The unrelated communication interlude (UCI)--an automatic behavior phenomenon in Parkinson's disease.

We report on 8 patients with Parkinson's disease (PD) who experienced suddenly episodes of speech unrelated to the topic of conversation or wrote sentences unrelated to the context. During these episodes and later, unless pointed out, patients were unaware of the behavior. We called this phenomenon Unrelated Communication Interlude (UCI). All patients were male; half of them with impulse control disorders (punding, hypersexuality, or pathological gambling). Four patients reported sleepiness when the episodes of UCI occurred. There were no significant differences in age at examination, age of onset of PD, and neuropsychological tests score (Mini-Mental State Examination, Frontal Assessment Battery, and Beck Depression Inventory) between patients with UCI and those without. To our knowledge, this is the first reported phenomena of such abnormal behavior in Parkinson's disease. UCI was considered as automatic behavior similar to that seen in narcolepsy and excessive daytime sleepiness. UCI might be occurring in relation to excessive daytime sleepiness in PD.