Substance Abuse and Addiction in Parkinson’s Disease

Parkinson’s disease is the second most common chronic progressive neurodegenerative disorder, which comes to play as a result of the neurotransmitter dopamine deficiency caused due to an insult to the dopamine producing neurons, predominantly located in the nigrostriatal region of the brain. The dopamine, which is chiefly responsible to transport the chemical signals, control the muscular control and coordination, and hence its deficiency manifests as a constellation of motor function impairment symptoms.

The disease process is grossly incapacitating. Ranging from constipation, sleep disturbances to tremors, rigidity and eventually the loss of complete control over the muscle coordination, alongside the severe psychotic and behavioral disturbances, causes extreme depression in the Parkinson’s patients. The utter embarrassment due to loss of independence and self esteem, in adjunct to the compulsive behavioral disturbances push the patients in the pitfall of substance abuse and addiction.

There are various psychosocial factors that may lead to substance abuse and subsequent addiction and Parkinson’s patients are not immune to these pitfalls. However, it is interesting to not that some studies have shown that patients with Parkinson’s disease seem to have a low sensation seeking and a more law abiding personality trait which could protect them against the pitfalls of substance abuse and addiction.

When other factors are involved, such as the side effects of some anti-Parkinson medicines or other drugs, depression and other psychosocial factors which may be unique to a patient suffering with a disease like Parkinson’s disease, substance abuse can become a real possibility.

The question as to whether Parkinson’s disease is related to substance abuse is discussed below. Parkinson’s patients who are abusing any substance, whether a pharmaceutical drug or other illicit substance, should realize that the misuse and their addiction could negatively impact upon their condition. Apart from drugs interactions with Parkinson’s disease medicines, may drugs can contribute to or exacerbate the signs and symptoms of Parkinson’s disease or possibly even accelerate the progression of Parkinson’s disease.

For information on other forms of addiction – gambling, sex and so on, please refer to the article on Compulsive Behavior in Parkinson’s Disease.

Cigarette Smoking

There seems to be an inverse proportion to the number of cigarettes smoked and the development of Parkinson’s disease. It has been seen that patients with Parkinson’s disease are less likely to have ever smoked. Current smokers, in relation to ex-smokers, show this inverse relation better. The neuroprotective effect of cigarette smoke may be the reason for this, but should not prompt one to start smoking.

Caffeine Intake

Research also shows a decreased incidence of Parkinson’s disease in people consuming large amounts of caffeine, indicating that caffeine may have a neuroprotective effect too. Consuming 2 cups or more of tea per day, or 2 or more cola drinks per day may play a role in reducing the risk of Parkinson’s disease.

Alcohol Consumption

While it has been suggested that alcohol consumption may protect against Parkinson’s disease, there is no clear evidence to support this theory. Moderate beer consumption may lower the risk of developing Parkinson’s disease, but wine or liquor do not seem to offer any protection.

Drug Addiction

Research has shown a relationship between Parkinson’s disease and drug addiction. Parkinson’s disease patients sometimes become addicted to the drugs they are taking or develop various addictions as a result of their medication.

Parkinson’s disease patients lack dopamine, a neurotransmitter in the brain (a chemical messenger) which is responsible for motor movements as well as the ability to experience pleasure and pain. Dopamine is also involved with the reward pathway of the brain. Patients with drug addictions, on the other hand, have an excess of dopamine in their brain. This can explain how Parkinson’s disease patients, when treated with dopamine agonists (which increase the dopamine levels in the brain) start to show personality traits such as addiction which are normally alien to the patient. Treatment with levodopa does not usually produce such side effects.

Behavioral addiction in Parkinson’s disease

Parkinson’s patients are prone to develop dysregulation of the brain reward system which include addiction to the levodopa and impulsive control disorders (ICDs). The patients treated with dopamine agonists are two to three times at a greater risk to develop an ICD as compared to those treated by levodopa. ICDs are the behaviour addiction in Parkinson’s disease and include pathological gambling, compulsive buying, binge eating, and hypersexuality behaviour. It is not uncommon for the patients to have more than one ICD concurrently. These behaviours result in devastating psychosocial consequences for the patients and their families.

The conventional treatment for the behavioral addiction in Parkinson’s disease is usually not effective, as the decrement in the levodopa dosage to combat the behavioural disorders eventually leads to worsening of the motor aspects of the patient. The patient might develop worsening akineso-rigid syndrome and worsening of dyskinesia.

Narcotics

Narcotics such as morphine are sometimes given to Parkinson’s disease patients to alleviate pain not responding to any other treatment. Narcotics are often prescribed in combination with other drugs such as nonsteroidal anti-inflammatory drugs (NSAIDs). Although not usually dangerous in prescribed doses, the potential danger of addiction remains in such patients.

MPPP (1-methyl-4-phenyl-4-propionpiperidine), is an analogue of meperidine (a synthetic opioid), a street drug. During its illicit manufacture, MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) was inadvertently synthesized, whose use rapidly produced symptoms of Parkinson’s disease in the users, with toxicity leading even to death.

Methamphetamine

Methamphetamine is closely related to amphetamine but its effects on the central nervous system seem to be greater than those of amphetamine. It is an addictive, higly water soluble, CNS stimulant. Methamphetamine abuse has been linked to triple fold increased incidence risk of Parkinson’s disease. It affects the dopamine receptors in the brain, which leads to long-term impairment in dopamine function following the abuse of this drug. It causes a long term dopamine terminal damage and dopamine neuronal body loss, accompanied by reduced levels of dopamine and its metabolites. It induces neurotoxicity in a dose dependant manner, and its toxicity is persistent. Neuroimaging studies have shown that the meth abusers have shown decreased levels of dopamine and dopamine transporters, as well as structural changes similar to those observed in the PD in nigrostriatal and other regions of brain.

The drug, triggers the pleasure centres and causes an intense euphoria, along with the feeling of generalized well being, increased physical activity, energy and alertness, and decreased anxiety. These effects are observed immediate to the drug consumption and lasts for hours. Patients attempt to repeatedly access this profound euphoria by the intake of drug and eventually establish an ongoing pattern of substance abuse.

Cocaine

Parkinson’s disease has been commonly known as a neurodegenerative disease of the old age. However, recent studies have established the occurrence of Parkinson’s in young individuals who are chronic cocaine abusers. Studies show that cocaine-users may be more at risk of developing Parkinson’s disease. Pregnant women abusing cocaine could be at increased risk of giving birth to children who will develop Parkinson’s disease later in life.

Cocaine is known to cause the build up of signalling molecule dopamine in the brain, leading to a persistent stimulation of dopamine sensing neurons. This overload leads to the damage of the cells that respond to dopamine, causing the similar manifestation of symptoms as in PD. Chronic cocaine abusers have also been shown to demonstrate the presence of clumps of protein alpha-synuclein, which is one of the characteristic diagnostic hallmark in Parkinson’s disease.

Related Article

  1. Compulsive Behavior in Parkinson’s Disease

References

  1. Alcohol Consumption and the Incidence of Parkinson’s Disease
  2. Parkinson’s Disease Risks Associated with Cigarette Smoking, Alcohol Consumption and Caffeine Intake

 

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