PT  - JOURNAL ARTICLE
AU  - Sarah C. Lidstone
AU  - Michael Costa-Parke
AU  - Emily J. Robinson
AU  - Tommaso Ercoli
AU  - Jon Stone
ED  - ,
TI  - Functional movement disorder gender, age and phenotype study: a systematic review and individual patient meta-analysis of 4905 cases
AID  - 10.1136/jnnp-2021-328462
DP  - 2022 Jun 01
TA  - Journal of Neurology, Neurosurgery & Psychiatry
PG  - 609--616
VI  - 93
IP  - 6
4099  - http://jnnp.bmj.com/content/93/6/609.short
4100  - http://jnnp.bmj.com/content/93/6/609.full
SO  - J Neurol Neurosurg Psychiatry2022 Jun 01; 93
AB  - Functional movement disorder (FMD) is a common manifestation of functional neurological disorder presenting with diverse phenotypes such as tremor, weakness and gait disorder. Our current understanding of the basic epidemiological features of this condition is unclear. We aimed to describe and examine the relationship between age at onset, phenotype and gender in FMD in a large meta-analysis of published and unpublished individual patient cases. An electronic search of PubMed was conducted for studies from 1968 to 2019 according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Individual patient data were collected through a research network. We described the distribution of age of onset and how this varied by gender and motor phenotype. A one-stage meta-analysis was performed using multilevel mixed-effects linear regression, including random intercepts for country and data source. A total of 4905 individual cases were analysed (72.6% woman). The mean age at onset was 39.6 years (SD 16.1). Women had a significantly earlier age of onset than men (39.1 years vs 41.0 years). Mixed FMD (23.1%), tremor (21.6%) and weakness (18.1%) were the most common phenotypes. Compared with tremor (40.7 years), the mean ages at onset of dystonia (34.5 years) and weakness (36.4 years) were significantly younger, while gait disorders (43.2 years) had a significantly later age at onset. The interaction between gender and phenotype was not significant. FMD peaks in midlife with varying effects of gender on age at onset and phenotype. The data gives some support to ‘lumping’ FMD as a unitary disorder but also highlights the value in ‘splitting’ into individual phenotypes where relevant.Data are available upon reasonable request.