tract infections, vitamin B12 deficiency, thyroid dysfunction, and normal pressure hydrocephalus can all produce dementia-like symptoms and may improve with proper care. This is one of the most important reasons to seek professional evaluation rather than assume the worst.

If you or someone you care about is experiencing persistent changes in memory, thinking, behavior, or the ability to perform everyday tasks, it is time to see a doctor. Many people delay seeking evaluation because they attribute these changes to normal aging or because they fear the diagnosis. But early assessment offers real benefits regardless of the outcome.

You should seek medical attention promptly if:

• Memory problems are getting worse over weeks or months rather than staying stable.
• Confusion or disorientation occurs in familiar settings.
• There are noticeable personality or mood changes that friends and family have remarked upon.
• Routine tasks like cooking, driving, or managing finances have become significantly harder.
• Safety concerns have arisen, such as leaving the stove on, getting lost while driving, or falling for scams.

Start by speaking with a primary care physician. They can perform an initial screening and, if needed, refer you to a neurologist or a memory disorders clinic for specialized testing. Bringing a close family member or friend to the appointment is helpful, as they can provide an outside perspective on changes they have observed.

For reliable information and support, the following resources may be helpful:

• Alzheimer's Association: What Is Dementia?
• National Institute on Aging: Alzheimer's and Dementia Resources
• NHS: Dementia Overview

This online screening is not a substitute for a professional clinical assessment. It is designed to help you identify symptoms that may require further evaluation. Whatever your results, if you are worried, that concern is valid, and a qualified healthcare provider can help you understand what is happening.