Schizophrenia is not classified as a neurodegenerative disease, but it does involve progressive brain changes that overlap with neurodegenerative conditions. The current scientific consensus treats schizophrenia primarily as a neurodevelopmental disorder, meaning its roots trace back to disruptions in brain development that begin long before symptoms appear. However, the reality is more complicated than either label suggests, and many researchers now argue that the strict split between “neurodevelopmental” and “neurodegenerative” is unhelpful.
Why Schizophrenia Is Called Neurodevelopmental
The dominant model of schizophrenia holds that pathological brain processes begin as early as the first and second trimesters of pregnancy. These early disruptions create neural circuits that are primed to generate psychotic symptoms later, typically during adolescence or young adulthood, when the brain undergoes a second wave of major reorganization and psychological stress tends to increase. This neurodevelopmental hypothesis has widespread support and forms the foundation of how major diagnostic systems like the DSM-5-TR categorize the disorder. In those systems, schizophrenia sits alongside other psychotic disorders, not alongside Alzheimer’s disease or Parkinson’s disease.
One key piece of evidence: people experiencing their very first psychotic episode already show measurably smaller gray matter volume compared to healthy controls. That means some brain differences are present before the illness has had any time to “degenerate” the brain, pointing to something that went differently during development rather than something that broke down afterward.
The Brain Does Lose Volume Faster
That said, the brain changes in schizophrenia don’t stop at diagnosis. Over the past 15 years, imaging studies have consistently found that people with schizophrenia lose brain tissue faster than healthy adults as they age. In one nine-year follow-up study, whole brain volume shrank by an average of 0.69% per year in people with schizophrenia, compared to 0.49% per year in healthy controls. That difference, roughly 40% faster, was statistically significant even after adjusting for factors like gender, alcohol use, and weight gain.
The extra shrinkage was not evenly distributed. The temporal lobe and the areas surrounding the brain’s fluid-filled ventricles were hit hardest. The temporal lobe plays a central role in language processing, memory, and auditory perception, all of which are commonly disrupted in schizophrenia. The frontal lobe also showed a trend toward greater loss, though it didn’t reach statistical significance in that particular study.
This pattern of ongoing, accelerated tissue loss looks, on brain scans, a lot like what happens in neurodegenerative diseases. But there’s an important distinction: in Alzheimer’s, the hallmark is a steadily progressive, gradual cognitive decline without extended plateaus. Schizophrenia follows a different trajectory.
How Cognitive Decline Unfolds
A large cohort study tracking 428 individuals with schizophrenia and other psychotic disorders mapped out three distinct phases of cognitive change. In the first phase, cognition was stable and normal. Then, about 14 years before the first psychotic episode, a gradual decline began at a rate of roughly 0.35 IQ points per year. This pre-illness decline was significantly faster in people who would develop schizophrenia than in those who would develop other psychotic disorders (0.15 IQ points per year).
After psychosis onset, the decline continued. At 22 years after onset, both groups were losing cognitive ability at 0.59 IQ points per year. Over the full observation period, people with schizophrenia lost an average of 16 IQ points. The researchers concluded that the trajectory was “consistent with both a neurodevelopmental and neurodegenerative pattern,” meaning the two frameworks aren’t mutually exclusive. The decline starts before symptoms appear (developmental), but it continues and accelerates afterward in a way that looks progressive (degenerative).
What’s Driving the Progressive Changes
Several biological processes may explain why the brain continues to change after schizophrenia develops. One major area of research involves the brain’s immune cells, called microglia. When these cells become overactive, they release inflammatory molecules and reactive oxygen species that damage neurons, disrupt the protective barrier between the brain and bloodstream, and reduce the brain’s ability to generate new cells. This cycle of oxidative stress and neuroinflammation can lead to white matter damage, neuron loss, and impaired signaling between brain regions.
Overactive microglia also stimulate another type of brain cell, astrocytes, to release excessive amounts of glutamate. Glutamate is the brain’s primary excitatory chemical messenger, and too much of it is toxic to neurons. This “excitotoxicity” is a mechanism shared with several recognized neurodegenerative diseases, which is part of why the question of whether schizophrenia is neurodegenerative keeps coming up.
The Role of Antipsychotic Medication
One complicating factor is that the medications used to treat schizophrenia may themselves affect brain volume, making it harder to separate disease-related changes from treatment-related ones. Longitudinal studies have found that cumulative exposure to antipsychotics is associated with reduced brain volume in certain regions, particularly the prefrontal cortex. Animal studies have confirmed that chronic exposure to both older and newer antipsychotics can reduce total gray matter volume.
However, the picture isn’t entirely negative. A placebo-controlled trial in people experiencing their first psychotic episode found that antipsychotic treatment increased volume in the pallidum, a deep brain structure involved in movement and reward, and that this increase was linked to greater symptom improvement. Studies of unmedicated patients still show brain volume reductions, confirming that the disease itself drives at least some of the loss. Newer antipsychotics may also exert a protective effect by promoting new cell growth and reducing oxidative stress, though this remains an active area of investigation.
Accelerated Aging as a Framework
A newer way of thinking about schizophrenia’s progressive features frames them as “accelerated aging” rather than neurodegeneration in the classical sense. Using a brain-imaging biomarker designed to measure the pace of whole-body aging, researchers across four separate datasets (totaling over 2,000 participants) found consistent evidence that adults with schizophrenia are aging biologically faster than their peers. The brain signature of this accelerated aging includes thinner cortex, smaller gray matter volume, altered signal patterns at the boundary between gray and white matter, and larger ventricles.
Notably, unaffected siblings of people with schizophrenia did not show this accelerated aging pattern, suggesting it’s tied to the illness itself rather than shared genetic background. This framing helps explain why schizophrenia shares some features with neurodegenerative diseases (progressive brain loss, cognitive decline) without fitting neatly into that category. The brain isn’t degenerating in the way Alzheimer’s destroys specific protein structures. Instead, it appears to be wearing down faster across the board.
Neuroprogression: A Middle Ground
Many researchers now prefer the term “neuroprogressive” to describe schizophrenia. This acknowledges that a developmental abnormality established early in life can manifest progressively, unfolding differently at different stages in both gray and white matter. The initial reduction in gray matter volume may stem from the original developmental disruption, while accelerated white matter loss accumulates with age and illness duration.
This framing matters for people living with schizophrenia because it suggests that the progressive component of the illness is not inevitable or fixed. If ongoing brain changes are driven partly by treatable processes like neuroinflammation, oxidative stress, or medication effects, then early and optimized treatment could potentially slow or limit those changes. The brain differences present at the first episode may be built in, but the trajectory that follows may be more modifiable than a true neurodegenerative disease would allow.