OBJECTIVE:The authors describe and quantify the neuropsychiatric symptoms present in a cohort of males with the fragile X mental retardation 1 (FMR1) premutation allele who have developed fragile X-associated tremor/ataxia syndrome (FXTAS). METHOD:Fourteen male carriers of the FMR1 premutation who had clinical manifestations of the FXTAS syndrome and 14 age- and education-matched controls were assessed with the Neuropsychiatric Inventory (NPI), formal cognitive testing, and genetic analysis. RESULTS:Males with FXTAS had significantly higher total NPI scores (p < .004) and significantly higher scores on the agitation/aggression (p < .004), depression (p < .004), apathy (p < .004), disinhibition (p < .004), and irritability (p < .004) scales, compared with controls. Cognitive performances on the Mini-Mental State Examination did not correlate with severity of symptoms on the NPI. CONCLUSIONS:The neuropsychiatric manifestations of FXTAS, based on this preliminary report, appear to cluster as a fronto-subcortical dementia. Clinicians encountering patients with clinical dementia with motor symptoms suggesting FXTAS should consider genetic testing to determine whether the patient's dementia syndrome is secondary to a fragile X premutation carrier status.