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Table 8 Main findings and directions for future TAND research

From: The research landscape of tuberous sclerosis complex–associated neuropsychiatric disorders (TAND)—a comprehensive scoping review

Research question

Main findings

Directions for future research

1. TAND research across years

The number of TAND studies has increased over time, particularly since the term TAND was coined

Systematic reviews of each cluster should be conducted to capture TAND research that may have been missed

2. TAND research location

TAND research is predominantly conducted in HICs, the majority of HIC-led TAND research occurs in the USA and the UK

More research is needed particularly in South American, Middle Eastern, African, South-East Asia and Western Pacific countries

TAND research is only evident in some LMICs due to representation from larger HIC-led multisite studies (e.g. Argentina, Mexico, Romania)

More TAND-focused research is needed that originates from LMICs reflecting specific cultural contexts, as opposed to research that only includes LMICs as part of larger multisite studies

3. Age distribution

The majority of human TAND research involves school-age and adolescent samples, with fewer studies including infant (0–3 years) or older adult samples (60 years and over)

Research that specifically focuses on the presentation of TAND across the lifespan and longitudinal research that investigates changes in TAND across developmental stages are needed

4. Study quality

Most case and cohort studies provide epilepsy and intellectual ability information but TSC genetic confirmation in studies is relatively low

TAND researchers should be encouraged to include data on seizures, intellectual ability and TSC genotype where possible

The majority of TAND cohort studies involve fewer than 50 participants

Large-scale, coordinated cohort studies involving multisite international collaboration should be considered, except where specific research questions warrant small samples

Animal studies and case studies are rated as high or relatively high quality; however, there is considerable variability in the quality of cohort studies, perhaps as a consequence of the quality appraisal tool used

Development of a scoping review quality appraisal tool will be beneficial to aid in the interpretation of study quality that allows for cross-comparison between different study designs

5. TAND levels

Animal studies largely report on the behavioural level of TAND

More contemporary animal research is needed that explores the neuropsychological level of TAND

Case studies and cohort studies largely report on behavioural and intellectual TAND levels

In human studies, research is needed that focuses on the academic, neuropsychological and psychosocial levels of TAND

6. Research methods and measures

Animal studies utilise behavioural protocols and neuroimaging techniques

More TSC animal model research is needed that specifically utilises behavioural protocols that are relevant to TAND

Case studies largely employ medical record reviews neuroimaging and physiological examinations, but rarely utilise standardised research assessments

TAND case studies would benefit from the inclusion of standardised assessments where possible and description of assessments completed as part of a clinical evaluation

Cohort studies utilise IQ assessments and diagnostic research measures of autism

More direct behavioural assessments and behavioural observations in TAND research is needed, as well as a need to outline which specific diagnostic measures have been utilised when reporting TAND information based on psychological evaluation

As a recently published measure, the TAND Checklist is rarely used as an assessment tool in human research

Human studies would benefit from the inclusion of TAND Checklist reporting where applicable

7. Quantitative and qualitative research

There are relatively few qualitative cohort studies

Qualitative research will be useful to refine the phenomenology of TAND behaviours that are not well-characterised in the existing literature

The few qualitative studies that exist largely explore the psychosocial level

More qualititative research is needed that explores the under-researched areas of TAND

The majority of quantitative cohort studies are descriptive as they do not utilise contrast or control groups

TAND cohort studies would benefit from the utilisation of appropriate control and contrast groups to determine TSC-specific manifestations of behaviours

8. Interventions

There are very few published intervention cohort studies, with a notable absence of any non-pharmacological intervention studies

Intervention studies are needed that take into account TAND outcomes, particularly exploring the effectiveness of non-pharamacological interventions in relation to TAND

9. Remote technologies

Only a small minority of cohort studies have employed remote methods of data collection, those that do largely explore the psychosocial level

Studies utilising remote technologies (e.g. mobile applications, video conferencing, online surveys) may help address TAND knowledge gaps and increase LMIC and population-based research

10. TAND clusters

A number of TAND clusters are under-researched in animal studies

More TSC animal models are needed that explore the dysregulated behaviour, overactive/impulsive and eat/sleep clusters

Across human studies, the scholastic cluster is relatively under-researched

TAND clusters that are under-researched may be difficult to assess or quantify, and efforts should be made to evaluate existing assessments and tools to determine their utility in TSC cohorts

The autism spectrum disorder–like cluster is the most widely researched across all three study types

Human studies would benefit from TAND-specific research that explores under-researched clusters, specifically the scholastic and eat/sleep clusters in TSC cohorts