Stereotypic behaviors in degenerative dementias

Stereotypies are simple or complex involuntary/unvoluntary behaviors, common in fronto-temporal dementia (FTD), but not studied in other types of degenerative dementias. The aim was to investigate stereotypy frequency and type in patients with FTD, Alzheimer’s disease (AD), progressive supranuclear palsy (PSP) and Parkinson’s disease with dementia (PDD) in a multicenter observational study; and to investigate the relation of stereotypies to cognitive, behavioral and motor impairment. One hundred fifty-five consecutive outpatients (45 AD, 40 FTD, 35 PSP and 35 PDD) were studied in four hospitals in northern Italy. Stereotypies were examined by the five-domain Stereotypy Rating Inventory. Cognition was examined by the Mini Mental State and Frontal Assessment Battery, neuropsychiatric symptoms by the Neuropsychiatric Inventory, and motor impairment and invalidity by the Unified Parkinson’s Disease Rating Scale part III, and activities of daily living. Stereotypies were present in all groups. FTD and PDD had the greatest frequency of one-domain stereotypies; FTD also had the greatest frequency of two-or-more domain stereotypies; movement stereotypies were the most common stereotypies in all groups. AD patients had fewer stereotypies than the other groups. Stereotypies are not exclusive to FTD, but are also fairly common in PSP and PDD, though less so in AD. Stereotypies may be underpinned by dysfunctional striato-frontal circuits, known to be damaged in PSP and PDD, as well as FTD.