Study Indicates ADHD By Itself Has Negligible Effect on Risk of Type 2 Diabetes

Noting that “evidence on the association between ADHD and a physical condition associated with obesity, namely type 2 diabetes mellitus (T2D), is sparse and has not been meta-analysed yet,” a European study team performed a systematic search of the peer-reviewed medical literature followed by a meta-analysis, and then a nationwide population study.

Unlike type 1 diabetes, which is an auto-immune disease, type 2 diabetes is believed to be primarily related to lifestyle, associated with insufficient exercise, overconsumption of highly processed foods, and especially with large amounts of refined sugar. This leads to insulin resistance and excessively high blood glucose levels that damage the body and greatly lower life expectancy.

Because difficulty with impulse control is a symptom of ADHD, one might hypothesize that individuals with ADHD would be more likely to develop type-2 diabetes. 

The meta-analysis of four cohort studies encompassing more than 5.7 million persons of all ages spread over three continents (in the U.S., Taiwan, and Sweden) seemed to point in that direction. It found that individuals with ADHD had more than twice the odds of developing type 2 diabetes than normally developing peers. There was no sign of publication bias, but between-study variability (heterogeneity) was moderately high.

The nationwide population study of over 4.2 million Swedish adults came up with the same result when adjusting only for sex and birth year. 

Within the Swedish cohort there were 1.3 million families with at least two full siblings. Comparisons among siblings with and without ADHD again showed those with ADHD having more than twice the odds of developing type 2 diabetes. That indicated there was little in the way of familial confounding.

However, further adjusting for education, psychiatric comorbidity, and antipsychotic drugs dropped those higher odds among those with ADHD in the overall population to negligible (13% higher) and barely significant levels. 

The drops were particularly pronounced for psychiatric comorbidities, especially anxiety, depression, and substance use disorders, all of which had equal impacts.

The authors concluded, “This study revealed a significant association between ADHD and T2D [type 2 diabetes] that was largely due to psychiatric comorbidities, in particular SUD [substance use disorders], depression, and anxiety. Our findings suggest that clinicians need to be aware of the increased risk of developing T2D in individuals with ADHD and that psychiatric comorbidities may be the main driver of this association. Appropriate identification and treatment of these psychiatric comorbidities may reduce the risk for developing T2D in ADHD, together with efforts to intervene on other modifiable T2D risk factors (e.g., unhealthy lifestyle habits and use of antipsychotics, which are common in ADHD), and to devise individual programs to increase physical activity. Considering the significant economic burden of ADHD and T2D, a better understanding of this relationship is essential for targeted interventions or prevention programs with the potential for a positive impact on both public health and the lives of persons living with ADHD.”

Miguel Garcia-Argibay, Lin Li, Ebba Du Rietz, Le Zhang, Honghui Yao, Johan Jendle, Josep A. Ramos-Quiroga, Marta Ribasés, Zheng Chang, Isabell Brikell, Samuele Cortese, Henrik Larsson, “In utero exposure to ADHD medication and long-term offspring outcomes,” Neuroscience and Biobehavioral Reviews (2023), 147:105076, https://doi.org/10.1016/j.neubiorev.2023.105076.

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Nationwide population study finds cancer survivors have much higher risk of ADHD

Nationwide Population Study Finds Cancer Survivors Have Much Higher Risk of ADHD

Thanks to improvements in cancer treatment, there is a growing population of childhood and adolescent cancer survivors (CACSs). CACSs are at an increased risk of chronic physical, psychological, and social problems because of their cancer experiences and intensive cancer treatments. These include depression, anxiety, suicidal ideation, and post-traumatic stress disorder (PTSD). 

To what extent, if at all, does this also apply to ADHD? Noting that “previous studies … have reported inconsistent findings,” a local research team took advantage of Taiwan’s mandatory single-payer National Health Insurance that covers over 99% of the island’s population. More specifically, the National Health Insurance Research Database (NHIRD) maintains data on the insured population available on formal request for study purposes.

Linking the catastrophic illness database, mental disorders database, and longitudinal health insurance database, they tracked children age younger than 10 years and adolescents aged 11-17 years who were diagnosed with any malignancy (cancer) between 2002 and 2011 with no history of major psychiatric disorders (including ADHD). Parental history of major psychiatric disorders was likewise controlled as a potential confounder.

The team identified 5,121 CACSs, which they matched one to ten with 51,210 age-, sex-, income-, and residence-matched cancer-free controls.

ADHD diagnoses were made by board-certified psychiatrists during the study follow-up period (from enrollment through 2011) based on a comprehensive clinical interview and clinical judgment. 

Cancer survivors were diagnosed with ADHD at more than six times the rate of matched controls. Survival duration made no significant difference in this outcome. 

Cancers of bone, connective tissue, skin, and breast were associated with a more than threefold increase in risk of an ADHD diagnosis. For cancers of the circulatory system, there was a more than sixfold increased risk of ADHD, and for those of the genitourinary organs, more than sevenfold increased risk. 

For brain cancer survivors, the increased risk of ADHD was more than twelvefold. That may be at least in part because the brain itself was targeted for treatment in these instances, which plausibly could cause damage resulting in psychiatric disorders.

The team concluded, “we observed a comparatively higher risk of MPDs [major psychiatric disorders] among CACSs than among controls and likewise found that such risks varied across different cancer types. Survivors of both CNS [central nervous system] and non-CNS cancers have increased risks of MPD diagnoses. Among the enrolled CACSs, ASD [autism spectrum disorder] and ADHD were associated with most types/categories of cancers. Long-term care of this vulnerable population must include psychosocial interventions for patients and their families. Physicians need to be aware of early signs of mental health problems in this high-risk subpopulation and arrange early interventions accordingly.”

February 9, 2024

Population Study Finds No ADHD- or ASD- Related Benefits From Eating Organic Food During Pregnancy

Norwegian Nationwide Population Study Finds No ADHD- or ASD- Related Benefits From Eating Organic Food During Pregnancy

Background:

Organic farming aims to protect biodiversity, promote animal welfare, and avoid using pesticides and fertilizers made from petrochemicals. Some pesticides are designed to target insects’ nervous systems but can also affect brain development and health in larger animals, including humans.

Many people believe organic food is healthier than conventionally produced food, which might be true for certain foods and health factors. But does eating organic food during pregnancy impact the chances of a child developing ADHD or autism spectrum disorder (ASD)?

In Norway, researchers can use detailed national health records to study these connections on a population-wide level, thanks to the country’s single-payer healthcare system and national registries.

Method:

The Norwegian Mother, Father, and Child Cohort Study (MoBa) invites parents to participate voluntarily and has a 41% participation rate. The study includes:

  • 114,500 children
  • 95,200 mothers
  • 75,200 fathers

For this research, a team tracked 40,707 mother-child pairs from children born between 2002 and 2009. They used questionnaires to measure how much organic food mothers consumed during pregnancy. ADHD and ASD symptoms in children were assessed using validated rating scales.

The final analysis included:

  • 40,586 pairs for ADHD symptoms
  • 40,117 pairs for ASD symptoms

The researchers adjusted for factors like maternal age, education, previous pregnancies, BMI before pregnancy, smoking and alcohol use during pregnancy, birth year and season, and the child’s sex.

Key Findings:
  • There was a weak connection between higher organic food consumption and fewer ADHD symptoms in children. However, this link disappeared when maternal ADHD symptoms were considered (31,411 pairs) or when the analysis was limited to siblings (5,534 pairs).
  • Similarly, weak associations between organic food and fewer ASD symptoms disappeared when focusing on siblings (4,367 pairs).
Conclusion:

The researchers concluded that eating organic food during pregnancy has no meaningful effect on the likelihood of a child developing ADHD or ASD. They stated, “The results do not indicate any clinically significant protective or harmful effects of eating organic food during pregnancy on symptoms of ADHD and ASD in the offspring. Based on these findings, we do not recommend any specific advice regarding intake of organic food during pregnancy.”

January 27, 2025

Meta-analysis Finds Little or No Link Between Assisted Reproductive Technologies and ADHD

Background:

Infertility affects about one in six couples worldwide. To address this, medical experts have developed Assisted Reproductive Technologies (ART), including In Vitro Fertilization (IVF) with or without Intra-Cytoplasmic Sperm Injection (ICSI).

Some research suggests that children conceived through ART might have higher rates of intellectual disabilities, cerebral palsy, cancer, and neurological issues compared to children conceived naturally. However, studies looking at a possible link between ART and ADHD have produced mixed and conflicting results.

Until now, there hasn’t been a meta-analysis examining the connection between ART and ADHD. A South Korean research team has conducted the first systematic review and meta-analysis on this topic. Their final analysis included eight studies with a total of over ten million participants, comprising six cohort studies and two cross-sectional studies.

Method:

The research focused on two types of studies:

  1. Cohort Studies: These follow two groups (one exposed to ART and one not exposed) over time to see if a specific outcome, like ADHD, occurs.
  2. Cross-Sectional Studies: These compare the prevalence of ADHD at a single point in time between those exposed to ART and those who weren’t.

Both types of studies are observational, meaning they don’t involve controlled experiments and can be influenced by confounding factors.  So they can document interesting associations, not causality.  The studie were mostly large-scale national studies and used clinical ADHD diagnoses.

Key Findings:
  • Cohort Studies: Meta-analysis of six cohort studies, involving nearly 8 million participants, found no link between ART and ADHD. However, there was high variability (heterogeneity) in the results from individual studies.
  • Cross-Sectional Studies: Meta-analysis of two cross-sectional studies, covering over 2.3 million participants, also found no link between ART and ADHD. Heterogeneity was moderate.
  • Adjustment for Confounding: A separate analysis of three studies that adjusted for confounding factors (like socioeconomic status or parental health) involved more than 7.5 million participants. It found a very small association, with ART-conceived children being 8% more likely to develop ADHD. There was no variability among these studies.
Conclusion:

The researchers concluded that while there may be a small association between ART and ADHD, the effect is minimal, and the results are influenced by differences in study designs. They advised interpreting these findings with caution, noting, “The limited effect size and inherent heterogeneity underscore the need for cautious interpretation.”

January 24, 2025

Taiwan nationwide population study documents link between ADHD and periodontitis in adolescents

Background:

Periodontitis, commonly known as gum disease, is a condition where the gums become inflamed. If untreated, it can cause the gums to pull back from the teeth, exposing their base, which may eventually lead to loose teeth or tooth loss. While this condition mostly affects adults, it’s also common among teens who don’t floss or brush their teeth properly.

Until now, only a few small studies have looked at a possible link between ADHD and gum disease. A team in Taiwan recently conducted a nationwide study to explore this connection.

Taiwan has a universal health insurance program, introduced in 1995, that provides medical care to nearly all (99.7%) residents. The Taiwan National Health Research Database collects and oversees all insurance claims, making it an excellent resource for large-scale studies.

Methods:

The researchers used the database to identify teens aged 12 to 19 with ADHD (diagnosed by a psychiatrist) who had no history of gum disease between 2001 and 2011. These teens made up the ADHD group. They matched each ADHD participant with four teens who didn’t have ADHD or gum disease, creating a control group. The groups were matched by age, gender, enrollment date, family income, place of residence, and other health conditions (like obesity, diabetes, smoking, depression, and substance use).

All diagnoses of gum disease were confirmed by board-certified dentists.

The study included:

  • 16,211 teens with ADHD
  • 162,110 matched controls
Key Findings:
  • Teens with ADHD were 2.3 times more likely to develop gum disease than those in the control group without ADHD.
  • There were no significant differences between boys and girls or among teens from different income levels (low, medium, or high).
  • ADHD medications, mainly methylphenidate, didn’t affect the likelihood of developing gum disease. This was true for both short-term and long-term users compared to non-users.
Conclusion:

The researchers concluded that teens with ADHD have a higher risk of developing gum disease later on, even after accounting for other risk factors like smoking, diabetes, and depression. They stated, “ADHD is an independent risk factor for developing periodontitis.”

January 23, 2025