Creutzfeldt-Jakob largely unknown
DEAR DOCTOR: Could you please explain Creutzfeldt-Jakob disease? Some people call it “mad cow disease,” which gives it a stigma. I lost my twin brother to this disease, and it’s left our family shattered.
DEAR READER:
Creutzfeldt-Jakob disease (CJD) is the most common prion disease in humans. (The others are predominantly found outside the United States.) Prions are infectious, but they’re not viruses or bacteria; they’re proteins. They appear to be created from normal proteins found on cell membranes. The normal proteins may help inhibit cell death, but in prion diseases, they reconfigure. This initial change is believed to be related to an external agent, possibly a virus, chemical or drug, in 85 percent to 95 percent of patients and to a genetic cause in 5 percent to 15 percent of patients.
The term “mad cow disease” is actually a misnomer, because the majority of cases are not related to prion transmission between cows and humans. It can happen, of course, such as the 1990s outbreaks in the United Kingdom that led to the term.
Regardless of the cause, exposure to
abnormal prions leads to a cascading effect — the creation of more abnormal prions that disrupt nerve cells’ function and lead to their death. This destruction causes holes within the brain tissue, leaving it with a spongelike appearance.
The disease initially interferes with concentration, memory and judgment and leads to episodes of sleep throughout the day. In terms of mood, a person may at first seem neglectful, apathetic and depressed, quickly giving way to unrelenting mental deterioration. Patients eventually develop dementia and can lose the ability to control muscle movements, resulting in twitching or jerking contractions of the muscles. Progression is slower for people younger than 50, but regardless, death usually occurs within one year of symptom onset, with an average time to death of six months.
The only positive in this scenario is that CJD is rare, affecting one in a million people per year.