Michael J. Fox mistook first Parkinson’s symptom as hangover at 29

Michael J. Fox heartbreakingly mistook his first symptom of Parkinson's disease as a hangover.

The celebrated actor, best known for his role as Marty McFly in the Back to the Future franchise, received the shock diagnosis at just 29 years old in 1991.

Now 64, he has embarked on an impressive career despite living with the progressive neurological disorder.

Even more remarkably, the Hollywood icon has raised more than $2 billion for Parkinson's research via his Michael J. Fox Foundation.

And in his most recent memoir, Future Boy, the star offers up the most unflinching account of his Parkinson's experience and its impact on his career yet.

In one excerpt, he details the way he'd like to die after living with the devastating health condition for nearly 35 years.

Michael J. Fox was diagnosed with early-onset Parkinson's in 1991 (Ron Galella/Ron Galella Collection via Getty Images)

Parkinson's disease is a movement disorder of the nervous system that worsens over time.

The risk of developing the condition tends to increase with age, the Mayo Clinic says, while factors like genetics and being male can also have an impact.

While it sadly can't be cured, medicines may help symptoms get better and make living with it more manageable.

The Mayo Clinic adds that symptoms tend to start out subtle and in one side of the body before progressively getting worse.

Fox previously recalled how he initially dismissed an early warning sign of Parkinson's as a hangover.

The actor has always been candid about his life with Parkinson's (Jason Kempin/Staff/Getty Images)

Waking up one morning in 1990, Fox noticed his little finger shaking and put it down to the previous night of heavy drinking.

It was a period when he was out partying constantly, and at such a young age, Parkinson’s was the last thing on his mind.

When the symptom persisted, a doctor chalked it up to an accident Fox had had on the Back to the Future III set, in which he caught his neck in a rope.

A year and countless tests later, Fox was diagnosed with early-onset Parkinson's disease.

His first reaction was, simply, 'hide', the Guardian reports.

Up until that point in his life, Fox had considered himself a lucky man.

What are the symptoms of Parkinson's disease?

A tremor can be a common warning sign (Bymuratdeniz/Getty Images)

The Mayo Clinic lists eight main Parkinson's symptoms to be aware of.

These include:

• Tremor, beginning in the hands, fingers, jaw or foot
• Slowed movement and less expression in the face
• Stiff, painful muscles
• Stooped posture and balance problems
• Loss of automatic movements, like blinking, smiling or swinging your arms when you walk
• Speech changes
• Changing handwriting which is smaller and more cramped
• Non-motor symptoms such as depression, anxiety, constipation and sleep problems.

If you have any concerns, contact your doctor.