Rewriting Your Cognitive Future: Intelligence Across the Lifespan

Everything Exists on a Gradient

Almost everything in biology and pathology exists on a spectrum—there are no sharp lines, only thresholds we've drawn for convenience.

Someone is diagnosed with depression only if symptoms persist for over two weeks. One day less? Nothing to see here. They must meet three out of five criteria. Two and a half? Doesn't count.

Someone must score below a certain threshold on the MMSE (Mini-Mental State Examination) to fit criteria for mild cognitive impairment. Anything above that line is considered "normal"—even if they're noticeably less sharp than they were at 25.

This is how we talk about cognitive health: arbitrary lines on a continuous spectrum. But the underlying reality? The decline begins much earlier than we admit, and what we call "normal aging" is just the slow march along that gradient.

The Default Trajectory: A Story of Two Intelligences

Here's what happens to most people:

Around age 25, fluid intelligence—your ability to reason, solve novel problems, and think flexibly—reaches its peak. From there, it begins a gradual decline.

For the first few decades, this decline is relatively slow and subtle. You might not notice it at all because something else is happening simultaneously: crystallized intelligence is steadily increasing. This is your accumulated knowledge, wisdom, life experience, and intuition. Every book you read, every problem you solve, every conversation you have adds to this growing repository.

The result? For most of your adult life, the slow loss in one type of intelligence is offset by steady gains in another. Your total cognitive capacity feels stable, even if the composition is shifting.

But this equilibrium doesn't last forever.

Eventually, crystallized intelligence gains plateau—there's only so much new knowledge and wisdom we naturally accumulate from daily life. Meanwhile, the decline in fluid intelligence continues and often accelerates. The offset disappears, and the gradient becomes visible: what was subclinical decline crosses into "mild cognitive impairment," then potentially into dementia.

This isn't caused by one factor. It's not just amyloid plaques, nor any single culprit as once thought. Cognitive aging is multifaceted—vascular health, inflammation, cellular stress, synaptic loss, reduced neuroplasticity, and yes, protein aggregation all play roles. It's like atherosclerosis, which we now know starts developing in early childhood, not suddenly in your 60s.

The key insight: the process is gradual, it starts early, and we've been calling it "normal" when it's really just common.

The Investment Theory: Why Starting Early Multiplies Returns

Here's where it gets interesting. The relationship between fluid and crystallized intelligence isn't just offset—it's generative.

The Investment Theory of Intelligence proposes that fluid intelligence actively shapes the development of crystallized intelligence over your lifetime. Here's the mechanism:

People with better fluid intelligence find learning easier to do
Because learning is easier, they find it more rewarding
Because it's rewarding and successful, they're more motivated to keep learning
Over years and decades, they accumulate more knowledge and wisdom

Better reasoning ability doesn't just make you better at abstract puzzles. It makes you better at learning everything, which means you build a richer, more organized knowledge base throughout life.

This is why enhancing fluid intelligence early—particularly in childhood—could have compounding benefits. A more efficient computational engine builds more sophisticated knowledge networks as learning occurs naturally.

Think of it like interest rates: starting with a slightly higher principal (better fluid intelligence) compounds dramatically over decades of learning.

The Holistic Strategy: Changing the Equation

Now imagine a different trajectory. Instead of:

Fluid intelligence: slow decline starting at 25
Crystallized intelligence: slow gains that eventually plateau

What if you could create:

Fluid intelligence: maintained or even enhanced
Crystallized intelligence: accelerated gains through better investment

This isn't science fiction. It's combining existing evidence into a coherent prevention and enhancement strategy:

Prevention: Slowing or Halting the Decline

Evidence suggests that certain interventions can protect against the typical fluid intelligence decline:

Microdose lithium has shown remarkable results in controlled trials—halting cognitive decline in mild cognitive impairment and Alzheimer's patients while placebo groups showed continued deterioration. Studies demonstrate maintained cognitive function over multi-year periods, with patients staying stable while untreated controls declined on memory and attention measures. The proposed mechanism involves neuroprotection, reduced tau phosphorylation, and enhanced amyloid clearance. (See our detailed article: Lithium for Cognitive Decline Prevention)

Lutein and zeaxanthin supplementation shows cognitive benefits across the lifespan, particularly for memory and processing speed, with evidence strongest in children and young adults for enhancement and in older adults for maintenance of neural function. (See our detailed article: Lutein, Zeaxanthin & Cognitive Function)

Enhancement: Actively Improving Capacity

But why stop at prevention? Evidence from cognitive training research—particularly programs like SMART (Strengthening Mental Abilities through Relational Training)—demonstrates that we can actively enhance fluid intelligence by training foundational cognitive processes.

SMART specifically trains relational reasoning, one of the most fundamental cognitive abilities underlying language, logic, mathematics, and complex thought. Multiple controlled trials have shown improvements in measured IQ, reading comprehension, and mathematical ability.

The key is training foundational processes (relational reasoning, working memory, processing speed, verbal fluency) rather than specific tasks. This produces genuine near transfer to the many real-world activities that rely on these core processes.

The Synergistic Effect

Here's where it gets exciting. If we prevent the typical decline in fluid intelligence (through lithium, lutein, lifestyle) and enhance fluid intelligence through training, we're not just maintaining the status quo.

According to investment theory, this enhanced fluid intelligence should accelerate the rate of crystallized intelligence gains over your lifetime. You're not just preserving what you had—you're changing the trajectory entirely.

Instead of the default equation:

Slowly losing fluid intelligence + slowly gaining crystallized intelligence = eventual net decline

You create a new equation:

Maintained/enhanced fluid intelligence + accelerated crystallized intelligence gains = sustained cognitive growth

What We Might Call "Supernormal"

If you maintain peak fluid intelligence while accumulating decades of knowledge and wisdom, your cognitive trajectory exceeds what we typically see with aging. You might call this "supernormal" cognition.

But really, it's just refusing to accept what we've mistaken for inevitable. The gradient is still there—you're just staying on the high end of it, or moving upward while others drift down.

This is most dramatic when started early (childhood, adolescence, young adulthood) due to compounding effects, but the trajectory can be changed at any age. The earlier you start, the more you benefit from compounding. But starting at 40, 50, or 60 still changes your trajectory meaningfully.

Different Stages, Same Principles

If you're young (under 25): You're in the investment phase. Enhancing your fluid intelligence now means decades of better learning, knowledge accumulation, and skill development. The compounding effects are maximal here.

If you're at peak (25-40): Prevention becomes relevant, but enhancement still offers significant benefits. You can maintain peak performance while adding to your crystallized intelligence at an accelerated rate. Think of it as locking in your cognitive prime and extending it indefinitely.

If you're middle-aged (40-60): You're likely experiencing subtle decline even if you haven't noticed. Active intervention can reverse this trend. Prevention becomes critical, and enhancement can still shift your trajectory meaningfully.

If you're older (60+): The evidence suggests it's not too late. Lithium trials in people with mild cognitive impairment showed participants maintaining cognitive function while controls declined. Training studies show older adults can enhance cognitive abilities. Your trajectory is changeable.

The Practical Path Forward

This isn't theoretical. The tools exist now:

Start with cognitive training. The complete SMART protocol is available free at Relatoria. It's evidence-based, scientifically validated, and trains the foundational cognitive process underlying complex thought. Even 15-20 minutes several times per week can produce measurable benefits.

Supplement with training in other foundational processes: working memory (Remember module), verbal fluency (Fluent module), and processing speed (Process module). These target the core overlapping cognitive processes that support thinking across domains.

Consider evidence-based supplementation. Read our detailed articles on lithium for cognitive prevention and lutein/zeaxanthin for cognitive support to understand the evidence, mechanisms, dosing, and practical considerations. These are well-studied interventions with substantial safety data.

Understand it's a long-term strategy. Just as the decline is gradual, the reversal and enhancement are gradual. You're changing a trajectory, not flipping a switch. Months and years of consistent practice reshape your cognitive path.

A New Relationship with Cognitive Aging

We've accepted cognitive decline as inevitable because it's common. But common isn't the same as necessary.

By understanding the mechanics—fluid and crystallized intelligence, investment theory, multifactorial causes, foundational processes—we can design interventions that change the equation.

The default trajectory is decline. But you can choose a different path: one where maintained reasoning ability accelerates knowledge accumulation, where prevention combines with enhancement, where your cognitive peak isn't a brief moment at 25 but a sustained and growing capacity across your lifespan.

The gradient is still there. But you get to choose which direction you move along it.

Ready to change your trajectory? Start with SMART training—completely free. Build the foundation that compounds over decades.