# The Most Common Types of Dementia and Their Warning Signs, Explained by Experts
Dementia isn't one disease. It's a group of conditions marked by decline in thinking, memory, and behavior. Understanding the different types helps people recognize warning signs early.
Alzheimer's disease accounts for 60 to 80 percent of dementia cases. It develops when proteins build up in the brain, damaging nerve cells over time. Early signs include forgetting recent conversations, repeating questions, and getting lost in familiar places. Many people assume memory loss defines dementia, but that's incomplete.
Vascular dementia, the second most common form, results from reduced blood flow to the brain after strokes or smaller vessel damage. Symptoms include difficulty concentrating, slowed thinking, and mood changes. The onset can be sudden or gradual, depending on when blood vessels are affected.
Lewy body dementia causes deposits of a protein called alpha-synuclein to accumulate in brain cells. This type produces hallucinations, sleep disturbances, and movement problems. People often see things others don't, or experience rigid muscles and tremors similar to Parkinson's disease.
Frontotemporal dementia damages the frontal and temporal lobes, areas controlling personality and language. Early warning signs include inappropriate behavior, loss of empathy, difficulty finding words, and speaking less. This form often strikes people in their 50s and 60s, earlier than other dementias.
Mixed dementia occurs when brain changes from multiple dementia types exist simultaneously. Autopsies reveal about one-third of dementia cases involve pathology from at least two types.
Beyond memory loss, watch for these red flags. Changes in personality, judgment problems, difficulty with familiar tasks, confusion about time or place, and communication struggles all warrant medical attention. Some people become withdrawn or anxious