Houston Methodist. Leading Medicine.
Houston Methodist. Leading Medicine

Nantz National Alzheimer Center

Understanding Different Kinds of Dementia

Dementia is not a disease itself, but a group of symptoms that are caused by various conditions. Dementia is marked by cognitive decline: the loss of memory and thinking ability that interferes with everyday life. It can also fundamentally change a person’s personality, mood and behavior.

Alzheimer’s disease (AD) is the most common cause of dementia. In some cases, however, other factors or diseases can produce dementia. The most common causes after AD include vascular dementia, Lewy body dementia, frontotemporal dementia, Parkinson's disease and Huntington’s disease.

It is important to see a physician who specializes in dementia, memory-related illnesses or geriatrics when you notice that you or your loved one is showing signs of forgetfulness that interfere with daily life. Most dementias cannot be cured or reversed yet, and there is a great need for research that will lead to a cure. However, there are medications that can slow the progression of the disease and help manage many of the symptoms. Importantly, there are services that can greatly help the caregiver, as well.

Vascular dementia impairs a person’s thinking, reasoning, planning and memory because of reduced blood flow to the brain. Strokes or other damage to blood vessels feeding the brain can cause brain damage that results in vascular dementia. Risk factors for vascular dementia are the same as those for cardiovascular diseases: high blood pressure, heart disease, diabetes, smoking and high cholesterol. Controlling these risk factors can help prevent vascular dementia, as well.

Lewy body dementia (LBD) impairs a person’s ability to think, causes visual hallucinations, and produces symptoms that are similar to Parkinson’s, including tremors and rigid muscles. It is characterized by proteins that develop near the brain stem and spread to the cerebral cortex and other parts of the brain. Certain brain chemicals are altered, damaging the patient’s perception, thinking and behavior. There is no cure for Lewy body dementia. Specialists help mitigate the symptoms of LBD with medications.

Frontotemporal dementia is caused by a deterioration of the frontal and anterior temporal lobes of the brain, the parts of the brain that control personality, behavior, language, movement and sometimes memory. It is characterized by a relatively abrupt change in personality and behavior. It usually strikes earlier than AD, between the ages of 40 and 65. Treatment focuses primarily on medications that can help manage symptoms.

Normal pressure hydrocephalus (NPH) is a rare condition caused when excess cerebrospinal fluid (CSF) is trapped in the ventricles of the brain. The excess fluid causes pressure on the brain and typically results in impairment of memory, gait and bladder control. It can be treated to some extent with a shunt that drains the excess CSF into the abdominal cavity, where it can be absorbed safely. Response to treatment varies in each individual.

Parkinson’s disease is a progressive disorder of the nervous system. Changes motor skills - hand tremors, stiff or rigid muscles, short gait and slowed movements – are the most familiar signs of the disease. However, non-motor symptoms are becoming more evident. Non-motor symptoms include dementia, depression, anxiety and sleep difficulties.  Medications can alleviate some of the symptoms. Surgery called deep brain stimulation can help with tremors in patients who don’t respond well to medications.

Huntington’s disease is a genetic, progressive neurodegenerative disease that causes dementia as well as significantly impaired movement and psychiatric disorders. Both voluntary and involuntary movement is affected. The patient can lose the ability to plan, make new memories, think and converse with others. Clinical depression is common, as is a lack of impulse control and obsessive-compulsive disorder (OCD). Medications, psychotherapy, speech therapy and physical therapy can help alleviate some of the symptoms.

Some conditions that cause dementia can be treated and cured. Certain forms of substance abuse, medication interactions, hormone imbalances, infections and deficiencies in vitamin B12 or folic acid can cause dementia. Depending on the severity of the condition, dementia caused by these factors can be improved or cured.