Subtle imitation behaviour in convenience samples of normal, demented, and currently depressed elderly subjects

The clinical significance of imitation behaviour (IB) is unclear. The aim of this study was to investigate the prevalence of subtle naïve and obstinate IB in convenience samples of normal elderly, demented, and depressed subjects.

Subtle IB was assessed using a protocol constructed ad hoc in 146 patients, consecutively referred to a memory clinic having received an ICD-10 diagnosis of either dementia or depression, and in 241 healthy subjects. The prevalence of IB in the three groups was determined and the association with possible demographic, cognitive, and non-cognitive variables analysed.

Subtle naïve IB was frequent in the elderly with dementia, intermediate in the depressed, and rare in the normal elderly except that the latter frequently stretched out their arms. Obstinate IB never occurred in the normal elderly. IB was predicted by none of the variables used.

The groups included were convenience samples with the depressed being a small group precluding further distinction of depressive subtypes.

Although naïve IB is a frequent clinical feature in the demented, it also accompanies depressive disorders in the elderly. It can be observed as context-specific IB in the normal elderly. Obstinate IB does not occur in the normal elderly.