Parkinson's disease and similar movement disorders

What are Parkinson's disease and Parkinsonism?

Instructions relating to movement are sent from the motor areas of the cerebral cortex through the pyramidal pathway to activate muscles so that a planned movement can actually be executed. The stimulation of other parts of the brain outside the pyramidal pathway (and in particular the basal ganglia located deep in the brain) plays a role in motor performance. This is known as the extrapyramidal system.

A disease like Parkinson's, but also poor circulation and certain types of medication (such as antipsychotics), interfere with the functioning of the extrapyramidal system. Parkinson's disease (which is caused by decreased dopamine production in the basal nuclei) is distinct from Parkinsonism. Parkinsonism is accompanied by the same symptoms as Parkinson's disease but it is caused by damage to the basal ganglia (by medication, for example).

What are the complaints associated with Parkinson's disease and Parkinsonism?

Trembling (especially at rest), stiff, sometimes painful, muscles, a 'rigid', mask-like facial expression, difficulty with getting moving and stopping, slow, hunched and shuffling gait. Balance is impaired and so there is an increased risk of falls. The severity of complaints can vary. Parkinson's disease is associated with an increased risk of depression.

In Parkinsonism caused by medication (such as antipsychotics), inactivity and stiffness predominate. The complaints are perceived as hypokinesia (the feeling of being strapped in), fatigue, muscle weakness, and sometimes pain in the muscles and joints. There is also impaired mimicry, less swinging of the arms when walking, bent shoulders and monotonous speech.

Antipsychotics cause Parkinsonism in 15 to 50% of the people who take them and they can also result in the following extrapyramidal side-effects: acute dystonia (10 to 100%), rabbit syndrome (2 to 10%), acathisia (20 to 50%) and tardive movement disorders (1% in adolescents and 5 to 7% in older people). ¹³⁵

• Acute dystonia: contractions of muscle groups, particularly in the head and neck, often asymmetric and resulting in a twisted neck, difficult with talking and swallowing, lockjaw and fixed gaze.
• Rabbit syndrome: tremor around the mouth resembling the chewing movements made by rabbits
• Acathisia: subjective feeling of unrest that results in wiggling, rocking, an inability to remain seated and anxiety
• Tardive movement disorders: movement disorders caused by a prolonged use of antipsychotics such as worm-like movements of the tongue, smacking, chewing movements of the jaws, uncontrolled movement of the torso.

People with intellectual disabilities sometimes find it impossible to communicate these symptoms. The people around them may mistakenly interpret what they observe as a change in behaviour.

How common are Parkinson's disease and Parkinsonism in the general population?

The Rotterdam ERGO study of people aged 55 and over found a prevalence rate for Parkinson disease and Parkinsonism of 1.9%, three-quarters of which was accounted for by Parkinson's disease. The number of people with these symptoms increases with age. ¹³⁶

In a large open-population study looking at 220,000 people of all ages in Portugal, the prevalence rate for Parkinson's disease was 0.14% for men and 0.13% for women. ¹³⁷

How common are Parkinson's disease and Parkinsonism in people with intellectual disabilities?

No statistics have been found for the prevalence of Parkinson's disease in people with intellectual disabilities. There are strong grounds for assuming that Parkinsonism and other extrapyramidal movement disorders are linked to an increased use of psychopharmaceuticals.
A Dutch study of three institutions housing 2373 people with intellectual disabilities showed that 32.2% took antipsychotics. ¹³⁸

Side-effects such as Parkinsonism and other extrapyramidal movement disorders are often seen in combination with the use of these types of medication but they are not adequately recognised. ¹³⁹
A Dutch study of 99 adults with intellectual disabilities who used antipsychotics for at least one year due to behaviour problems found that 53% of them had extrapyramidal side-effects. ⁴⁸⁸

Another Dutch study that looked at 103 adults with intellectual disabilities and severe behaviour problems (78% of whom used psychopharmaceuticals) observed neurological symptoms (epilepsy, paresthesia or movement disorders) in 34%. Increasing use of psychopharmaceuticals was associated with more frequent neurological symptoms (as side-effects). ⁴⁸⁹