#Alzheimer #MS #Parkinson #ALS #VitaminD
Neurodegenerative diseases such as multiple
sclerosis (MS), Alzheimer’s disease (AD), Parkinson’s disease (PD), and
amyotrophic lateral sclerosis (ALS) represent a major global public health
challenge. Their
prevalence is steadily increasing, notably due to demographic
aging. These conditions are characterized by a
progressive, irreversible, and
often multifocal loss of neurological functions, leading to cognitive, motor,
sensory, or respiratory deficits depending on the disease.
Current treatments may alleviate certain
symptoms or slow the disease’s course, but they do not stop neurodegeneration.
Their effectiveness remains limited, varies between patients, and is often
accompanied by
side effects. Moreover, the lack of reliable biomarkers
complicates personalized care. These limitations highlight the
urgent need for
new approaches, more specifically targeted at the root causes of the disease.
In this context, interest in modifiable
environmental factors, such as
vitamin D, has grown significantly. Vitamin D
has been shown to play a key role in
immunomodulation,
neuroprotection, and
cellular regulation through its nuclear receptor (VDR), which is present in
many regions of the central nervous system. Its potential role in
preventing or
slowing neurodegenerative processes makes it a strong candidate for risk
modulation strategies or therapeutic adjuvants.
This study was initiated to assess the
potential role of vitamin D in the progression of MS, AD, PD, and ALS. The
objective is to better understand the underlying mechanisms, to take stock of
the current state of clinical knowledge, and to identify the gaps that need to
be filled for future integration into personalized therapeutic strategies.
Less sunlight, more neurons at risk?
In
multiple sclerosis (MS), numerous
observational studies show an association between low vitamin D levels and an
increased risk of onset or relapse. Immunomodulatory mechanisms are involved.
Vitamin D inhibits pro-inflammatory Th1 and Th17 responses while promoting
regulatory T cells. Some data suggest that higher intakes could reduce the
frequency of relapses and slow the progression of disability.
Read next: Progressive MS: could the placenta pave the way?
In
Alzheimer’s disease (AD), experimental data
are also encouraging. Vitamin D appears to play a role in beta-amyloid
clearance, protection against oxidative stress, and improvement of synaptic
plasticity. These effects are mediated by the expression of VDR in the
hippocampus, a key region for memory. However, clinical trials conducted so far
have produced variable results, often limited by methodological biases and
small sample sizes.
Read next: Genes and Alzheimer’s: the key to the mystery?
In
Parkinson’s disease (PD), vitamin D may
exert a neuroprotective effect on dopaminergic neurons in the substantia nigra.
It appears to reduce neuroinflammation, improve motor function in animal
models, and its deficiency is frequently observed in patients with Parkinson’s.
Although some studies suggest a link between deficiency and clinical worsening,
the evidence remains insufficient for concrete therapeutic recommendations.
Read next: MoCA boosted, brain relieved!
Finally, in
amyotrophic lateral sclerosis
(ALS), the literature is more limited but nonetheless suggestive. Several
studies have observed lower serum levels of vitamin D in affected patients,
sometimes associated with faster disease progression or reduced survival.
Vitamin D may act by modulating oxidative stress, regulating intracellular
calcium, and providing protective effects on motor neurons. Preclinical studies
have shown functional improvement in ALS mouse models treated with vitamin D.
However, clinical trials remain rare, with preliminary results needing
confirmation in larger and better-controlled cohorts.
Read next: ALS: exercise on prescription?
Vitamin D: a path still to be validated
Neurodegenerative diseases are characterized by
a progressive, irreversible, and often multifocal loss of neurons in the
central nervous system. This degeneration leads to
major functional
impairment—cognitive, motor, or sensory—with a profound impact on patients’
quality of life. In a therapeutic context still largely limited to symptom
management, where curative interventions are lacking, identifying modifiable
environmental factors that can influence the disease’s course has become a
major objective.
Beyond its classic role in calcium homeostasis,
vitamin D appears to be a
potential modulator of neuroinflammation, neuronal
plasticity, and brain aging. This review confirms that
chronic deficiency could
contribute to the progression of diseases like MS, Alzheimer’s, or Parkinson’s
through immune and neurotoxic mechanisms.
However, available data remain fragmented,
particularly for Alzheimer’s and Parkinson’s, and the effects of
supplementation are still debated. Randomized controlled trials are few, often
small in scale, and marked by methodological heterogeneity. More rigorous
research is needed to clarify optimal dosages, target populations, and relevant
therapeutic windows. The integration of vitamin D into preventive or
therapeutic strategies for neurodegenerative diseases must rely on robust data,
but this avenue deserves increased attention.
Read next: Vitamin D deficiency: a risk for the mind?
