The effectiveness of Tai Chi for short-term cognitive function improvement in the early stages of dementia in the elderly: a systematic literature review

Figures & data

Figure 1 PRISMA diagram.

Table 1 Summary of included studies

Author/Year/Country	Study Design	Participants	Type, frequency, and duration of intervention	Cognitive outcomes/Measurements^a	Results related to cognitive measures
Chan et al 2016^Citation21 China	RCT	52 participants with MCI (determined by an MMSE score between 13–26) Mean age =81 Community-dwelling I/C =27/25	Intervention group: TC Qiqong (group class) 60 minutes, 2 times/week X 2 months Control group: health talk group in community center 1 time/week X 2 months	(1) Global cognitive function: MMSE; (2) Awareness of memory deficits: MIC; Outcomes measured at baseline, after 2 months and after 6 months,	No significant difference noted in MMSE score and MIC score between both groups (T1: p=0.394; T2: p=0.219).
Chang et al 2011^Citation19 United States	PNCT	11 participants with MCI (determined by 15≤ MMSE score ≤27; DSC ≤6; DS ≤6; Stroop Color and Word test or HVLT-R score ≤39) Mean age =85 Community-Dwelling	Intervention group: TC sun style for arthritis (group class) 20–40 minutes, 2 times/week X 15 weeks	(1) Global cognitive function: MMSE; (2) Working memory: DSC & DS; (3) Attention: ST-color-word; (4) Verbal learning and memory: HVLT-R; Outcomes measured at baseline and after 15 weeks.	At 15 weeks, no significant pre-post differences in MMSE score (p=0.22), DSC (p=0.32), DS (p=1.08), Stroop Color and Word Test (p=0.4) and HVLT-R (p=0.36). At 15 weeks, significant difference in MMSE score in elders who participated in 24–29 sessions versus those who only went to 4 or less sessions (p<0.05) and DSC (p<0.05).
Cheng et al 2014^Citation26 China	RCT	110 participants with MCI or early AD (determined by MMSE score between 10–24; CDR ≥0.5) Mean age =82 Institutionalized I/C =39/35	Intervention group: TC 12-form Yang Style or Mahjong (group class) 60 minutes, 3 times/week X 12 weeks Control group: handicraft (frequency and duration: idem)	(1) Global cognitive function: MMSE; (2) Working memory: DSF, DSB & 15-word immediate recall; (3) Episodic memory: 15-word 30 min. delayed recall; (4) Semantic memory: categorical fluency; Outcomes measured at baseline, week 12, 24 and 36.	At 24 weeks, significant difference in MMSE score (3.7 pts.) between I group (+1.5 pts.) and C group (−2.7 pts.) (95%CI: 1.4–6.0; d=0.40). Significant difference in DSF score between groups favoring I group over C group (0.98; 95%CI: 0.12–1.84; d =0.25). At all time, no significant difference between groups in DSB, 15-word immediate & 30 min. delayed recall and categorical fluency.
Deschamps et al 2009^Citation22 France	RCT	52 participants with mild to moderate cognitive impairment Mean age =81 Institutionalized 2 interventions groups: TC: n=26 CA: n=26	TC intervention group: Adapted TC Yang Style (group class) 30 minutes, 4 times/week X 24 weeks CA intervention group: Adapted physical group activity and education on health 30–40 minutes, 2 times/week X 24 weeks	(1) Global cognitive function: MMSE; Outcome measured at baseline and after 24 weeks.	At 24 weeks, TC group’s MMSE score remained stable (pre-test: 19.4±7.4; post-test: 21.1±6.4; p=0.6). No significant difference in score between both intervention groups (p=0.8).
Kasai et al 2010^Citation20 Brazil	NRCT	26 participants (elderly women) with MCI Mean age =74 Community-Dwelling I/C =13/13	Intervention group: TC Chuan Yang Style (group class) and recommendation to also practice at home 60 minutes, 2 times/week X 6 months Control group: no intervention	(1) Self-perception of memory: SMC; (2) Memory: RBMT; (3) Working memory: DSF; (4) Concentration capacity: DSB; Outcomes measured at baseline, after 3 months and after 6 months.	At 6 months, significant drop in memory complaints in I group compared to C group (p=0.023). At 6 months significant increase in RBMT score in I group compared to C group (p=0.007). At 6 months, significant difference for DSF in I group compared to C group (p=0.031). But no significant difference in DSB score between the 2 groups (p=0.164).
Lam et al 2014^Citation5 China	RCT	238 participants with amnestic MCI or CDR =0.5 Mean age =78 Community-dwelling I/C =96/169	Intervention group: TC (4–6 weeks center-based and 46–48 weeks home-based training with DVD of TC program + monthly refresher). 30 minutes, 3 times/week X 1 year Control group: Stretching and relaxation exercises by PT &OT	(1) Global severity of cognitive impairment: CDR; (2) Global cognitive function: ADAS-COG & MMSE; (3) Working memory: DSB; (4) Episodic memory: 10-min. delayed recall; (5) Semantic memory: Category verbal fluency tests; Outcomes measured at baseline, after 2 months and after 12 months.	At 1 year, I group had better cognitive preservation than C group: 4/92 (4.3%) [I] VS 28/169 (16.6%) [C] progressed to dementia (odds ratio [OR] =0.28; 95%CI=0.05–0.92; p=0.064). Significant difference in score favoring I group for CDR score (p=0.038; 95%CI =0.63–0.99). At 1 year, both groups improve in ADAS-COG, DSB, Delayed recall test and category verbal fluency but no significant difference between groups was noted (p>0.05). No significant change in MMSE score in both groups (95%CI=−0.62–1.42; p=0.44).
Li et al 2014^Citation23 United States	NRCT	46 participants with MCI (determined by 20≤ MMSE score ≤25) Mean age =76 Community-dwelling I/C =22/24	Intervention group: Enhanced TC Chuan (group class) 60 minutes, 2 times/week X 14 weeks Control group: no intervention	Global cognitive function: MMSE; Outcome measured at baseline and after 14 weeks.	At 14 weeks, I group showed significant improvement on MMSE (mean =2.26, p<0.001) compared to C group (mean =0.63, p=0.08).
Sungkarat et al 2017^Citation25 Thailand	RCT	66 participants with MCI (meeting Peterson’s criteria for diagnosing amnestic multiple-domain MCI) Mean age =68 Community-dwelling I/C =33/33	Intervention group: TC 10-forms style (3 weeks center-based & 12 weeks home-based with DVD of TC program) 50 minutes, 3 times/week X 15 weeks Control group: education group on cognitive impairment	(1) Episodic memory: Logical Memory – delayed recall; (2) Visuospatial ability: Block Design; (3) Executive function: DSF, DSB & TMT-B; Outcomes measured at baseline and after 15 weeks.	At 15 weeks, scores were significantly better in I group compared to C group for the Logical Memory – delayed recall (p=0.006), Block Design (p=0.01) and Trail Making Test – Part B-A (p=0.005). No significant difference between groups for DSF and DSB (p=0.43).
Tsai et al 2013^Citation24 United States	RCT	55 participants with MCI (determined by 18≤ MMSE score ≤28) Mean age =79 Community-dwelling I/C =28/27	Intervention group: TC Sun Style (group class) 20–40 minutes, 3 times/week X 20 weeks Control group: health and cultural information class (frequency and duration: idem)	Global cognitive function: MMSE; Outcome measured at baseline, week 5, 9, 13, 17 and 21.	At 21 weeks, significant improvement in MMSE score only in I group (p=0.003 [I] vs p=0.082 [C]). No significant change in difference between the 2 groups over time (p=0.223).

Notes: ^aCognitive outcomes and measurements used by the authors.

Abbreviations: ADAS-COG, Alzheimer’s Disease Assessment Scale – Cognitive; AMD, Adjusted Mean Difference; C, Control Group; CA, Cognition-Action program; CDR, Clinical Dementia Rating; DAD, Disability Assessment for Dementia; DS, Digit Span; DSB, Digit Span Backward; DSC, Digit Symbol Coding; DSF: Digit Span Forward; HVLT-R, Hopkins Verbal Learning test – Revised; I, Intervention Group; MCI, Mild Cognitive Impairment; MIC, Memory Inventory for Chinese Questionnaire; MMSE, Mini Mental Status Exam; NPI, Neuropsychiatric Inventory; NRCT, Non-Randomize Control Trial; OT, Occupational Therapy; PNCT, Prospective Non Controlled Trial; PT, Physical Therapist; RCT, Randomize Controlled Trial; RBMT, Rivermead Behavioural Memory Test; SMC, Subjective Memory Complaints Scale; ST-color-word, Stroop color and Word test; TC, Tai Chi; TMT-B, Trail Making Test – Part B.

Table 2 Summary of study quality and risk of bias

Study	Reporting (scored out of 11)	External validity (scored out of 3)	Internal validity – Bias^b (scored out of 7)	Interval validity – confounding (selection bias, scored out of 6)	Total score (out of 28)
Chan et al^Citation21	10	2	5	5	22
Chang et al^Citation19,^a	7/9	0	4/6	0/1	15.6^a
Cheng et al^Citation26	10	3	5	5	24
Deschamps et al^Citation22	9	2	5	5	21
Kasai et al^Citation20	7	0	5	2	14
Lam at al^Citation5	7	2	6	5	20
Li et al^Citation23	11	1	4	3	19
Sungkarat et al^Citation25	11	2	6	5	25
Tsai et al^Citation24	10	2	5	5	22

Notes: ^aThis article was a prospective non-controlled trial for which the scores and total score were adjusted. ^bThe main outcomes considered during the evaluation of quality are only those related to cognition.

Abbreviations: ADAS-Cog, Alzheimer’s Disease Assessment Scale; CAMDEX, Cambridge Examination for Mental Disorders of the Elderly; CDR, Clinical Dementia Rating; CINAHL, Cumulative Index to Nursing and Allied Health Literature; DSB, Digit Span Backward; DSC, Digit Symbol Coding; DSF, Digit Span Forward; EMBASE, Excerpta Medica Database; HVLT-R, Hopkins Verbal Learning Test – Revised; MIC, Memory Inventory for Chinese Questionnaire; MCI, Mild cognitive disorder; MMSE, Mini-Mental State Examination; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses; SMC, Subjective Memory Complaints Scale; PRISMA, Systematic Reviews and Meta-Analyses; TMT-B, Trail Making Test – Part B; WAIS, Wechsler Adult Intelligence Scale.

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