PSP is a little-known degenerative brain disease which progresses rapidly and is unresponsive to drugs, but it is often misdiagnosed as Alzheimer's or Parkinson's, writes Eoin Burke-Kennedy
Sandra Campbell thought her father,William, was suffering from depression when be began to exhibit severe mood swings in his early 60s.
He was loathe to admit there was something wrong but the family noticed a change in his personality, Campbell says. "He seemed withdrawn and distracted."
He was persuaded to see the doctor on several occasions over the course of a year, but routine check-ups found nothing untoward. It was when be began to have unexplained falls and problems with his orientation that a local GP suspected an atypical neurological condition.
He was referred to a neurologist in Belfast who diagnosed the problem as progressive supranuclear palsy (PSP), a degenerative brain disease which results in the gradual loss of movement.
In its early stages, the condition mimics Parkinson's disease and to a lesser extent Alzheimer's disease. Consequently, it is often misdiagnosed.
Little is known about the disorder - even among healthcare professionals - but it has the same prevalence in society as motor neuron disease, which affects about five people in 100,000.
It occurs in men and women in equal frequency, usually in their late 50s or 60s. However, there are rare cases of early onset PSP in people in their 40s. Unlike Parkinson's disease, it progresses at a rapid rate and, unfortunately, is unresponsive to drugs.
Life expectancy is typically five-seven years from onset of symptoms - not from diagnosis.
Campbell's father died in 2003 - five years after his initial symptoms presented - but she believes her family was fortunate in having him diagnosed early.
One of the main risks associated with PSP is the propensity for patients to fall because the disease impairs balance.
Campbell, who is now the North's regional development officer for the UK's PSP Association, says: "These falls - which are usually backwards and always without warning - can and have been fatal."
Because PSP also affects short-term memory, patients often forget the risk of being on their feet and get up out of their chair on their own, she says.
She tells of one patient from the northeast who was left alone for a matter of minutes. He rose from his seat only to fall though a glass door and subsequently die from his injuries.
"Because the disease is relatively unknown and very often misunderstood, our patients are very often at risk even when they go into care homes for respite care," she says.
Another classic symptom of PSP, and one from which it gets its name, is a weakness or palsy of eye movements, particularly in the downward direction. Sufferers have restricted vision but not blindness, as it is the muscles of the eye that are affected.
The condition is sometimes referred to as the Mona Lisa syndrome because patients seem to blink less and often appear to be staring.
While global data for PSP is limited, it does seem to be ubiquitous across countries, in that there is no one population that suffers more.
Consultant neurologist at the Mater hospital Dr Tim Lynch explains that with Parkinson's disease, sufferers lose brain cells from an area at the top of the brain stem known as the substantia nigra. But as well as losing these cells, PSP patients suffer degeneration in several other parts of the brain, especially in the region at the back of the brain involved in balance.
"The patients fall much earlier in PSP and have balance difficulties much earlier than in Parkinson's disease. And then over time they go on to develop other things including eye movement problems due to the brain stem involvement. So it's a more diffuse disorder in that it is not as localised as Parkinson's disease," he says.
"From a sociological point of view, not only does it affect movement and balance, but also patients' motivation, initiative and drive - they often become a little bit more apathetic and less empathetic," he says.
"Sufferers become less interactive, often just sitting there quietly, not communicating with their spouse or family.
"This is one of the things that really upsets the family of patients as their loved one is becoming more and more withdrawn and appears to be less caring because the condition can affect the region of the brain which controls that emotion."
Lynch says there are no therapies that make a big difference in combating PSP.
"We can do a few tricks with different pills to relieve the symptoms, but so far we do not have any therapy that stops the disease or reverses it. But then again, this is true of many of our neurological problems.
"The outlook for sufferers is variable. You can have some people with PSP living for many years and others getting into trouble very quickly, but median line survival is five-seven years."
Lynch sees about 100 people with the condition but he believes it is grossly under-diagnosed and that this may be just the tip of the iceberg. "Getting a diagnosis, or getting information or acting on information in this country is difficult because of the limited neurological services," he says.
The cause of PSP is not yet known but recent research has linked some cases of the disease to a mutation of a gene which produces a protein in the brain called tau, which is necessary for cell function.
The gene was discovered in 1998 in a study on an Irish family, resident in the US, who had a familial neurological condition similar to PSP.
Lynch, who was part of the original research team, says they identified a mutation in the tau gene which resulted in the production of a specially formatted protein.
The discovery resulted in a major explosion in the field of tauopathy - a rubric term which refers to PSP or PSP-like neurological conditions that have abnormal tau.
Lynch says: "There are now a number of pharmaceutical companies endeavouring to develop an anti-tau agent that would try to stop this abnormal production of the protein."
But he believes the cause of PSP may ultimately prove to be a combination of genetic predisposition and environmental triggers similar to what much of the research into Parkinson's disease is pointing to.
The first European trial of a therapy for PSP is ongoing. The drug being tested is an anti-oxidant traditionally used in the treatment of Parkinson's disease. "We are hoping that the trial is going to spit up something helpful," Lynch says.
Maggie Rose, who has been a PSP nurse specialist in England for 11 years, runs a 24-hour telephone helpline for patients and carers. She says PSP is a progressive condition which involves a very high level of caring.
Patients are usually wheelchair-bound and often have to be hoisted from bed to chair and tube-fed, especially in the later stages of the disease.
"Carers may be trapped 24 hours a day in a house with somebody who is unable to communicate, who may be frustrated, irritable and certainly withdrawn," Rose says.
She explains that patients suffer cognitive change or subtle personality change but no dementia. "Intelligence remains intact but the personality changes, so from the point of view of the family, you end up living with a stranger," she says.
The PSP Association is holding a seminar in Dublin on August 29th at the Gresham Hotel. Representatives will meet Parkinson's disease specialist nurses working in the Republic to talk to them about PSP.
For further information on PSP:
PSP European Association: www.pspeur.org
The US Society for Progressive Supranuclear Palsy: www.psp.org
UK helpline, tel: (0044) 1939 270889
UK PSP Association, tel: (0044) 1327 860299.