Alzheimer's is the most common cause of dementia – in fact, almost two-thirds of dementia cases are due to Alzheimer's disease. However, a host of other conditions can also cause dementia, including the 10 described below.
Sometimes, dementia is due to multiple medical conditions. In these cases, it's often called mixed dementia. The most common form of mixed dementia is due to both Alzheimer's and vascular disease. Because dementia can be due to so many disorders, obtaining an accurate diagnosis is imperative in order to properly treat the dementia.
1. Creutzfeldt-Jakob disease (CJD)
Photo © CDC/Teresa Hammett
Sometimes referred to as mad cow disease, CJD is caused by slow viruses called prions, which are folded proteins that interfere with the brain's ability to function. Between 5% and 15% of CJD cases have a genetic link, usually affecting adults between 40 and 60 years of age. Still, CJD can occur at any time, and many cases have no genetic link; instead, the disease is transmitted through infected medical equipment in procedures such as corneal transplantation. Dementia due to CJD often progresses rapidly over several months and involves problems with attention, concentration, appetite, vision and coordination.
2. Head Trauma
Dementia due to head trauma can result from a single major head injury or from repeated head injuries, such as in professional sports. The degree and nature of impairment depends on the location and severity of the brain injury. People with dementia due to head trauma often experience amnesia, memory loss, irritability, attention problems, depression, apathy, and other personality changes. This kind of dementia is most common among young males who engage in risk-taking behaviors.3. HIV/AIDS
Photo © CDC/Dr. Edwin P. Ewing, Jr.
HIV/AIDS can destruct the tissue and structures of the brain in such a way that dementia results. Common symptoms of dementia due to HIV/AIDS include forgetfulness, slowness, and difficulties with concentration and problem solving. Symptoms might also include apathy, delusions, and hallucinations. Because HIV/AIDS affects all ages, dementia due to HIV/AIDS can occur in children as well as adults.
4. Huntington's Disease
Huntington's disease is an inherited condition affecting cognition, emotion, and movement. It can occur as early as 4 years of age or as late as 85 years of age, but it usually develops in the late 30s or early 40s. The primary symptoms of dementia due to Huntington's are difficulty retrieving memories, problems with executive functioning, and impaired judgment. Memory problems become more severe as the disease progresses, and delusions and hallucinations may occur. Children of those with Huntington's disease have a 50% chance of also developing the disease.5. Lewy Body Disease
Photo © Lewy Net, University of Nottingham
Lewy body disease is characterized by deposits of the protein alpha-synuclein inside brain cells. These deposits impair perception, thinking, and behavior. The deposits are called Lewy bodies, named after Friederich H. Lewy, who first described the deposits in the early 1900s. Lewy bodies are also found in the brains of those with Parkinson's and sometimes those with Alzheimer's, making diagnosis more complicated. Three symptoms set Lewy body disease apart from other types of dementia: vivid visual hallucinations, fluctuating alertness, and severe sleep problems, including acting out one's dreams or making severe involuntary movements.
6. Normal Pressure Hydrocephalus
Normal pressure hydrocephalus occurs when there is an abnormal increase in cerebrospinal fluid in the brain's cavities, which puts pressure on the brain. In addition to typical symptoms of dementia, people with dementia due to normal pressure hydrocephalus often experience problems with walking and balance, as well as impaired bladder control.7. Parkinson's Disease
Photo © A.D.A.M.
Parkinson's disease is a neurological condition affecting movement by creating tremors, rigidity, and other problems with balance and motor skills. In the advanced stages, Parkinson's often affects cognitive functioning, resulting in dementia in 20-60% of those with the disease. Dementia due to Parkinson's involves difficulty retrieving memories, depression, and problems with executive functioning. Interestingly, some people with dementia due to Parkinson's have been found upon autopsy to also exhibit brain pathology indicating Alzheimer's disease or Lewy body disease.
8. Pick's Disease
Pick's disease is the most common of the frontotemporal dementias, which affect the frontal and temporal (side) lobes of the brain. Most commonly occurring between 50 and 60 years of age, Pick's disease involves drastic personality changes, deterioration of social skills, and a lack of empathy and emotion. These signs usually occur before problems with memory and other typical signs of dementia. In the advanced stages of the disease, the person may become extremely apathetic or agitated, to the point that conducting a diagnostic workup is too difficult.9. Vascular Dementia
Photo © A.D.A.M.
Vascular dementia is the second most common form of dementia and results from impaired blood flow to the brain. This can occur either by a narrowing or complete blockage of blood vessels in the brain, which deprives brain cells from the nutrients and oxygen they need to function. Vascular dementia can result from several small strokes that occur over time, after a single major stroke, or from conditions that don't block blood vessels, but simply narrow them, such as diabetes or hypertension. Vascular dementia often progresses in a step-wise fashion. For example, the person might stabilize for a period of time, then suddenly get much worse, then continue to alternate between stable periods and sudden drops in functioning.
10. Wernicke-Korsakoff Syndrome
Wernicke-Korsakoff syndrome results from a deficiency in thiamine (Vitamin B1) and is often due to chronic, severe alcoholism. It can also result from general malnutrition, eating disorders, or the effects of chemotherapy. Dementia due to Wernicke-Korsakoff syndrome involves confusion, apathy, hallucinations, communication problems, and severe memory impairment.11. Sources
American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author.Vascular Dementia. Mayo Clinic. 2007. http://www.mayo clinic.com/print/vascular-dementia/DS00934/DSECTION=all&METHOD=print
What is Lewy Body Dementia? Lewy Body Dementia Association. 2007. http://www.lewybodydementia.org/lbdinfo.php
