Alzheimer’s disease and dementia caused by cerebrovascular disease are the conditions that most commonly interfere with thinking, but there are many others. Some, like Alzheimer’s, result from misshapen proteins in the brain and tend to get worse over time. Examples include frontotemporal dementia and Lewy body dementia
Dementia can also result from tumors, head injuries, infections, medications or poisons. Getting too little of vitamins B1, B6 or B12 can contribute to dementia, as can lack of oxygen from problems such as asthma or a heart attack. Many of these dementias are treatable.