[Neuropsychiatric manifestations in Parkinson's disease].

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease affecting 1-2% of the population over 60. Although diagnosed by its characteristic motor manifestations, PD may be preceded, and is frequently accompanied, by a wide range of psychiatric and cognitive symptoms. These symptoms are often more debilitating than its motor complications and it is nowadays appreciated that they can be an important cause of excess disability in PD, frequently necessitating hospitalization and institutionalization. Despite their frequent occurrence, most PD-related neuropsychiatric symptoms remain under-recognized and undertreated in clinical practice and their diagnosis is challenging because of the overlap of the somatic features of the psychiatric disorders and the motor symptoms of PD. Even when identified, there is a common perception that many of these symptoms are untreatable. Their recognition is essential not only for ascertaining the functional status of patients but also for better appreciating the nature of the neurodegenerative process in PD. These symptoms may precede the onset of motor symptoms and can be used as screening tools allowing for very early disease identification and for trials of possible diseasemodifying interventions. The pathophysiology of neuropsychiatric symptoms in PD involves complex and multifactorial mechanisms, including disease-related and psychological factors. Alterations in neurotransmitters like dopamine, serotonin, acetylcholine, involving subcortical projections and synaptic and neuronal changes involving limbic and cortical structures combine to result in these nonmotor symptoms. Potentially earlier evaluation and treatment of comorbid psychiatric and cognitive disorders in PD could improve quality of life and patient productivity, reduce morbidity and caregiver burden, and minimize healthcare costs. Management strategies include adjustment of dopaminergic medication, use of psychotropic treatments and behavioral and psychological interventions. Dopaminergic medication may precipitate neuropsychiatric conditions, such as the dopamine dysregulation syndrome. The choice of psychotropic medication for the neuropsychiatric symptoms of PD is determined by a balance between potential benefit versus side effects, mostly in terms of worsening motor symptoms. Furthermore, treatments used in general psychiatry services may not be as effective in PD. This article provides an overview and focuses on the neuropsychiatric manifestations in PD including depression, anxiety, psychosis, apathy and fatigue, personality, sexual dysfunction, sleep disorders, cognitive impairment and dementia, impulse control disorders and related behaviours. The epidemiology, pathophysiology and risk factors, clinical presentation and management of the most common neuropsychiatric complications in PD are discussed.