Previous research on self-informant reports in assessing personality disorders (PDs) has been mainly focused on adults, leaving older adults under-studied. We examined self-informant agreement in PD screening among older adults (≥60 years) using the Gerontological Personality disorders Scale (GPS). Potential differences such as who reports more personality pathology on a PD screener (i.e., GPS), item accessibility and the effect of relational aspects were studied as well. Data of 326 older adult-informant dyads, of which the older adults were sampled from five general practices in the Netherlands, were used. Results indicate that self-informant agreement ranged from r = 0.26-0.73, with lower concordance on the GPS-subscale measuring intrapersonal aspects of personality pathology. Informants were more sensitive to habitual pathological personality features than older adults. Two GPS items showed differential item functioning across self- and informant-report. Of relational aspects, only congeniality affected the GPS-iv scores; lower ratings on congeniality were associated with higher GPS-iv scores (i.e., higher reporting of personality problems).
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