Depression and sarcopenia-related traits: A Mendelian randomization study

Table 1 Studies and datasets adopted in the Mendelian randomization analyses

Trait	Data source	Sample size, cases/controls	Ancestry
Depression	UK Biobank1	127552/233763	European
	23andMe_307K2	75607/231747
	PGC_139K3	43204/95680
	Replication	474574/1032579
Appendicular lean mass	UK Biobank1	450243	European
Hand grip strength, exposures	UK Biobank1	Approximately 360000	European
Hand grip strength, outcomes	UK Biobank1	334925	European

¹UK biobank: (1) The broad definition of depression was used in the UK Biobank. Measured in a variety of ways, as follows: Have you ever seen a general practitioner for nerves, anxiety, tension or depression? and have you ever seen a psychiatrist for nerves, anxiety, tension or depression? and (2) Does not include the participants who were identified with bipolar disorder, schizophrenia, or personality disorder using self-declared data as well as prescriptions for antipsychotic medications.

²23andMe_307k: (1) The data were derived from the genome-wide association study results from the 23andMe Interactive Discovery projects; and (2) Depression was defined based on responses to web-based surveys, with individuals that self- reported as having received a clinical diagnosis or treatment for depression classified as cases.

³PGC_139k: (1) The PGC_139k cohort was obtained from the meta-analysis of major depressive disorder utilizing European-ancestry PGC cohorts with the 23andMe_307k and the previous UK Biobank cohorts removed; and (2) Depression was defined based on structured diagnostic interviews, or electronic medical records, with individuals that self-reported as having received a clinical diagnosis or treatment for depression.

Table 2 Results of potential pleiotropy and heterogeneity assessments in the bidirectional analyses

Parameter	Cochran's Q	P for Cochran's Q	Intercept	P for intercept
Outcome
Appendicular lean mass	911.568	< 0.001	-0.002	0.602
Left hand grip strength	409.92	0.004	0.002	0.486
Right hand grip strength	379.511	< 0.001	0.002	0.243
Exposure
Appendicular lean mass	1401.776	< 0.001	0.001	0.953
Hand grip strength	306.463	< 0.001	0.003	0.887