The article presents a case of a teenage female patient illustrating the difficulties of diagnosis and treatment of mental pathology at the onset of juvenile parkinsonism, which developed as a result of compound heterozygous mutations and proceeds with moderate akinetic-rigid and pseudopyramidal syndromes and combined tremor. It is shown that before the appearance of distinct symptoms of parkinsonism and the genetic study that confirmed the diagnosis, the patient had been observed for several years with various psychiatric diagnoses and received psychotropic therapy. This case demonstrates the difficulties of differential diagnosis of juvenile parkinsonism in children at the initial stage due to multiple comorbid motor, affective and behavioral disorders. When neurological symptoms appear in patients, a multidisciplinary approach is required, including joint diagnostics by psychiatrists and neurologists to establish an accurate diagnosis and select the optimal therapy. The introduction of principles of interdisciplinary interaction in the management of such patients will improve the timeliness of diagnosis and pathogenetically based therapy.