Cognitive Impairment Symptoms Can Vary

A diagnosis of cognitive impairment can be disorienting and devastating, not only for the patient but for friends and family. Unfortunately, it is also becoming increasingly more common.

Alzheimer’s is perhaps the best-known and most common dementia diagnosis in the United States. However, others are also growing, each with unique characteristics. Among them are vascular dementia, Lewy body dementia, and frontotemporal dementia.

Alzheimer’s Disease

According to the Centers for Disease Control, Alzheimer’s is the most common cause of dementia, accounting for 60 to 80 percent of cases. [1] An estimated 6 million Americans are currently living with Alzheimer’s. [2]

Common symptoms include [2]:

  • Memory loss, especially of recent names, places, and new information
    • Confusion about time and place
    • Struggling to complete familiar tasks
    • Trouble finding the appropriate word
    • Difficulty in judgment
    • Changes in mood and personality

Alzheimer’s is a progressive brain disease, and the risk of diagnosis increases after age 65, with about one-third of people older than 85 estimated to have the condition. In addition to aging, health, environmental, and lifestyle factors may contribute to the risk of developing the disease. [3] Alzheimer’s is characterized by abnormal accumulations of proteins that can form plaque around brain cells, which twist strands of protein within the brain, according to Riordan Clinic Chief Medical Officer Dr. Ron Hunninghake, MD.

Vascular Dementia

This form of dementia is a common type of dementia, and symptoms often overlap with those of Alzheimer’s and other types of dementia. Unlike Alzheimer’s, the most significant symptoms include slowed thinking and problem-solving instead of memory loss. Cognitive problems in vascular dementia are often caused by brain damage from impaired blood flow to the brain. Patients can develop vascular dementia after a stroke blocks an artery, but strokes don’t always cause vascular dementia. Other conditions that deprive the brain of oxygen and nutrients can also cause the disease. [4]

Common symptoms include [4]:

  • Reduced ability to organize thoughts or actions
    • Slowed thinking
    • Difficulty with organization
    • Difficulty paying attention or concentrating
    • Difficulty analyzing a situation, developing an action plan, and communicating it to others

Risk factors for vascular dementia include a history of strokes or mini-strokes. Unlike the usual gradual progression of Alzheimer’s, symptoms may occur suddenly after a stroke or series of mini-strokes. However, they can occur gradually as well. Other risk factors include age, high blood pressure, diabetes, smoking, obesity, and a build-up of plaque and cholesterol in the arteries, which reduces blood flow to the brain. [4]

Lewy Body Dementia

Lewy body dementia is another common type of progressive dementia. Unlike Alzheimer’s, patients can also experience Parkinson’s disease symptoms. This can include difficulty with movement and regulation of body functions related to the nervous system, as well as spontaneous changes in attention and alertness, recurrent hallucinations, and sleep disorders. This type of dementia may be linked to underlying abnormalities in how the brain processes the protein alpha-synuclein, which neurologist Dr. Frederich H. Lewy discovered in the early 1900s. [5]

Common symptoms include [6]:

  • Movement problems, such as rigid muscles, tremors, or stiff walking
    • Hallucinations
    • Fluctuating attention, such as episodes of drowsiness, staring into space, long daytime naps, or disorganized speech
    • Depression
    • Apathy
    • Cognitive problems such as confusion, poor concentration, visual-spatial problems, and memory loss

Risk factors for Lewy body dementia aren’t well known. The greatest risk factor is age, although the disease can have a younger onset than Alzheimer’s, with most disease diagnosed in individuals age 50 and older. Rapid Eye Movement Sleep Behavior Disorder is considered another risk factor for this type of dementia. This sleep disorder is characterized by dream enactment and can occur many years before the onset of Parkinson-like symptoms or cognitive impairment. [7]

Mixed Dementia

In addition to singular causes of dementia, many patients also have brain changes linked to two or more types of cognitive disease. Common combinations include Alzheimer’s and vascular dementia and Alzheimer’s and Lewy body dementia. A study funded by the National Institute on Aging (NIA) showed that more than 50 percent of the volunteers in the study whose brains met the criteria for Alzheimer’s also had evidence of one or more additional dementias. The NIA study showed that the majority of those found to have multiple dementias were only diagnosed with Alzheimer’s during their lifetime. Autopsies of those individuals revealed co-existing dementia. [8]

Mild Cognitive Impairment

Mild Cognitive Impairment (MCI) is age-related brain changes that do not significantly impact daily life or affect usual activities. While it may progress to dementia, some patients never advance to that point. Studies show that approximately 10-15 percent of people with MCI will develop dementia each year. [9]


While there is no one-size-fits-all dementia diagnosis, Alzheimer’s is the most common cognitive disease in the United States. However, symptoms vary to differentiate the types of dementia commonly seen in patients and, at times, overlap to create mixed dementia. The Alzheimer’s Association is a resource not only for Alzheimer’s but also for other types of dementia. Access descriptions online at


  1. Centers for Disease Control and Prevention. (2019, April 5). What is dementia? Centers for Disease Control and Prevention. Retrieved March 16, 2023, from
  2. About Alzheimer’s disease and dementia. Alzheimer’s Foundation of America. (2022, April 14). Retrieved March 16, 2023, from
  3. U.S. Department of Health and Human Services. (n.d.). What causes Alzheimer’s disease? National Institute on Aging. Retrieved March 16, 2023, from,differ%20from%20person%20to%20person
  4. Mayo Foundation for Medical Education and Research. (2021, July 29). Vascular dementia. Mayo Clinic. Retrieved March 16, 2023, from,solving%20rather%20than%20memory%20loss
  5. Dementia with Lewy bodies (DLB): What is it and what causes it? Alzheimer’s Society. (2018, June 8). Retrieved March 16, 2023, from
  6. Mayo Foundation for Medical Education and Research. (2021, June 8). Lewy body dementia. Mayo Clinic. Retrieved March 16, 2023, from
  7. Fernandes, C. (2021, August 16). Learn more about LBD from Lewy Body Dementia Association. Lewy Body Dementia Association. Retrieved March 16, 2023, from
  8. Mixed dementia. Alzheimer’s Disease and Dementia. (n.d.). Retrieved March 16, 2023, from
  9. Mayo Foundation for Medical Education and Research. (2023, January 18). Mild cognitive impairment (MCI). Mayo Clinic. Retrieved March 16, 2023, from,mental%20function%20has%20%22slipped.%22