Dementia is an umbrella term for a group of symptoms, like memory loss, confusion and difficulty with language, that affect daily life. Alzheimer's disease is the most common type of dementia, accounting for 50% to 70% of all cases. 

In other words, Alzheimer’s is a type of dementia, but not all dementia is caused by Alzheimer's disease.

Early signs are usually mild, starting with simple forgetfulness that can be mistaken for normal aging. As dementia progresses, you may have symptoms related to:

• Memory: Forgetting recent events, names or familiar places
• Speech: Trouble finding words or following conversations
• Judgment: Making unusual decisions or losing track of finances
• Concentration: Trouble focusing or completing familiar tasks

Alzheimer’s has several different symptoms, which include:

• Difficulty completing daily, familiar tasks
• Being confused or irritable
• Memory loss
• Problems with cognition
• Trouble with speech or writing
• Difficulty problem-solving
• Mood and personality changes

These signs don’t always mean you have Alzheimer’s disease, but it’s worth talking to your doctor about getting a proper diagnosis.

There are several types of dementia, each with different causes and symptoms. Alzheimer's is the most common, but other types include: 

• Vascular dementia: This condition is caused by a lack of blood flow to the brain and is thought to be related to strokes or hardening of the arteries. Symptoms include confusion, difficulty completing tasks, inability to concentrate for long stretches and changes in how you walk.
• Dementia with Lewy bodies (DLB): A progressive form that can cause changes in behavior, such as visual hallucinations or other visual disturbances, sleep disturbance, trouble with concentration and planning, fainting, and difficulty with movement such as slowness, stiffness, tremors and imbalance.
• Parkinson’s disease with dementia (PDD): This form has similar symptoms to dementia with Lewy bodies, but dementia develops after movement symptoms such as tremors and stiffness.  
• Mixed dementia: This means more than one type of underlying disease is causing dementia. Symptoms can vary depending on the types of dementia.
• Normal pressure hydrocephalus (NPH): This condition involves the buildup of excess fluid in the brain’s ventricles (fluid-filled spaces). NPH causes difficulty with balance, thinking and memory, and urinary incontinence.
• Frontotemporal dementia (FTD), or Pick’s disease: This type of dementia may run in families and can affect people as young as 45. Symptoms can include changes in behavior and personality (e.g. loss of filter, eating habits, loss of sympathy and empathy) and speech and language (loss of word meanings).
• Wernicke-Korsakoff syndrome (WKS) and Wernicke’s encephalopathy: WKS affects the ability to retain and process information and can mimic Alzheimer’s. It can be caused by vitamin B1 deficiency, which may be brought on by alcohol misuse or general malnutrition.

To confirm a dementia or Alzheimer’s diagnosis and rule out other causes of memory loss, your doctor will typically perform:

• Detailed history review: gathering signs and symptoms from patients and caregivers or loved ones.
• Physical, neurological and cognitive screening exams: These tests assess reflexes, muscle tone and strength, coordination, balance, vision, hearing and range of motion, as well as higher brain function via pen-and-paper testing.
• Blood tests: These help rule out other possible causes of memory loss and can also test for markers of Alzheimer’s in the blood.
• Magnetic resonance imaging (MRI): Using powerful radio waves and magnets, an MRI creates detailed images of the brain that can reveal structural abnormalities that can be seen in dementia.
• Computerized tomography (CT): A CT scan uses radiation to create a detailed image of the brain.
• Electroencephalogram (EEG): This test measures electrical activity in the brain.
• Cerebrospinal fluid (CSF) test: This test can find Alzheimer’s disease proteins and may rule out other causes of memory loss.
• Positron emission tomography (PET): Rather than show the brain's structure, like MRIs and CT scans, a PET scan reveals the brain’s activity and how areas of the brain work to metabolize nutrients. When coupled with a specific radioisotope, such as in an amyloid PET scan, it can diagnose Alzheimer’s.
• Dopamine Transporter Reupdate scan (DaTscan): This imaging test helps diagnose Parkinson’s disease and other disorders like Lewy body disease.