Shared Individual Formulation Therapy (SIFT): an open-label trial of a new therapy accommodating patient heterogeneity in functional neurological disorder.

Abstract

Functional Neurological Disorder (FND) is a complex neuropsychiatric condition with a multifactorial aetiology. The heterogeneity of patients with FND is rarely considered in psychotherapy trials, which may contribute to variable outcomes. Shared Individual Formulation Therapy (SIFT) is a new, brief (four session) psychotherapy that aims to accommodate heterogeneity by providing a personalised, trans-theoretical formulation of the person's difficulties and accompanying management plan. An open-label, prospective trial of outpatient SIFT for adults with FND was conducted, using health-related quality of life (SF-12) as the principal outcome measure, with secondary measures of mental health, dissociation, health care use and attitude to the FND diagnosis. Measures were collected at baseline, end of treatment and 6- and 12-month follow-ups. Twenty-nine participants with various FND symptoms enrolled. Twenty-four completed all four sessions and 25 completed follow-up measures at 12 months. SF-12 scores improved significantly at end of treatment and were sustained throughout follow-up with moderate effect sizes (0.39-0.47; all p < 0.001). Most secondary outcomes also improved significantly at all time points. The intervention was highly acceptable and tolerable to patients and perceived as beneficial. This trial provides preliminary evidence for initial and sustained benefit from SIFT for adults with FND. Further study is needed to validate these findings.