Interaction of bovine glutamate dehydrogenase with isoquinoline alkaloids

Possible relation of atypical parkinsonism in the French West Indies with consumption of tropical plants: a case-control study. Caribbean Parkinsonism Study Group

BACKGROUND

In Europe and North America, Parkinson's disease is the major form of parkinsonism; less than 4% of cases are progressive supranuclear palsy (PSP) and about 20% are atypical parkinsonism. The distribution of these subgroups is different in the French West Indies. We aimed to define the clinical and demographic specificity of these disorders in Guadeloupe and to investigate a postulated link with consumption of herbal tea and fruits from the Annonaceae family (Annona muricata and Annona squamosa), which contain neurotoxic benzyltetrahydroisoquinoline alkaloids.

METHODS

Between September, 1996, and August, 1998, 87 consecutive patients with parkinsonism were referred to the single neurological department in Guadeloupe. After detailed clinical, neurophysiological, cognitive, and neuroradiological assessment, they were classified by generally accepted criteria as having Parkinson's disease, PSP, or atypical parkinsonism. We compared the amount of tropical fruits and herbal tea consumed by the various parkinsonian subgroups and by frequency-matched controls (patients with benign symptoms and no neurodegenerative disease).

FINDINGS

Of the 87 patients, 22 had Parkinson's disease, 31 had PSP, 30 had atypical parkinsonism, and four had atypical parkinsonism associated with motor neuron disease, 44 of the patients with PSP or atypical parkinsonism were male. The patients with atypical parkinsonism had symmetrical rigidity and bradykinesia, and no levodopa peak-dose dyskinesias. Patients with PSP differed from those with atypical parkinsonism because they had supranuclear vertical down-gaze palsy, severe gait and balance problems, and frontal-lobe syndrome. 29 patients with PSP reported regular consumption of pawpaw fruit, and 26 drank herbal tea. 30 patients with atypical parkinsonism reported regular consumption of pawpaw fruit, and 24 drank herbal tea. Both of these groups consumed significantly more fruit and herbal tea than patients with Parkinson's disease (fruit: odds ratio 23.6; herbal tea: 28.2); and controls (fruit: 20.7; herbal tea: 6.48).

INTERPRETATION

Our study confirms the over-representation of atypical parkinsonism and PSP in patients with parkinsonism in the French West Indies. Chronic exposure to neurotoxic alkaloids could be an important aetiological factor because these compounds induce parkinsonism in animals. A larger epidemiological study, to clarify the link between these fruits with atypical parkinsonism and PSP, is proposed.