Everyone with eyes and a brain of their own knows that dementia is a very common and serious problem, robbing some people of their memories, ability to function independently and even their personalities. As a community-based neurologist, I see all too many cases of dementia, but the part that worries me the most is when patients, family members and even medical personnel assume that nothing can be done and don't even bother to evaluate for underlying causes.

So how do dementia specialists or other doctors investigate cases of dementia? The medical detective-work begins with a thorough history and physical examination.

After compiling the results of the history and examination, the physician can usually judge the relative likelihoods of different underlying causes for the dementia, but follows up these clinical judgments with additional medical tests to nail down the most likely cause. The irreducible minimum of additional testing includes a brain scan--either a CT or an MRI--plus a panel of blood tests.

Other tests can be applied depending on the physician's judgment of their usefulness in individual cases. These might include an electroencephalogram (brain-wave test), lumbar puncture (spinal tap) or a PET (positron emission tomographic) scan, which is a newer technique that shows the relative activity of brain cells in different parts of the brain. Additional blood-tests can screen for infections with human immunodeficiency virus (HIV) or the bacteria associated with Lyme disease or syphilis.

It's the other half of the cases which reveal an interesting grab-bag of different underlying causes and, for that matter, treatments.

Normal pressure hydrocephalus is another cause of dementia responding to neurosurgery, but in this condition the surgeon doesn't remove a mass-lesion. Instead, the surgeon places a tube inside one of the brain's swollen fluid-chambers known as ventricles, allowing the excessive fluid-accumulation to drain away through the tube and into another body-space where it causes no harm. Normal pressure hydrocephalus can be identified not only by its dementia and enlarged ventricles, but by the concurrent presence of a prominent walking impairment as well as urinary incontinence.

As people get older and acquire more medical problems, their list of medications often grows longer. One or more of the medications they take might interfere with mental functioning. Common offenders are medications for urinary incontinence, anxiety or insomnia. If a problem-medication is eliminated, or replaced with another drug, the patient's mental prowess can improve.

Chronic infections with the Lyme and syphilis bacteria can be resolved with appropriate antibiotics. Occasionally a fungal infection is to blame, and can also be treated with specific medication. Treatments for HIV are less good, but this disease still needs to be identified in order to obtain the best possible outcome.

Strokes can also produce dementia. Strokes are caused by disrupted circulation which damages parts of the brain. In most cases, the patient and family were aware of strokes when they occurred, but in other cases one or more strokes might have gone undetected at the time they occurred. Prior strokes cannot be undone, but recognition of the presence of strokes can lead to preventive measures to decrease the likelihood of future strokes.

(C) 2005 by Gary Cordingley