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Dopamine Dysregulation Syndrome (DDS) is a condition characterized by compulsive use of dopaminergic medications in patients with Parkinson’s disease undergoing long-term dopamine replacement therapy (DRT), with an average onset age of around 60 years. Currently, there are few reports on the incidence of DDS, not only due to limited awareness of this syndrome among patients and doctors but also because patients often conceal their symptoms. Reports from abroad indicate an incidence of about 4% among Parkinson’s disease populations.
This condition was first described by Giovannoni et al. in 2000 as “hedonistic homeostatic dysregulation syndrome” and is a neuropsychiatric disorder associated with drug abuse or addiction. PD patients may inappropriately overuse dopaminergic medications to escape the depressed and anxious states associated with “off periods,” leading to cravings, addiction, and dependence. The main manifestations include patients increasing their dopaminergic medication use on their own or requesting higher doses from their doctors, or increasing the dosage without the doctor’s consent, resulting in psychological disorders similar to those caused by long-term abuse of stimulants, ultimately affecting social and occupational functioning.
Behaviors Related to DDS
➤ Drug addiction behavior: Refers to the compulsive use of dopaminergic medications by PD patients.
➤ Stereotypic behavior (punding): A repetitive, purposeless, and meaningless behavior, such as being obsessed with repeatedly manipulating a mechanical device, repeatedly repairing and disassembling television or radio components, aimlessly driving or walking, or repeatedly cleaning and organizing items.
➤ Impulse control disorders (ICD): A series of behavioral disorders characterized by an inability to resist temptation and impulses, even when these behaviors may harm oneself or others. The ICDs associated with excessive use of dopaminergic medications in PD patients mainly include pathological gambling, compulsive eating, compulsive shopping, and compulsive sexual behavior. However, ICD cannot be diagnosed as DDS if it is not accompanied by compulsive use of dopaminergic medications.
Diagnostic Criteria
The diagnostic criteria for DDS established by Giovannoni et al. in 2000 are:
(1) PD patients with good therapeutic effects from levodopa;
(2) Need for excessive doses of levodopa;
(3) Pathological drug use: Despite the presence of dyskinesia during “on periods,” there is still a need to increase the DRT medication dose; unwillingness to reduce the medication dose; no painful dystonia;
(4) Impairment of social and occupational functioning: fighting, violent behavior, loss of friends, job loss, deterioration of family relationships;
(5) Mania and bipolar disorder related to DRT;
(6) Related behavioral disorders persist for at least 6 months.
Treatment and Management
Managing DDS patients presents a challenge for clinicians. First, patients often have difficulty recognizing their abnormal behaviors and their relationship with medication treatment; additionally, how doctors can adjust medication regimens over the long term without causing resistance from patients is a tricky issue; currently, there are no specific medications targeting this aspect. When encountering DDS patients in clinical practice, treatment can be approached from the following aspects.
1. Identify Abnormal Behavioral Manifestations and Provide Psychosocial Support
Psychosocial therapy includes emergency management, relapse prevention, family support management, and general behavioral therapy (CBT), which have been shown to be helpful for drug abusers. For patients with severe DDS, collaboration between neurology and psychiatry experts can be beneficial in controlling symptoms; on the other hand, family members should be persuaded to supervise patients, limiting access to finances, the internet, etc., to prevent pathological gambling and internet addiction.
2. Pharmacological Treatment
Adjustment of treatment medications should first involve stopping or reducing the use of dopaminergic medications, especially levodopa preparations such as Sinemet and Madopar. The principle of pharmacological treatment for DDS still advocates for the “minimum drug dosage, optimal satisfactory effect,” aiming to control PD symptoms while avoiding the emergence of abnormal behaviors. The use of subcutaneous apomorphine and short-acting dopaminergic medications should be avoided.
For depressive and anxious symptoms arising from withdrawal in DDS patients, antidepressant treatment may be necessary, but currently, there are no effective medications for depressive symptoms in DDS patients; additionally, patients with mild mania and psychiatric symptoms accompanying DDS may require inpatient treatment. Amantadine is generally used to treat dyskinesia, but recent studies have found that it can reverse stereotypic behaviors in PD patients, though this effect needs further verification.
3. Surgical Treatment
In addition to the pharmacological treatments discussed above, there is still controversy regarding the treatment of dopamine dysregulation syndrome with subthalamic nucleus deep brain stimulation (STN-DBS) or medial pallidum stimulation. Both surgical methods can significantly improve motor symptoms in “off period” patients and significantly reduce the daily dosage of required dopaminergic medications. The possible mechanisms of surgical action for DBS remain unclear, and it may relate to the reduced demand for DRT medications post-surgery. Surgical treatment is suitable for patients with earlier onset and severe motor fluctuations accompanied by DDS.
DDS is a relatively rare iatrogenic disease, currently lacking sufficient understanding and diagnosis, but the behavioral disorders caused by DDS can lead to destructive social adverse consequences, thus requiring attention to improve recognition rates and formulate reasonable treatment strategies.
References:
1. Yan Lei, Liu Weiguo. Dopamine Dysregulation Syndrome [J]. Stroke and Neurological Diseases, 2016, 23(6):465-467.
2. Gui Xiaohong, Luo Wei. Dopamine Dysregulation Syndrome [J]. Chinese Journal of Neurology, 2011, 44(2):135-137.
3. Li Fengqun, Peng Guoguang. Epidemiology of Dopamine Dysregulation Syndrome in Parkinson’s Disease [J]. Frontiers in Medicine, 2012(33):106-107.
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