Minor hallucinations may predate Parkinson motor symptoms

By Eleanor McDermid, Senior medwireNews Reporter

About four in 10 patients with untreated Parkinson’s disease (PD) experience minor hallucinations, research shows.

“The description of visual illusions and minor hallucinations in early PD is not novel”, say Jaime Kulisevsky (Sant Pau Hospital, Barcelona, Spain) and co-researchers.

“However, a novel finding of this study is the observation that minor hallucinatory phenomena may appear not only before starting dopaminergic treatment, but long in advance of the onset of parkinsonian motor symptoms.”

All patients said their hallucinations began before diagnosis and treatment with dopaminergic drugs. And a third of those with hallucinations reported that these predated their motor symptoms, beginning between 7 months and 8 years before onset.

In all, 21 (42%) of the 50 PD patients in the study reported minor hallucinations within the preceding 3 months, compared with just 5% of 100 healthy controls of similar age. The PD patients were aged an average of 68.8 years and were untreated, with an average disease duration of 19.5 months.

The team assessed patients and controls with the Hallucinations and Psychosis item of the Unified Parkinson’s Disease Rating Scale, followed by a semistructured interview to further characterise the hallucinations.

Among patients with hallucinations, 28.6% had isolated passage hallucinations (fleeting passage of a shadow, person, animal or object), 14.3% had isolated presence hallucinations and 57.1% had both. Patients with both types had them more than once a week, whereas those with just one type had them less often but at least once a month.

Seven patients also had visual illusions, two had isolated visual illusions, two had olfactory hallucinations and one had auditory hallucinations.

Kulisevsky et al note in Movement Disorders that most previous studies reporting much lower rates of hallucinations assessed patients only for structured hallucinations; these occurred in 10% of patients in their study.

Patient characteristics were generally similar between those with and without hallucinations, except that REM sleep behaviour disorder was significantly more common in the former than the latter, at 38.1% versus 10.3%.

The researchers conclude that “epidemiological studies in larger populations of healthy controls and subjects at risk of developing PD will further clarify whether minor hallucinations constitute a confident premotor marker of PD.”

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