Effectiveness of aripiprazole in a patient with presumed idiopathic Parkinson's disease and chronic paranoid schizophrenia

Abstract

SEVERAL CASES OF the coexistence of schizophrenia and idiopathic Parkinson's disease (IPD) have been reported and the management of concurrent psychosis and parkinsonism has been considered as quite difficult as even atypical antipsychotics may worsen parkinsonism; conversely L-dopa may worsen psychosis.1, 2 To my knowledge, this is the first case report of successful treatment with aripiprazole in a schizophrenic patient with comorbid IPD. A 71-year-old woman with chronic schizophrenia was admitted to our department. She was diagnosed with schizophrenia at age 28. She had auditory hallucinations with voices conversing with each other and persecutory delusions but did not have mood symptoms. After brief admission at age 48, her condition was stable on thioridazine 40 mg/day and sulpiride 200 mg/day. However, at age 61, she noted the resting tremor of her left arm. She discontinued all antipsychotics for several years. But, thereafter, she experienced resting tremor of the right extremities, rigidity and postural instability. At age 69, she was diagnosed as having IPD and L-dopa/carbidopa was commenced. The treatment improved parkinsonism but exacerbated her psychosis. In addition she complained of various side-effects such as nausea and consequently discontinued it after 3 months. On admission, she had no obvious cognitive deficits (the Mini-Mental State Examination = 28/30). The results of laboratory tests and the findings of cranial magnetic resonance were normal. In 123I-metaiodobenzylguanidine myocardial scintigraphy, the average count per pixel in heart to mediastinum (H/M) ratio was decreased [H/M (early) = 1.854, H/M (late) = 1.350]. Her score on the Brief Psychiatric Rating Scale (BPRS) was 79, her stage on the Hoehn–Yahr scale was IV, and her activities-of-daily-living (ADL) rating on the Barthel index was 35. However, after she started taking aripiprazole 6 mg/day, we sometimes saw her walking by herself. Therefore, we gradually increased aripiprazole over 4 weeks to 18 mg/day. Then, her psychosis gradually improved and she wanted to be more mobile. She underwent physical therapy with successful discharge after 3 months. Her psychotic symptoms, motor function and ADL all improved without antiparkinsonian medications (BPRS = 37, Hoehn–Yahr stage = III, Barthel index = 65). She continues to do well on aripiprazole 6 months post-discharge. The number of schizophrenic patients with comorbid IPD will increase in aging patients with schizophrenia. This case suggests that aripiprazole may be useful in treating such patients (especially when L-dopa cannot be administered due to its side-effects) because aripiprazole, a dopamine D2 partial agonist, theoretically may improve hypodopaminergic activity in the nigrostriatal pathway in patients with IPD. In addition, the present patient was able to undergo physical therapy safely because aripiprazole rarely induces sedation and orthostatic hypotension due to extremely weak antagonism at α1 and H1 receptors. However, several case reports of aripiprazole in patients with psychosis associated with IPD indicate that aripiprazole worsens motor function,3, 4 partly because aripiprazole appears to bind to D2 receptors by competing with dopamine replenished by L-dopa because the binding affinity to dopamine D2 receptors of aripiprazole is higher than that of dopamine.5 It is necessary to note this when administering aripiprazole with L-dopa.