People who are experiencing symptoms of cognitive decline should seek a diagnosis. An early diagnosis can make a difference, since it can cause someone to make lifestyle changes and/or start a treatment that can help them maintain or even improve their cognitive abilities. However, Dr. Marwan Sabbagh, a board-certified behavioral neurologist at Barrow Neurological Institute’s Alzheimer’s and Memory Disorders Program and a professor at the institute’s Department of Neurology, has said that dementias are difficult to diagnose and, as a result, misdiagnoses are common.

MCI, or Mild Cognitive Impairment, refers to cognitive impairment without functional impairment. It is possible to have an MCI diagnosis with Parkinson’s, Lewy Body disease, etc. One of the main distinctions between MCI and Alzheimer’s is that people with MCI have more difficulty with memory than their peers, but are still able to live independently and carry out their normal daily activities.

Brain changes associated with Alzheimer’s include the presence of proteins called beta amyloid and tau. Beta-amyloid clumps into plaques, which slowly build up between brain cells, while abnormal tau accumulates inside brain cells, forming tangles. These changes can lead to a progressive decline in memory and thinking skills. Up until recently, doctors mainly used a PET scan of the brain, or a lumbar puncture to test cerebrospinal fluid, to reveal disease-related changes (pathology). These changes can appear twenty years before the onset of symptoms. 

A PET scan is very expensive and involves radioactive agents, while a lumbar puncture can be invasive. As a result, it has been difficult for primary care doctors to identify Alzheimer’s disease, even among patients with cognitive impairment. This sometimes leads to diagnostic uncertainty and inappropriate treatment.

In July, the first direct-to-consumer blood test designed to assess a user’s risk for developing Alzheimer’s disease hit the market. The test, which has not undergone Food and Drug Administration (FDA) review, measures the level of beta amyloid. It is recommended that this blood test be reserved for people who are at risk or are having early symptoms of memory issues. 

This simple, finger prick blood test – not so different from what people with diabetes do every day – shows promise in the ability to detect Alzheimer’s disease, according to research reported for the first time at the Alzheimer’s Association International Conference^® (AAIC^®) 2023, in Amsterdam, Netherlands, and online. Such a blood test may help rule out other potential causes of memory loss and confusion, such as a thyroid disorder or vitamin levels that are too low. Blood tests for Alzheimer’s disease have promise for improving diagnostic accuracy and proper treatment of people with Alzheimer’s. The use of this type of blood test would also enable doctors to rapidly screen a much larger and more diverse group of volunteers who wish to enroll in studies.